Offshore pipeline laying method capable of penetrating through existing embankment

Abstract

The invention discloses a method for laying an offshore pipeline penetrating through an existing dike. The method comprises the steps that S1, construction preparation is conducted; s2, engineering measurement is carried out; step S3, constructing a cofferdam; s4, engineering construction of the embankment penetrating pipe body is carried out; s5, embankment body filling is carried out; s6, soil is cemented, and earthwork is closed; s7, upstream face slope protection construction is conducted; s8, constructing an inner slope and a wave wall; step S9, construction of the embankment top pavement; s10, land pipe construction is carried out; and S11, cofferdam dismantling construction is conducted. The stability and safety of the dike structure are ensured, the investment cost is reduced, and the construction period is shortened.

Description

TECHNICAL FIELD

[0001] The present application belongs to a kind of offshore pipeline laying method crossing existing dike. BACKGROUND

[0002] At present, with the continuous development of oil and gas resources, more and more pipelines need to be laid in deep water area. In deep water environment, the change of water pressure and temperature puts higher requirements on the performance and stability of construction equipment, and the safety protection of construction personnel also faces greater challenges. When crossing existing dike for pipeline laying, the stability and safety of dike structure need to be ensured to avoid damage or failure of dike caused by construction activities.

[0003] Therefore, an offshore pipeline laying method crossing existing dike is provided. SUMMARY

[0004] To solve the above problems existing in the prior art, the present application provides an offshore pipeline laying method crossing existing dike, which ensures the stability and safety of dike structure, reduces investment cost and shortens construction period.

[0005] The technical scheme to achieve the above purpose is: An offshore pipeline laying method crossing existing dike, comprising: Step S1, construction preparation, including technical preparation, material preparation, construction site preparation, construction machinery and equipment allocation and construction force arrangement; Step S2, engineering measurement, including control point measurement, center line measurement, axis measurement, temporary level point measurement and measurement instrument detection; Step S3, cofferdam construction, including steel reinforced concrete retaining wall inner cofferdam construction, high-pressure rotary jet pile outer cofferdam construction and mud pipe bag outer cofferdam construction; Step S4, dike-crossing pipe main body engineering construction, including surface cleaning and measurement and setting-out, wave protection dike and road removal, dike body excavation, steel pipe welding and installation, pipe foundation treatment, concrete square package and backfill and dike repair; Step S5, dike body filling, including rolling embankment; Step S6, cement soil and closed air soil, including impermeable soil construction, geotextile laying, cement soil construction and closed air soil construction; Step S7, water-facing slope protection construction, using concrete four-corner hollow block stacking to protect and cover; Step S8, inner slope and wave protection wall construction, including wave protection wall and ground beam construction; Step S9, dike top pavement construction; Step S10, land pipe construction, including construction lofting measurement, trench excavation, pipe trench dewatering, excavation and pipe foundation, steel pipe transportation, steel pipe welding, steel pipe internal and external corrosion protection, steel pipe laying and installation, trench backfill and pipeline crossing treatment; Step S11, cofferdam demolition construction.

[0006] Preferably, in the step S1, the technical preparation includes: Organize relevant technical personnel and construction team, according to the embankment construction drawings, make good construction deployment, and according to the meteorological natural conditions of the project area, the construction site and the hydrogeological conditions, make good construction layout; Material preparation includes: According to the requirements of the quality assurance plan, the work plan of construction organization design, the construction machinery and equipment plan and the material supply plan, implement the main material source, optimize the supplier, and do well in ordering and purchasing; Construction site preparation includes: Check the basic situation of local material supply market, and reconnaissance the construction site, contact with the designated department of the first party, implement the construction water and electricity connection position, at the same time, according to the specific situation of construction site, lay out the construction water and electricity pipeline, set up office on site, build material and equipment warehouse, reasonably arrange personnel housing and living facilities; Construction machinery and equipment preparation includes: According to the construction machinery and equipment demand plan and construction requirements, organize construction machinery and equipment into the field.

[0007] Preferably, in the step S2, the control point surveying includes: Review the measurement of surveying and design department; According to the guide stake provided by the owner, add control network according to the construction needs; According to the site conditions, select the control points outside the construction operation range and in the higher position, so as to achieve good visibility of each control point; After the control points are selected, the control point coordinates in the whole engineering range are determined through the actual measurement and the adjustment calculation of the traverse closure; wherein, the control network is measured and set by 2 second level total station; The measurement of center line and axis includes: Take the center control stake provided by the surveying institute as the reference, measure and place the center line of the pipeline, and use the total station to place the accurate center position provided by the design drawing; The measurement of temporary benchmark includes: According to the national benchmark provided by the surveying and design department, set the temporary benchmark, and the distance of temporary benchmark setting is not more than 200m without adding conversion point; Wherein, the temporary benchmark is measured and closed with the design benchmark, and the temporary benchmark is set outside the construction range, and the temporary benchmark is reviewed at certain time intervals; The detection of measuring instrument includes: Before the project starts, all measuring instruments entering the site are inspected, and after being qualified, they are used within the effective period.

[0008] Preferably, in the step S3, the cofferdam of the reinforced concrete retaining wall is divided into two forms, one is high wall form, and the other is low wall form. The construction process of the cofferdam of the reinforced concrete retaining wall includes: measurement and line laying, earthwork excavation and ramming, cushion construction, foundation reinforcement manufacturing and installation, foundation formwork erection, foundation concrete pouring, wall formwork erection, wall concrete pouring, concrete curing, formwork removal and backfilling.

[0009] Preferably, in the step S3, the construction of the high-pressure rotary jet pile cofferdam includes: construction preparation, measurement and line laying, grouting process, cement dosage control, grouting treatment, consolidation body shape control and pile top strength assurance.

[0010] Preferably, in the step S3, in the construction of the filled pipe bag cofferdam, the main body of the cofferdam adopts the filled pipe bag earth cofferdam, and the high-pressure rotary jet pile is used as the impermeable body on the side close to the embankment.

[0011] Preferably, in the step S4, the table cleaning and measurement and line laying include: table cleaning, measurement and line laying, surface measurement control according to the following requirements, wave protection embankment and road removal, embankment excavation, steel pipe welding and installation, pipe foundation treatment, concrete block, concrete block reinforcement manufacturing and installation, concrete block formwork erection, concrete block concrete pouring, concrete block concrete curing, backfilling and embankment repair.

[0012] Preferably, in the step S5, the rolling filling includes: taking soil → unloading soil → paving soil → rolling → inspection.

[0013] Preferably, in the step S7, the buried protection is stacked by using concrete four-corner hollow blocks with a length of 28.51m, The four-corner hollow block concrete grade is C40; Before placing the four-foot hollow block facing, the block stone cushion slope should be checked; The placing sequence of the four-foot hollow block must follow the bottom-up and side-to-side advancing principle; The four-foot hollow block is placed regularly; In the step S8, the concrete wave protection wall and the ground beam are cast in place, one settlement joint is set every 10 meters, the adjacent joint is 20mm wide, the filling material in the joint is polyethylene foam board with a thickness of 20mm, the settlement joint should be set at the same cross-sectional position, the concrete is commercial concrete, the concrete strength grade of the concrete wave protection wall and the ground beam is C40; In the step S9, the embankment top pavement is constructed by mixing AC-25 type coarse-grained asphalt concrete and AC-13 type fine-grained asphalt concrete, the thickness of the coarse-grained asphalt concrete is 60mm, and the thickness of the fine-grained asphalt concrete is 40mm. The 7-day unconfined compressive strength of the cement stabilized macadam should be greater than 3.0 MPa; the compaction degree should be greater than 97%, and the crushed value of the macadam should be not greater than 35%; The C30 shoulder stone has a specification of 300mmx400mmxl000mm.

[0014] Preferably, in the step S10, construction lofting measurement is performed to re-measure the position and elevation of the pipeline to be connected before construction, and the existing pipeline and structures are measured before construction; Trench excavation: manual excavation and manual slope repair; Trench dewatering and excavation: when the base trench excavation approaches the design elevation of the base, 150-300 soil layers are reserved and removed before the next process; when the excavation depth of the foundation pit is less than 3m, it is recommended to use slope excavation or support, and the slope is determined according to the single buried depth and the surrounding soil conditions; Pipeline foundation: the pipeline foundation adopts a cement-soil foundation, the cement content is 16%, the 28-day compressive strength is not less than 0.8Mpa, and the compaction degree is not less than 0.95; Pipeline foundation construction process: base treatment → measurement and lofting → mixing → transportation and paving of soil → leveling → size and elevation adjustment → compaction → maintenance; Steel pipe transportation: after the pipe material is transported to the construction site, the joint acceptance is performed according to the procedure; Steel pipe welding: the steel pipe adopts hot-rolled steel strip as the pipe blank, and the spiral seam is welded by automatic submerged arc welding method; Steel pipe internal and external corrosion: the corrosion adopts non-toxic and solvent-free epoxy anticorrosive paint, and the steel pipe and pipe surface treatment adopt shot blasting; Steel pipe laying and installation: check the trench, pipe rack and pipe lowering; among them, the pipe lowering adopts mechanical pipe lowering; Trench backfilling: after the water pressure test is qualified, it should be backfilled in time, there should be no accumulated water in the trench during backfilling, the excavated sandy soil can be used for backfilling above the pipe top, but the scouring soil containing organic matter and shell impurities, or the soil containing gravel with a particle size greater than 15 cannot be used for backfilling; Pipeline crossing treatment: if the plastic pipe is on the top and the reinforced concrete pipe is on the bottom, the bottom of the upper pipe to the outer top of the lower pipe is >0.5m, no treatment is required; if the reinforced concrete pipe is on the top and the plastic pipe is on the bottom, the bottom of the upper pipe to the outer top of the lower pipe is ≤0.5m, the length of the sand filling in the range of the upper pipe trench is 1.5 times the outer diameter of the upper pipe on each side, and the lower plastic pipe is wrapped with concrete, and the length is 5m away from the upper pipe on each side; In the step S11, the inner cofferdam is a reinforced concrete cofferdam located on land, and the outer cofferdam is a filled mud pipe bag soil cofferdam located in the beach section, and there is no water operation risk, the inner cofferdam selects a crusher, and the outer cofferdam selects a backhoe excavator and a self-unloading truck to cooperate with earth excavation and removal.

[0015] Compared with the prior art, the beneficial effects of the present application are that the present application firstly constructs an inner cofferdam on the inner side of the dam and an outer cofferdam on the water-facing side of the dam, completes the cofferdam construction, then carries out the main body engineering construction of the pipe crossing the dam, then carries out the cement soil, closed gas earthwork, water-facing side, inner slope protection and wave protection wall and pavement construction, after the construction of the pipe crossing the dam is completed, the removal construction of the land pipe and the cofferdam is carried out, the stability and safety of the dam structure are ensured, the investment cost is reduced, and the construction period is shortened. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, illustrate the present application together with the embodiments thereof, and explain the present application, but do not constitute a limitation of the present application. In the drawings: Figure 1 is a flowchart of a method for laying a marine pipeline crossing an existing dam according to the present application; Figure 2 is a specific flowchart of the main body engineering construction of the pipe crossing the dam according to the present application; Figure 3 is a flowchart of the rolling filling process according to the present application. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0018] The present application mainly constructs an inner cofferdam (reinforced concrete retaining wall construction) on the inner side of the dam and an outer cofferdam (filling pipe belt and high-pressure jet grouting pile construction) on the water-facing side of the dam, completes the cofferdam construction, then carries out the main body engineering construction of the pipe crossing the dam (wave protection wall removal, dam body excavation, pipe foundation treatment, pipe section welding and pipeline outer concrete protection, dam body backfilling), then carries out the cement soil, closed gas earthwork, water-facing side, inner slope protection and wave protection wall and pavement construction. After the construction of the pipe crossing the dam is completed, the removal construction of the land pipe and the cofferdam is carried out, and the specific steps are as follows.

[0019] As shown in Figure 1 , a method for laying a marine pipeline crossing an existing dam, comprising: Step S1, construction preparation, including technical preparation, material preparation, construction site preparation, construction mechanical equipment allocation and construction force arrangement.

[0020] In the embodiments, the technical preparation includes: Organize relevant technical personnel and construction teams, according to the embankment construction drawings, make good construction deployment, and according to the meteorological conditions of the project area, construction site and hydrogeological conditions, make good construction plan layout; Material preparation includes: According to the requirements of the quality assurance plan, the work plan of the construction organization design, the construction machinery and equipment plan and the material supply plan, implement the main material source, optimize the supplier, and do well in ordering and purchasing; Construction site preparation includes: Check the basic situation of the local material supply market, and conduct a reconnaissance of the construction site, contact the designated departments of Party A, and implement the construction water and electricity connection position. At the same time, according to the specific situation of the construction site, lay out the construction water and electricity pipelines, set up the office on site, build material and equipment warehouses, and reasonably arrange personnel housing and living facilities; Construction machinery and equipment preparation includes: According to the construction machinery and equipment requirement plan and the construction requirements, organize the construction machinery and equipment into the site.

[0021] According to the characteristics of large project quantity, tight construction period and difficult construction, in order to strengthen management and improve engineering quality, and complete the construction task on schedule, our company is ready to dispatch a small number of experienced project managers, technical construction management personnel, and skilled embankment pipe construction technical personnel to participate in the construction of this project. And at each stage of the project, more construction organization design is planned to input sufficient labor force.

[0022] Step S2, engineering measurement, including control point measurement, center line measurement, axis measurement, temporary benchmark measurement and measurement instrument detection.

[0023] In the embodiment, the control point measurement includes: Review the measurement briefing of the surveying and designing department, and the review result is approved by the supervision and can be used. According to the guide stake provided by the owner, the control network is encrypted according to the construction needs. In order to ensure the credibility of the control network, the control points will be selected outside the construction operation range according to the site conditions. The visibility of each control point is good, which meets the construction needs. After the control points are selected, the coordinates of the control points in the entire engineering range are determined through actual measurement and closure adjustment calculation. The control network is measured and set by a 2-second level total station; The center line measurement and axis measurement include: The center control stake provided by the surveying and mapping institute is taken as the reference, the center line of the pipeline is measured and placed, and the well number provided by the design drawing is used to place the accurate center position by the total station; The temporary benchmark measurement includes: According to the national leveling points provided by the survey design department, the construction temporary leveling points are set, and the distance of the temporary leveling points is not greater than 200m without adding a conversion point for measuring height; Wherein, the temporary leveling points are closed with the design leveling points, and the temporary leveling points are set outside the construction range, and the temporary leveling points are rechecked at a certain time interval; The detection of the measuring instrument includes: Before the project starts, all measuring instruments entering the site are inspected, and after being qualified, they are used within the effective period.

[0024] Step S3, cofferdam construction, including reinforced concrete retaining wall inner cofferdam construction, high-pressure rotary jet pile outer cofferdam construction and filled mud pipe bag outer cofferdam construction.

[0025] In this embankment pipe construction operation, in order to ensure the stability and safety of the embankment inside and the embankment itself in the stage of passing through and breaking the embankment, and to provide a prerequisite for the subsequent dry land construction and the connection of the pipe section, a reinforced concrete retaining wall inner cofferdam is first poured on the inside of the embankment before the embankment is broken, and the existing seawall bottom riprap stabilization layer is used. The outer cofferdam foundation uses φ700 high-pressure rotary jet pile as the bottom water isolation, and the upper part uses filled mud pipe bag as the embankment outside soil cofferdam. After the construction of the inner and outer cofferdams is completed, one water pump is arranged at each of the inner and outer cofferdams, which can take water pumping measures in the first time when rainwater or seawater seeps into the cofferdam to cause water accumulation, to ensure dry land construction in the cofferdam and ensure the construction progress according to the schedule.

[0026] In the embodiment, the reinforced concrete retaining wall inner cofferdam is divided into two forms in total, one is a high wall form: the total height from the bottom of the bottom plate to the top of the wall is 3470mm, and the total width of the bottom plate is 3500mm; the second is a low wall form: the total height from the bottom of the bottom plate to the top of the wall is 1470mm, and the total width of the bottom plate is 2500mm; the reinforced concrete retaining wall inner cofferdam is poured with C30 concrete, and the internal reinforcement of the inner cofferdam retaining wall is made of HRB400φ10, 12, 14 steel bars; The reinforced concrete retaining wall inner cofferdam construction process includes: Measurement and setting out: According to the construction drawing and coordinate point, the center line of the reinforced concrete retaining wall, the position of the foundation plane and the longitudinal elevation line are measured and set out, the plane and elevation control points are well marked, and the marks are well marked; Earthwork excavation and ramming: When excavating earthwork not at the same elevation, it should be done in the order of deep to shallow; The excavation process should be slow to avoid over-excavation and disturbance of the bottom layer; After the excavation is completed, the original soil is promptly rammed and leveled to the design elevation; Paving construction: After the owner and the supervision unit check the groove and find it qualified, the cushion construction is carried out according to the design drawings; After the completion of the cushion construction, the design elevation is reviewed in time and the wall axis, foundation size line and steel control line are determined according to the design drawings and the middle line stake of the reinforced concrete retaining wall; Foundation steel production and installation: The steel is rechecked according to the relevant provisions and used after being qualified; Before the steel is bound, the cushion mud and water are cleaned, and the main force reinforcement is placed first and then the distribution reinforcement is placed according to the determined spacing; When the steel is bound, the order or eight-character buckle is used, and the intersection of the steel mesh should be bound outside; The cushion block is placed between the steel and the formwork; When the double-layer steel mesh of the foundation is bound, the support foot with sufficient strength is set; Foundation formwork erection: The foundation formwork is used to bear the impact force and lateral pressure of the poured concrete. When the formwork is supported, the lower opening of the formwork is first horizontally supported, and then the inclined support is fixed. The formwork should have sufficient strength, rigidity and stability to bear the impact force and lateral pressure of the poured concrete. The design shape, size and position of the reinforced concrete retaining wall should be accurate and convenient to disassemble. The formwork joint should be tight and not leaky or misaligned. After the axis and formwork line are laid, the pre-inspection procedures should be handled; Pouring of foundation concrete: The free fall of the concrete pouring should not be more than 2m. When it is more than 2m, the guide pipe or chute is used for transportation; The concrete should be poured in layers, and the thickness of each layer should not exceed 300mm. The pouring and tamping of the next layer of concrete should be completed before the previous layer of concrete is initially set. When the next layer of concrete is vibrated, the vibrating rod should be inserted into the previous layer 50mm-100mm; Wall steel production and installation: consistent with the requirements of foundation steel production and installation; Erection of wall formwork: The wall formwork is installed according to the position line. The formwork should be firmly supported to prevent the formwork from loosening and running during the pouring of concrete. The formwork on the outside is assembled according to the design scheme and positioned according to the position line, and then the pull rod is installed; After the formwork is installed, the supervisor checks whether the buckles and bolts are firm, whether the formwork joints and lower openings are tight, and handles the pre-inspection procedures; Pouring of wall concrete: Before pouring the wall concrete, a 15mm-20mm thick mortar bonding layer with the same strength grade as the wall concrete is uniformly poured at the bottom joint; The concrete shall be poured in layers according to the relevant provisions of the standard, and shall be vibrated and compacted. The thickness of each layer shall not exceed 300 mm. The concrete pouring points shall be arranged dispersedly. The wall shall be continuously poured. The interval between two layers shall not exceed the initial setting time of the concrete. The construction joint of the wall shall be arranged at the designed expansion joint. After the concrete is vibrated and compacted, the exposed reinforcing steel bars at the top shall be arranged. The top of the wall shall be leveled according to the design elevation control line by using a wooden trowel. Concrete curing: After the concrete is poured, it shall be covered and watered within 12 hours. The watering shall be performed so as to keep the concrete in a sufficiently wet state. The curing period shall not be less than 7 days. The curing period may be appropriately prolonged according to the air humidity, temperature, cement variety and additional agent. Form removal: When the strength of the concrete reaches 75% of the total strength, the side form shall be removed. First, the tie rods shall be loosened and removed in sections. The forms shall be removed in blocks. After the forms and supports are removed, they shall be repaired and arranged. The forms and supports shall be properly stored. Backfilling: After the forms are removed and the concrete is cured, the backfilling shall be performed according to the design requirements. The original soil shall be used for backfilling in the high wall type inner cofferdam. The stone residue shall be used for backfilling in the low wall type inner cofferdam.

[0027] In the construction of the high-pressure jet grouting pile outer cofferdam in the example, the diameter of the high-pressure jet grouting pile of the water stop curtain is 700 mm, and the overlap is 200 mm. The ground reinforcement is φ700@500, and the double pipe method is used for construction at two places. The ordinary portland cement with a strength grade of 42.5 is used for the high-pressure jet grouting pile outer cofferdam. The cement content is 25%, the water-cement ratio is 0.8-1.2, and the grouting pressure is not less than 20 MPa. Before the construction, the test pile shall be performed. The grouting pressure and the water-cement ratio may be adjusted according to the test pile results. The distance between the jet hole and the high-pressure grouting pump shall not be greater than 50 m. The deviation of the position of the drilling hole from the designed position shall not be greater than 50 mm. During the construction, the verticality of the pile shall be controlled within 1 / 250. The deviation of the pile position shall not exceed 50 mm. The deviation of the top and bottom elevations of the pile shall not be greater than 100 mm. The high-pressure jet grouting pile shall ensure the overlap quality. During the construction, the pile shall be engaged, and the upper and lower parts shall be uniform and not leak water.

[0028] After the high-pressure jet grouting is completed, the jet pipe shall be quickly pulled out. In order to prevent the solidification shrinkage of the slurry from affecting the elevation of the pile top, the original hole position slurry pouring and backfilling or twice grouting and other measures may be used as necessary. During the construction of high-pressure jet grouting pile, the surrounding buildings, underground pipelines and road surface should be observed. If the heave or settlement occurs, the construction technology should be adjusted in time, and the measures such as skip punching should be taken to reduce the influence of high-pressure jet grouting pile construction on the surrounding environment. The construction of high-pressure jet grouting pile includes: Construction preparation: According to the surrounding situation of the dam, arrange excavator to carry out site leveling within the construction range of high-pressure jet grouting pile, and excavate and replace the soil layer within the construction range of high-pressure jet grouting pile; Select the appropriate place of the dam for test pile to determine the corresponding technical parameters: actual geological conditions, nozzle model and specification, footage and lifting speed, grouting pressure, grouting flow, water-cement ratio and cement content, pile diameter and pile strength; Do a good job of water and electricity and hardening road work before the construction of jet grouting pile at the dam; Before the construction of high-pressure jet grouting pile, the operator should check the operation of the machine and prepare the spare parts; Label and number the high-pressure jet grouting pile according to the construction sequence and record it in a book; Layout measurement: According to the control points provided by the construction unit, use the traverse control method to layout the main axis of the high-pressure jet grouting pile construction position; According to the actual construction site situation, lead the main axis control point to a position not affected and disturbed, and protect it; Draw measurement review and certification and high-pressure jet grouting pile hole position layout map in time Grouting process: High-pressure jet grouting is carried out from bottom to top and continuously. If a stoppage fault occurs during construction, after repair, it needs to be connected downward by not less than 500mm in length to ensure the integrity of the consolidated body. Due to the complex geological conditions of the dam foundation, the depth changes greatly along the depth, there are many soil layers, and the density, water content, soil particle composition and underground water state are very different and different. If a single technical parameter is used for jet grouting, it will form a consolidated body with extremely uneven diameter, resulting in inconsistent jet grouting diameter and affecting the bearing capacity. Therefore, according to the characteristics of the dam foundation soil layer, relative measures should be taken to complete grouting, especially for hard soil and clay stone parts: the lifting speed and rotation speed of deep soil layer should be appropriately slowed down or the jet grouting pressure should be increased; If a stoppage fault occurs during construction, after repair, it needs to be connected downward by not less than 500mm in length; According to the characteristics of the dam foundation soil layer, relative measures should be taken to complete grouting, especially for hard soil and clay stone parts: the lifting speed and rotation speed of deep soil layer should be appropriately slowed down or the jet grouting pressure should be increased; Under the condition of not changing the jet grouting technical parameters, repeat grouting for the same soil layer; Control of cement usage: Controlling the amount of cement used is crucial during the shotcrete lifting process. The amount of cement used is directly related to the shotcrete pressure, nozzle diameter, lifting speed, and water-cement ratio. Specific control methods include: If there is excess cement, increase the spraying pressure, increase the nozzle diameter, and slow down the lifting speed. If the amount of cement is insufficient, reduce the pressure appropriately while ensuring the pile diameter, reduce the nozzle diameter appropriately, increase the lifting speed appropriately while ensuring the pile strength, and increase the water-cement ratio. In light of the specific circumstances of this project, each pile is mixed in stages, and the construction water is precisely measured to ensure a fixed water-to-cement ratio for mixing the cement slurry. By adjusting the above parameters, the amount of cement can be guaranteed to meet the design requirements. In response to the cement slurry settling phenomenon (due to the high density of the cement slurry), a re-mixing is carried out from the top of the pile downwards for 3.0m to ensure the strength of the cement-soil mixture above the pile. Treatment of overflowing slurry: During the jet grouting process, it is important to assess the approximate effect of the jet grouting and determine the rationality of the parameters. If the amount of grout overflow is less than 20% of the amount of grout injected, it is considered normal. If it exceeds 20% or there is no grout injection at all, the cause should be investigated and appropriate measures should be taken in a timely manner. When the flow rate remains constant but the pressure suddenly drops, the leakage at the location should be checked. If necessary, the grouting pipe should be pulled out to check its sealing performance. If there is no grout or intermittent grouting, or if the soil is loose, it is considered a normal phenomenon and re-grouting should be carried out as appropriate. If there are cavities or tunnels nearby, the grouting pipe should not be raised, and grouting should continue until grouting occurs, or the grouting pipe should be pulled out and the grout should be allowed to solidify before grouting is resumed until grouting occurs. If necessary, quick-setting grout should be used to facilitate solidification of the grout near the grouting pipe. Measures to reduce grout leakage include: increasing the jet grouting pressure while keeping the grout volume constant; appropriately reducing the nozzle diameter while keeping the jet grouting pressure constant; and increasing the lifting and rotation speed. Solidified body shape control: During construction, grouting is carried out by lifting and rotating simultaneously. Considering the formation of deep parts, when spraying at the bottom, the spraying pressure is increased, repeated spraying is performed, or the rotation and lifting speed of the nozzle is reduced. For different soil layers, the pressure is appropriately increased and the rotation and lifting speed of the nozzle is reduced to make the aggregate uniform. Ensure pile top strength: When the cement slurry is used for jetting, there is shrinkage in the setting process of the mixed slurry and soil particles due to water separation of the slurry, resulting in a concave hole at the top of the solidified body, and the depth of the concave hole varies with the properties of the stratum, water separation of the slurry, diameter of the solidified body, and depth of the pore formation; the depth of the concave hole of the double-tube rotary jetting is generally 1-1.5 times of the designed pile diameter. This concave hole phenomenon is extremely unfavorable for ground reinforcement, and effective measures must be taken to eliminate it. In order to prevent the concave hole phenomenon caused by shrinkage of the slurry during setting and to facilitate the ground reinforcement to achieve an ideal effect, super-high rotary jetting and backfilling of the slurry are adopted to ensure the strength of the pile top. Measures to prevent stringing holes: In the construction process, each unit adopts the construction method of jumping and hitting; In the high compression soil layer, the jetting pressure is appropriately reduced; The lifting speed and the rotation speed are accelerated.

[0029] In the construction of the outer cofferdam of the filled mud pipe bag in the embodiment, the main body of the outer cofferdam is a filled mud pipe bag earth cofferdam, and a high-pressure rotary jetting pile is used as a seepage prevention body on the side close to the embankment; wherein, during the construction of the earth cofferdam, a block stone pressing foot is arranged at the bottom of the inner side of the cofferdam, a 630g / m2 geotextile impermeable layer is arranged at the outer side, a 300mm thick gravel cushion is arranged on the geotextile, and a 500mm thick dry masonry block stone is arranged as a slope protection and water retaining structure; and the bottom of the outer side is a riprap prism, which is used as a stable embankment body. The height of the filled mud pipe bag earth cofferdam embankment is 3500mm, the bottom width of the embankment body is 18.625m, and the top width is 4m; wherein, the block stone pressing foot on the water-facing side of the cofferdam has a bottom width of 1m and a height of 1m; the riprap prism at the bottom of the water-backing side of the cofferdam has a bottom width of 1.458m and a height of 1m; and the top part adopts: geotextile→gravel cushion→dry masonry block stone. The weight of the block stone pressing foot and the riprap prism is ≥150kg, the stone material bulk density is not less than 24KN / m 3 , the size of the block stone riprap is uniform, the rock softening coefficient is ≥0.80, and the compressive strength is ≥40mpa; Riprap bottom protection: the thickness of the riprap is uniform, the surface of the riprap is rationally laid, and the block stones fit closely. The construction of the filled mud pipe bag outer cofferdam includes: The width of the filled mud pipe bag is determined according to the designed section, and multiple filling sleeves are arranged on each pipe bag according to the size, and they are arranged in a square shape. The splicing joint of the pipe bag is perpendicular to the axis direction of the cofferdam, and one joint parallel to the embankment axis direction is arranged at one end of the bag body, the splicing strength meets the design requirements, the pipe bag is processed, folded into shape according to the design requirements, and the size is marked. Before the large-scale filling construction, the test filling is carried out at the side of the dam to obtain the parameters (such as the slurry depth, the bag size, the slurry pressure, the solidification time, the solidification speed and the deposition rate) to guide the large-area filling operation. The filling pipe bag construction is the key process of the cofferdam project, which is an important process to ensure the engineering quality, speed up the engineering progress and ensure the construction period. The bag body is laid and fixed by artificial, and the pipe opening is connected, and the slurry pump is started to begin filling. During the filling process, the flow, flow direction and flow rate of the slurry are observed, and the direction of the delivery pipe opening is adjusted in time to prevent the uneven stress of the bag body from causing deformation and displacement. When the bag body is gradually filled, attention should be paid to the limitation of the grouting pressure to prevent the bag from being broken. The thickness of each layer of bag body is limited to 0.5-0.7m. If the secondary filling construction is adopted when the bag body is not filled to the ideal thickness at one time, special attention should be paid to keeping the thickness of the bag body in the same layer consistent to facilitate the construction and quality control of the next layer. The measurement work during the filling process is strengthened, and the edge line is measured during the filling of each layer according to the drawings and the construction conditions. The filling bag body is laid in layers during the construction, and is parallel or perpendicular to the dam axis, and is neatly stacked, and the upper and lower layers are staggered, and the gap and through slit between the bag bodies are not allowed. The control during the filling process is strengthened, and the bag body is uniformly increased from the beginning of the filling to the end of the filtration to make the pipe bag flat. After the filtration is completed, the sand is manually filled and leveled at the pipe opening. The bag body should not be filled with another bag body on the upper part before the filtration is completed. Before the completion of the construction of each layer of the filling pipe bag and the completion of the filtration, the block stone pressure foot on the inside of the cofferdam and the geotextile, gravel cushion and rock prism construction on the outside of the cofferdam are simultaneously started by the construction workers within 2m of the cofferdam construction height. Above 2m of the cofferdam construction height, the geotextile, gravel cushion and dry block stone construction on the outside of the cofferdam are carried out. Filling pipe bag construction procedure: The bag body is laid in layers and should be neatly stacked, and the upper and lower layers are staggered, and the gap between the bag bodies should not be less than 2m, and the through slit and through hole between the bag bodies should not be left. When the newly filled bag body is placed on the prism on the outside of the cofferdam and the block stone pressure foot on the inside, protective measures should be taken as required, and the bag cloth should not be cut by sharp block stones. If the bag body is damaged or has holes, it should be repaired in time, and the original bag body material should be used for repair, and the seam width should not be less than 150cm. The joints between adjacent sand bags should be tightly closed. When the bag body is filled on the upper part of another bag body, the joint should be filled first to make the bag body tightly close to the outer surface of the lower layer of bag body under the action of mud gravity to prevent the bag from being suspended at the joint to form a triangular joint. The through-length bottom triangular joint should not be allowed, and the local triangular joint should be filled with bagged sand tightly. The filling pressure of the slurry pump should not be too large, and the outlet pressure of the pipeline should be limited to 0.2-0.3MPa; The filling of the pipe bag must be evenly loaded according to the design, and during the construction process, the upper pipe bag must be laid after the lower pipe bag is drained and consolidated; During the construction period, the settlement displacement observation should be enhanced, and if abnormal phenomena occur, the loading should be stopped immediately, and then measures should be taken according to the specific situation; Before the slope is leveled or the geotextile is laid, the sand or bagged sand should be leveled and compacted, and the original pipe bag body should not be damaged. If the bag must be cut and the slope must be cut, the bag should be sewn and packed again; The geotextile is used to fill the gap between the bags to prevent the gap between the bags from forming a gap under the penetration of water flow, ensuring that the cofferdam can play its designed role. 630g / m2 geotextile is used as the filling material; Due to the design requirements of the filling pipe bag construction of the peripheral cofferdam, in order to ensure the quality of the cofferdam construction, the project department slows down the filling speed of the cofferdam and resettlement according to the requirements, to ensure that the cofferdam is completed according to the design requirements and quality and quantity.

[0030] Step S4, main body construction of the pipe through the embankment, including clearing and measuring and setting out, removing the wave embankment and road, excavating the embankment, welding and installing the steel pipe, treating the pipe foundation, concrete square package and backfilling and repairing the dam.

[0031] As shown in Figure 2 , clearing and measuring and setting out includes: Clearing: The roots and grasses in the pipe excavation area are completely removed by manual and excavator methods; Measuring and setting out: After clearing, the measuring and setting out of the excavation surface and axis is carried out to determine the excavation position and range; The measuring and setting out work is responsible by the full-time surveyor, and the strict measurement record and checking and archiving system is adopted, the instrument has been checked, the design drawings and pile record are checked, the temporary level point is established, the protection work is done, and the closure retest is carried out to eliminate the cumulative error; All control points should be retested before construction, and the retest accuracy must meet the relevant specification requirements, and the protection and periodic retest should be properly protected during the construction process; If the original traverse point cannot meet the construction requirements, it should be encrypted to ensure that the adjacent traverse points can be seen during the whole construction process; The starting and ending points of the traverse should be compared with the design unit measurement results, and the measurement accuracy should meet the design requirements, and the coordinate relative closure error is 1 / 10000; Before using the set level, carefully check and close with the national level, beyond the allowed error range, should be identified and reported immediately, if found individual traverse point affected by construction, will be moved out of the impact; The measurement of the line is marked with lime powder. Before the excavation, the technical disclosure is made to the workers, and the construction is carried out according to the drawing; The surface measurement control is controlled according to the following requirements: The interval of the measurement section is determined according to the design or the requirements of the supervision engineer. The section is measured when the change is large outside the section. The height is introduced to the section pile, and the transit and level are used to measure the section by the sight method. The area calculation method is used to calculate the earthwork volume after the measurement is completed. The calculation is combined with the graphic method and the analytical method; Wave protection and road removal: After completing the table and measurement control, the excavator is organized to enter the construction area and manually cooperate to remove the wave protection and road in the construction area. The waste removed by construction is timely transported to the corresponding area not affecting the pipeline construction for temporary stacking. The waste stacking height is not greater than 1.5m; Dyke body excavation: The dyke body foundation trench excavation is carried out by manual cooperation with the excavator; Specifically includes: Construction preparation: Review the construction organization design and verify the adjustment of earthwork transportation; Set up drainage facilities: before excavation, make good water interception ditch and build temporary drainage facilities; According to the construction needs, all kinds of necessary construction machinery are matched; When excavating, the slope gradient should be reviewed at any time to ensure the excavation slope. When excavating to the bottom of the trench, the bottom elevation should be reviewed at any time to avoid overexcavation. The unqualified materials such as stones and hard objects at the bottom of the trench must be removed, and the holes formed thereby are leveled to the accurate elevation with sand and gravel; General requirements for dyke body excavation: The dyke body earthwork open excavation should be carried out from top to bottom in layers and sections in turn. During construction, a certain slope is formed at any time to facilitate drainage. Water accumulation should be avoided in the stable range of the slope. Drainage ditches are excavated at the edge of the trench to ensure smooth drainage; During the excavation process, the level is used for tracking observation to prevent overexcavation. After the basic formation of the groove, a protection layer of not less than 20cm is reserved for manual excavation, and the original soil is protected from disturbance. The original soil disturbed is compacted. If local overexcavation occurs due to special circumstances, it is treated by backfilling according to the relevant requirements to ensure the compactness; The trench excavation is sloped according to the requirements of the construction drawing to ensure the stability of the slope; When construction is carried out in rainy days, the slope surface shall be covered with plastic cloth to prevent gully erosion. The top of the trench shall be first repaired with a water cutting ridge to prevent rainwater from flowing into the trench and eroding the slope; After the trench is excavated and shaped to meet the design requirements and is passed by the relevant party, the follow-up work shall be promptly carried out to strive to complete the foundation cushion construction in the shortest time. After the structural concrete strength reaches the allowable strength required by the design, the earthwork backfill shall be carried out in time; In case of strong wind weather, the slope surface shall be watered or covered with plastic cloth to maintain a good construction environment on site; The classification of excavated soil quality shall be paid attention to to ensure the quality of backfill soil; The excavated slag and discarded slag shall be classified and stacked at the designated site by the supervisor. After the completion of the project, the site shall be restored and protected according to the construction requirements; The operation points of excavated earthwork are as follows: the organic soil in the lower layer of the trench and the soil which is difficult to dry and compact shall be removed and replaced. The soil with CBR value less than the relevant provisions or unsuitable for backfill shall be removed and replaced. The stratified longitudinal excavation method shall be adopted and two excavators shall be provided for earthwork excavation; When the embankment trench is excavated, the construction shall be carried out from the inside to the outside and from the outside to the inside. The excavator shall be used to excavate the soil in the trench. The trench width shall be excavated according to the design requirements. The excavated loose soil shall be removed in time; The blocking body and night warning light and lighting shall be set at the top edge of the excavated trench according to the requirements; During the construction process, special personnel shall be arranged to patrol and inspect the embankment trench to ensure the stability of the trench slope. If any abnormal reaction occurs, the personnel shall promptly report to the project department and take measures in the first time; The embankment trench excavation shall be carried out in layers and sections in turn. The drainage system shall be kept unobstructed during the construction process; The construction points of the embankment trench in the rainy season are as follows: ① The selected rainy season construction site shall be investigated and studied in detail. The implementable rainy season construction organization plan shall be prepared; ② The construction access road shall be repaired and ensured to be unobstructed in rainy days; ③ The temporary drainage facilities shall be constructed to ensure that the construction site is not flooded and the ground water can be drained in time; ④ Adequate engineering materials and living materials shall be stored; Welding and installation of steel pipe: The steel pipe shall be DN1800 steel pipe. Each section of steel pipe shall be 12m long. The welding shall be double-sided welding; Pipe foundation treatment: After the embankment trench excavation is completed and is passed by the supervision engineer, the pipe foundation treatment of the embankment trench bottom shall be immediately organized. The pipe foundation is C30 plain concrete 300mm behind. The plain concrete foundation is set in a trapezoidal shape with a slope of 1:3. The collected and distributed gravel backfill for the trench slope shall be used. The pipe foundation plain concrete pouring shall be pumped and delivered with manual leveling; Concrete package: After the completion of the assembly welding and splicing installation of the dike-penetrating pipe, the organization of the dike-penetrating pipe's reinforced concrete package is started; Before the package construction, the steel pipe is roughened, that is, geotextile is wound on the smooth surface of the steel pipe, and the geotextile is made of 145g split film silk woven cloth for construction; The package concrete adopts C40 concrete, and the steel bar adopts HRB400, and the outer layer of the steel bar has a protective layer with a thickness of 100mm, and a φ8@150 double-layer double-direction mesh bar is arranged in the protective layer; Before the steel bar is bound, the cushion layer mud and water should be cleaned, and the cushion block should be placed between the steel bar and the formwork, the thickness of the protective layer should meet the design requirements, the main force steel bar is placed first, and then the distribution steel bar is placed according to the fixed interval, the steel bar is bound, the intersection points of the steel mesh bar should be bound outside, and when the double-layer steel mesh is bound, the support with sufficient strength should be arranged; The dike-penetrating pipe's reinforced concrete package is made of C40 concrete, and the steel bar adopts HRB400, and the outer layer of the steel bar has a protective layer with a thickness of 100mm, and a φ8@150 double-layer double-direction mesh bar is arranged in the protective layer; Pouring the package concrete: Before pouring the package concrete, a 15mm-20mm thick mortar bonding layer with the same strength grade as the package concrete is uniformly poured at the joint between the bottom and the cushion layer; the concrete should be poured in layers according to the specification, and the concrete should be vibrated and compacted, the thickness of each layer should not be greater than 300mm, the concrete should be poured continuously, and the interval between each layer should not be greater than the initial setting time of the concrete; after the concrete is poured and vibrated, the exposed steel bar at the top is arranged, and the top surface is repaired and leveled; Concrete curing: After the concrete is poured, it should be covered and watered within 12h, the watering frequency should be sufficient to keep the concrete wet, and the curing period should be at least 7d, and the period should be appropriately extended according to the air humidity, temperature, cement variety and the use of external additives; Backfilling and repairing the dam: After the completion of the dike-penetrating pipe main project construction and meeting the requirements, the project department organizes the dam filling operation.

[0032] Step S5, dam filling, including rolling compaction.

[0033] As shown in Figure 3 , the rolling compaction includes taking soil → unloading soil → paving soil → rolling → inspection; The filling operation should meet the following requirements: The soil quality and its water content of the lifted soil should meet the requirements determined by the design and rolling test; The filling shall be done from the lower part to the upper part by horizontal layers, and shall not be done by filling along the slope. For the quality of the pavement at the joint of the new and old embankment, the old embankment shall be excavated into steps, and then the filling and rolling shall be done by layers; Since the length of the broken embankment is short, the whole section is rolled and backfilled as a whole; The working surface shall be uniformly filled and rolled by layers, and personnel or earth leveling equipment shall be provided to participate in the leveling operation, and the boundary ditch shall be strictly prohibited; When the surface of the filled soil and graded gravel is dried before compaction, it shall be moistened with water; When the surface of the filled soil and graded gravel is dried before compaction, it shall be moistened with water; If local "spring soil", layer surface, layer cavity, loose soil layer or shear failure are found, they shall be treated in time, and the new soil shall be filled after passing the inspection; During the construction process, the installation of observation equipment and the normal operation of measurement work shall be ensured, and the observation equipment and measurement marks shall be protected; During the rolling process, the construction speed shall be strictly controlled, and if necessary, settlement and displacement observation points shall be set on the foundation and slope surface, and the safety construction shall be guided according to the analysis results of the observation data. Generally speaking, the construction is safe and reliable when the horizontal displacement is less than 5mm / d and the vertical settlement is less than 10mm / d; For the temporary slope of the upper embankment occupying the section of the embankment body, the missing part shall be treated, and the old soil shall be loosened, and the new filled soil shall be uniformly filled and compacted by layers according to the filling requirements, so as to ensure that the quality of the missing part is the same as that of the embankment body; After the filling of the embankment body is completed, the slope shall be rolled and compacted, and the pits and depressions on the embankment protection ground on both sides shall be filled and leveled; The following requirements shall be met during the filling operation: The soil shall be filled to the specified position according to the design requirements, and the sand (gravel) or other water permeable materials shall not be mixed with the cohesive soil and graded gravel, and the impurities in the upper embankment soil shall be removed; The soil shall be unloaded by the advancing method or the retreating method, and the graded gravel shall be unloaded by the retreating method, and if the particle separation phenomenon occurs, it shall be uniformly mixed again; The thickness of the auxiliary material and the limited size of the soil block shall be determined by the rolling test; When the soil is filled to the embankment edge, a certain amount of excess shall be filled outside the design edge line: the manual filling shall be 10cm, and the mechanical filling shall be 30cm; The following requirements shall be met during the compaction operation: Before construction, rolling test should be done to verify whether the rolling quality can reach the design dry density value. Field adhesion test is a very important part of embankment construction by rolling. Scientific and reasonable parameters can only be obtained through test; Segmented filling, each segment should be marked to prevent under-pressing, under-pressing and over-pressing. Over-pressing is not only harmful to the quality of the body, but also destructive to the structure of the body. The position of the upper and lower layer segment joint should be staggered; The rolling construction should meet the following requirements: ①The rolling mechanical walking direction should be parallel to the embankment axis, which can effectively improve the continuity and integrity of the body, and is beneficial to improve the anti-seepage function of the body. The construction machinery should not be perpendicular to the embankment axis direction, because it is not only extremely inconvenient to operate, but also increases the number of joint of operation section, which leaves too many weak parts in the embankment, which is not conducive to the overall function of the project; ②Segmented rolling, the overlapping pressing width of adjacent working surfaces should not be less than 0.6m parallel to the axis direction; and should not be less than 3.0m in the straight embankment axis direction; ③The speed of mechanical rolling should be controlled to not more than the following provisions: 2km / h for flat rolling, 2km / h for vibrating roller, and 2km / h for shovel loader; ④The parts not rolled by machinery should be supplemented by rammer compaction, and the ramming should adopt the method of continuous chain, with double-directional overlapping pressure, 1 / 3 of ramming and 1 / 3 of rolling. When segmental ramming, the ramming trace overlapping width should not be less than 1 / 3 of the ramming diameter; The rolling embankment construction in rainy days and low temperature should meet the following requirements: The working surface should be compacted in time before rain, and made into a central convex to the two sides. When it rains, the clay filling should be stopped, and the clay filling surface should not be trampled by people. And vehicles should be strictly prohibited. After the rain, the construction should be resumed, the filling surface should be treated by airing and re-pressing, and the surface layer should be cleaned again if necessary, and the construction should be resumed in time after the quality inspection is qualified; The embankment should not be constructed in negative temperature: if there are heat preservation measures, it is allowed to be constructed in the case that the temperature is not lower than-10℃; The soil material should be taken in positive temperature when it is constructed in negative temperature; The procedures such as soil loading, auxiliary soil, rolling and sampling should be operated quickly and continuously; The air temperature should be above-1℃ when the soil is compacted; The water content of clay should not be more than 90% of the plastic limit when it is constructed in negative temperature; The thickness of the soil should be appropriately reduced than the conventional requirement, or heavy machinery rolling should be adopted; No ice and snow should be mixed in the filling soil; The rolling embankment should be compacted every layer, and the compaction degree should be inspected by third party, and the next stage construction can be started after meeting the requirements.

[0034] Step S6, cement soil, closed gas soil, including anti-seepage soil construction, geotextile laying, cement soil construction and closed gas soil construction.

[0035] In the embodiment, the anti-seepage soil construction: The earthwork filling is constructed according to the principle of stone leading and earthwork following. Before the construction of the impervious earth, the small stones and slag on the surface are cleaned. The impervious earth is taken from the sea by the piston sludge pump. The earth is taken 300 m away from the dike foot. The thickness of the taken earth is not more than 2 m. The filling thickness of each layer is controlled to be not more than 1 m, so as to facilitate the drainage and air drying. The interval period of each layer is not less than 20 days. The geotextile is laid: The 630 g / m2 geotextile is laid under the cement soil. 2 The composite geotextile is laid in one layer. In the transverse direction of the dike cross section, the geotextile and the geogrid are integrally made according to the structure size of the cross section. In the longitudinal direction of the dike, the geotextile and the geogrid can be laid in a single piece or jointed into a single piece on site. The jointing size is determined according to the manufacturing and construction conditions. The adjacent two pieces of the composite geotextile in the axial direction of the dike can be connected by hand sewing or overlapping. The hand sewing uses two rows of nylon threads with a needle spacing of not more than 10 mm. The longitudinal and transverse overlapping widths are 15 m underwater and 1.0 m on land. The sewing width is 0.5 m. The composite geotextile and the geogrid are laid flat, tight and straight without sagging and wrinkling. The laying is performed in sections. After the laying is completed, temporary ballast measures are used for fixation. Cement soil construction: The cement content is 16%. The 28-day compressive strength is not less than 0.8 Mpa. The compaction degree is not less than 0.95. Before the construction of the cement soil, the base is inspected and the surface of the rotten soil and sundries is cleaned. If the base soil is generally loose and the water loss is serious, water is sprinkled and static rolling is performed. Then, the cement soil construction is performed. First, the plain soil is laid by using the frame method to control the amount of plain soil laying. The in-situ moisture content is measured. The moisture content is controlled to be the optimum moisture content + 2-+ 3%. When the moisture content is large, the soil is turned over and dried. When the moisture content is insufficient, water is sprinkled in time. The first layer is laid out to control the edge line. The above is backfilled by 300 mm per layer and the edge slope line is laid out. The excavator is used for turning and mixing. The on-site construction personnel should pay attention to checking whether the mixed material is uniform and whether there are cement lumps or soil lumps. During the next mixing, the mixing width of each time should overlap the mixing width of the last time by 500 mm. The construction personnel record the starting and ending time of the mixing. The cement content is detected by the test personnel on site during the mixing process and at the end of the mixing. The cement content is not less than 16%. The earth of the previous excavation is poured into the mixing area by the backhoe excavator. The earth is pushed flat by the truck. The pushing thickness is maintained at about 24 cm. The in-situ moisture content should be greater than the optimum moisture content by 1-3 percentage points. When the moisture content is small, water is sprinkled. After the soil is soaked for 5-8 hours, whether the moisture content of the soil layer meets the requirements and whether the moisture content of the soil layer is uniform are detected. After the soil layer is qualified, the soil is transported to the backfill area. The cement soil is initially leveled to make the surface flat and the thickness uniform; After the mixture is well mixed, use the excavator to stabilize the surface once. After the stabilization, immediately measure the elevation. For the low-lying areas, use the iron rake to loosen the surface layer by more than 10 cm, and use the freshly mixed mixture to level and compact the surface. Remove the excess mixture directly. Use the small roller or the rammer to compact the surface. Use the fast static pressure for 1 pass, uniform speed and weak vibration for 1 pass, strong vibration for 4-6 passes, and static pressure for the surface. For the areas that cannot be compacted, use the electric impact rammer to compact the surface for 3 passes. After the surface is compacted, sprinkle water to maintain the surface. After 2-3 days of maintenance, spread a layer of soil on the surface to cover and maintain the surface. Closed gas soil construction: The closed gas soil is mainly used in the inner side of the seawall. Special materials such as polyethylene film and polyurethane foam are used to fill the soil to form a gas-tight layer, which prevents the penetration of gas and water in the soil and ensures the air tightness of the space. By adjusting the pressure of the gas in the space, the compactness and stability of the soil can be affected. Increasing the gas pressure can increase the compactness of the soil and improve the bearing capacity. Conduct a detailed survey of the construction area to understand the soil properties, groundwater level, and underground pipeline information. Based on the survey results and engineering requirements, develop a design scheme for the closed gas soil construction, including the depth of soil reinforcement, construction sequence, and preparation of the required construction materials. Clean the surface of the construction area to remove debris and contaminants. Construct a seepage prevention layer on the thickened soil on the surface of the construction area. Install the air-tight layer material on the seepage prevention layer. Close the construction area by fixing the seepage prevention layer and the air-tight layer. In the construction space, gradually increase the gas pressure through the gas compression device to adjust the compactness and stability of the soil. Monitor the gas pressure and soil properties during the construction process and make necessary adjustments based on the monitoring results.

[0036] Step S7, construction of the water-facing slope protection, using concrete four-corner hollow blocks to stack and protect.

[0037] In the embodiment, concrete four-corner hollow blocks are used to stack and protect, with a length of 28.51m, The concrete grade of the four-corner hollow blocks is C40; Before placing the four-legged hollow block surface, check the block stone cushion slope; The placement sequence of the four-legged hollow blocks must follow the bottom-up and side-to-side advancement principle; The four-legged hollow blocks are placed regularly.

[0038] Step S8, the construction of the inner slope and the wave protection wall, including the construction of the wave protection wall and the ground beam.

[0039] In the embodiment, the concrete wave protection wall and the ground beam are cast in situ, and a settlement joint is arranged every 10 meters, the width of the adjacent joint is 20mm, the filler in the joint is polyethylene foam board with a thickness of 20mm, the settlement joints are arranged at the same cross-sectional position, the concrete is commercial concrete, the concrete strength grade of the concrete wave protection wall and the ground beam is C40; The construction of the wave protection wall and the ground beam includes: Steel bar engineering: The incoming steel bars meet the design and specification requirements; the steel bars used in the project are free from knots, bending and other damages; the steel bars are kept clean, free from rust, rust scrapes, oxide scales, oil, soil, paint, concrete dirt and any other materials that may affect the combination between the concrete and the steel bars; the site where the steel bars are stacked is covered, the steel bars are placed on the wooden board and the support pier, and the net distance from the ground is greater than 15cm; The cushion block for maintaining the steel bar protection layer is made of concrete with the same strength, color and mixing ratio as the cast-in-place concrete; The placement of the steel bars requires to ensure the correct position and firmly fix, the support for protecting the position of the steel bars is the same steel bar or other appropriate steel products; the wire for binding the steel bars is soft iron wire with a diameter of 20-22#, and the end of the wire is bent into the concrete at the intersection of all the steel bars; In the construction, the straight steel bars are cut to the required length, and the cold bending is performed by experienced steel bar workers; the cutting and cold bending of the steel bars are strictly performed according to the relevant provisions of the construction specification; The steel bar welding operation is performed according to the provisions of the steel bar welding and acceptance specification; The bound steel bars cannot be bent or straightened before or after the concrete is poured; Formwork engineering: The formwork adopts light combined steel formwork, which is ordered from the manufacturer; when the concrete is vibrated, the formwork joint must meet the requirement of no slurry leakage, sponge strips are additionally arranged at the joint of the formwork, and the sponge strips are flush with the inner surface of the formwork; the fastening adopts φ48 steel pipe fasteners, and the steel pipe fasteners are supported by the counter-bolts for the reinforced concrete shaft wall; The formwork is installed according to the true shape and size of the permanent project shown in the drawings; the formwork is installed to be correct in position, stable in support, has sufficient support struts and braces, and can withstand the lateral pressure generated during the pouring and vibration of the concrete, and is not affected by the weather; when the formwork is erected, the formwork is uniformly and flatly arranged, so that the concrete surface at the joint is flat and uniform; the joint design of the formwork is in harmony with the appearance of the structure, so that the vertical and horizontal joints are kept flat; the formwork cannot be directly connected with the structural steel bars, nor can it be connected with the construction scaffold, so as to avoid the deformation and misplacement of the formwork; The inner surface of the formwork shall be coated with a release agent to prevent sticking to the concrete and facilitate stripping; during the coating operation, the adjacent concrete structure or reinforcement shall not be contaminated; before pouring the concrete, sawdust, shavings, dust, other debris and stagnant water shall be removed from the forming surface of the formwork; The embedded parts or reserved pipes shall be fixed on the formwork at the position and elevation required by the drawings; before pouring the concrete, the position and number of the embedded parts and reserved holes shall be determined in accordance with the design Figure 1 and shall be securely installed; The concrete strength at the time of formwork removal shall meet the relevant requirements of the design specification; the structure of the removed formwork and support shall be able to bear the full service load after the concrete strength reaches the design concrete strength grade; Concrete work: The concrete shall be centrally mixed at the mixing plant, transported by concrete transport vehicles and hoisted into the formwork by cranes; the following requirements and precautions shall be met during construction: Before pouring, the formwork, reinforcement and embedded parts shall be inspected and the debris in the formwork, stagnant water and dirt on the reinforcement shall be cleaned; if the formwork has gaps, it shall be tightly filled and the inner surface of the formwork shall be coated with a release agent; Before pouring, the uniformity and slump of the concrete shall be checked; The scaffold used for pouring the concrete shall facilitate the personnel and tools to go up and down and must ensure safety; The concrete shall be poured in layers with certain thickness, sequence and direction; the upper layer of concrete shall be poured before the initial setting or remoldability of the lower layer of concrete; the thickness of each layer of concrete shall not exceed 40 cm; During the pouring of the concrete, the insert-type vibrating rod shall be used for vibration; the vibration shall meet the following requirements: When using the insert-type vibrating rod, the moving distance shall not exceed 1.5 times the effective radius of the vibrating rod and the distance to the adjacent structure shall be kept at 5-10 cm; the vibrating rod shall be inserted into the lower layer of concrete by 5-10 cm; the vibrating rod shall be withdrawn while vibrating after each vibration; the vibrating rod shall not collide with the formwork, reinforcement and other embedded parts; Each vibration site shall be vibrated until the concrete at the site is compacted; the compacted concrete shall stop sinking, no air bubbles shall come out, the surface shall be flat and smooth; The pouring of the concrete shall be continuous; if interrupted, the interruption time shall be less than the initial setting time or remoldability time of the previous layer of concrete; the allowable interruption time shall be determined by test; if the interruption time exceeds the allowable time, quality assurance measures shall be taken or the work joint shall be treated; During the pouring of the concrete, the following shall be observed: The position of the embedded bolts and reserved holes shall be observed at any time; if found to be shifted, they shall be corrected in time; The forming equipment of the reserved holes shall be timely loosened; During the pouring process, attention should be paid to the support conditions of the formwork, support, etc. A special person should be arranged to check. If there is deformation, displacement or subsidence, it should be corrected and reinforced immediately, and the pouring can continue after treatment; During the pouring process or after the pouring is completed, if there is a lot of water seepage on the surface of the concrete, measures should be taken to remove the water without disturbing the poured concrete. When continuing to pour the concrete, the cause should be found out and measures should be taken to reduce water seepage; After the concrete pouring is completed, the exposed surface of the concrete should be promptly trimmed, smoothed, and the second pass should be polished or roughened after the setting; After the concrete reaches a certain strength, it should be promptly watered and maintained. When the weather is dry, it should also be covered and maintained.

[0040] Step S9, embankment road surface construction.

[0041] In the embodiment, the embankment road surface is constructed by mixing AC-25 type coarse-grained asphalt concrete and AC-13 type fine-grained asphalt concrete, the thickness of the coarse-grained asphalt concrete is 60mm, and the thickness of the fine-grained asphalt concrete is 40mm; The unconfined compressive strength of the cement stabilized macadam should be greater than 3.0MPa after 7 days, the compaction degree should be greater than 97%, and the crushed value of the macadam should be not greater than 35%; The C30 shoulder stone has a specification of 300mmx400mmxl000mm; When paving the cushion layer, the loose paving thickness should be controlled, and the loose paving coefficient is determined according to the on-site test paving; the mixture paving should use a paving machine or other applicable paving machinery and be assisted by manual leveling, and it is strictly forbidden to use a tooth to pull the leveling; During the paving, one-time leveling should be achieved. If frog phenomenon occurs due to the concentration of coarse aggregates in some local areas after paving, a small amount of cement mortar can be used for embedding and then rolling; it is strictly forbidden to supplement a thin layer on the cement mortar formed by rolling; The rolling time of the mixture should be close to the best water content; the rolling should be light at first and then heavy, and the rolling should be from the road edge to the road center, and a smooth wheel or a vibrating roller can be used, and the wheel trace overlap is 30cm for double wheels and 1 / 2 of the rear wheel width for three wheels; It is strictly forbidden to make the turning, turning back, sudden braking, etc. of the roller or the feeding vehicle on the road section that has just been compacted or is being rolled; The asphalt concrete should be mechanically paved, and the machinery should have a device for automatically or semi-automatically adjusting the paving thickness and leveling; The asphalt concrete construction temperature should be above 5°, and the construction should be performed when the subgrade settlement is not greater than 1.5cm; During the asphalt concrete construction, the paving thickness and flatness should be mastered, the mineral aggregate segregation should be avoided, the paving and rolling temperatures should be controlled, and the rolling should be performed to the required compactness.

[0042] Step S10, land pipe construction, including construction layout survey, trench excavation, pipe trench dewatering, excavation and pipe foundation, steel pipe transportation, steel pipe welding, steel pipe internal and external corrosion, steel pipe laying and installation, trench backfilling and pipe crossing treatment.

[0043] In the embodiment, the construction layout survey comprises the following steps: Before construction, the position and elevation of the pipeline to be connected are re-measured, and when the re-measured elevation is consistent with the design elevation, the construction can be carried out; at the same time, the existing pipeline and structures are measured before construction, and necessary construction protection measures are taken during construction, and the relevant pipeline property units are coordinated and supervised; The theodolite and RTK are used to encrypt the pipeline line center stake according to the coordinate points handed over by the first party, and the control stake is set up, and the elevation is introduced to the nearby buildings by the level, and the obvious marks are made; The direction method is adopted, and the straight ruler is used to determine the trench excavation boundary line, and the excavation line is scattered with lime; Trench excavation: Manual excavation is adopted, and manual slope repair is adopted, the excavation slope is not less than 1:1, the earthwork of the excavated trench is piled on both sides of the trench, the distance between the piled earth and the excavation boundary line is not less than 1.5m, the soil layer at the bottom of the excavated trench is ensured not to be disturbed, and about 20cm protection layer is reserved for the trench excavation and cleaned by manual; During the trench excavation process, the trench bottom elevation and center line are measured and controlled at any time to prevent over-excavation or deviation; When excavating the trench, the pipeline and cable are protected, and timely report is made to the relevant units, and timely solution and treatment are made to prevent accidents and losses; The soil layer of the excavated trench should be firm, if loose backfilling soil, humus soil or stone blocks are encountered, they should be treated, the scattered soil should be dug out and re-filled, the backfilling thickness is not more than 20cm for rolling and ramming, the humus soil should be dug and replaced with gravel material and rolled and rammed, and if stone blocks are encountered, the site should be cleaned and replaced with better quality soil for backfilling; Pipe trench dewatering and excavation: When the terrain is undulating, the site is first leveled; When the base trench excavation approaches the design elevation of the base, it is appropriate to reserve 150-300 soil layer, which is removed before the next process; The distance of the earth pile to the excavation line should be determined according to the excavation depth, and should not be less than the trench depth; The pipe construction requires that one section is excavated and one section is buried, which cannot expose or soak the base trench, and waterproof measures should be taken during the rainy season construction; When the excavation depth of the foundation pit is less than 3m, it is recommended to adopt slope excavation or support, the slope is determined according to the single buried depth and the surrounding soil conditions, and if necessary, measures such as plain concrete facing are taken; The buildings and pipelines with an excavation depth of 3m are required to be observed according to the reference monitoring value table; Pipe foundation: The pipeline foundation adopts cement soil foundation, cement content is 16%, 28-day compressive strength is not less than 0.8Mpa, compaction degree is not less than 0.95; Pipeline foundation construction process: Base treatment→measurement and lofting→mixing→soil transportation and soil filling→leveling→size and elevation adjustment→compaction→maintenance; Specific construction process ① Base treatment: Before cement soil construction, the base layer needs to be inspected and the surface of the rotten soil and sundries is cleaned. If the base soil is generally loose and water loss is serious, it must be watered and then static rolling is carried out, and then cement soil construction is carried out. First, the soil is paved with frame method to control the amount of soil paving, and the water content is measured on site. The water content is controlled at the optimum water content +2-+3%. When the water content is large, it is turned over and dried. When the water content is insufficient, water is sprayed in time. ② Measurement and lofting: The first layer is laid out with control lines, and the above is backfilled by 300mm per layer, and the slope line is laid out; ③ Mixing: The excavator is used for mixing. The on-site construction personnel should pay attention to check whether the mixed material is uniform, whether there are cement lumps or soil lumps, and prevent the occurrence of soil interlayer. When mixing the next section, the mixing width of each time should overlap the last mixing width by 500mm to ensure that the material is fully mixed. Construction personnel must record the start and end time of mixing. During the mixing process and at the end, the cement content is detected on site by the test personnel. The cement content is not less than 5%; ④ Soil transportation and soil filling: The backhoe excavator is used to pour the soil excavated in the previous period into the mixing area (when filling, the plant roots and unsuitable soil in the soil must be removed), and the shovel truck is used to push the filling to be flat. The pushing thickness is maintained at about 24cm. The water content is measured on site to meet more than 1~3 percentage points of the optimum water content (the surface of sandy soil loses water faster), and when the water content is small, the water cart must be used to spray water. After the material is soaked for 5~8 hours, it is detected whether the water content of the soil meets the requirements and whether the water content of the soil layer is uniform. After passing the test, it is transported to the backfilling area; ⑤ Leveling: The cement soil is preliminarily leveled after paving to make the surface flat and the thickness uniform. This process is beneficial to the uniform paving of cement; ⑥ Size and elevation adjustment: After the mixture is mixed uniformly, the excavator is used for stable pressure; after stable pressure is completed, elevation measurement is carried out immediately. For local low-lying places, the surface layer is loosened more than 10cm with an iron rake, and new mixed material is used for leveling and compaction. The excess mixed material is directly scraped off, and thin layer patching phenomenon should not occur; ⑦ Compaction: Small roller or rammer is used for compaction; the rolling adopts fast static pressure 1 time, uniform speed weak vibration 1 time, strong vibration 4-6 times, and static pressure surface collection method. For places where rolling cannot be carried out, electric impact rammer is used for compaction, and the compaction frequency is set to 3 times; ⑧Maintenance: Sprinkle water on the surface of the roller to maintain health, and cover the surface with a layer of soil after 2-3 days of maintenance; To ensure the formation of cement soil strength in the later stage, heavy equipment is prohibited from passing after the formation of cement soil; Steel pipe transportation: After the pipe is transported to the construction site, the joint acceptance procedure is carried out; after the acceptance, 80t crawler crane is used for unloading; during construction, try to unload the steel pipe to the welding group operation surface at one time, and place it according to the requirements when the conditions are not met; The following regulations will also be followed during transportation and hoisting: During transportation, stacking, hoisting and other processes, it is necessary to prevent collision, extrusion and other inappropriate handling methods, and also to prevent damage to the anticorrosion layer. More attention should be paid to the protection of the pipe opening part to prevent deformation; When loading and unloading the steel pipe, hoisting should be adopted, and it is not allowed to roll down or slide off the car. When placing the steel pipe, it should be placed according to the installation sequence and leave a passageway for easy batch use. When placing, consider that there is a corrosion-resistant layer outside the pipe, and considering the characteristics of the welding site, sand (without sharp stones) is evenly laid under the pipe to avoid damage to the corrosion-resistant layer; When hoisting the steel pipe, the surface should be fixed with no-friction fixed lifting belt, hooks, pressing plates and other metal parts. The hooks should not hook the inner surface of the steel pipe, but should be tied firmly with ropes. When the steel pipe is lifted, the ropes should maintain a certain angle to ensure that the deformation force of the steel pipe is minimized; The equipment used for hoisting steel pipes and other steel pipe materials should be in good condition, and under any circumstances, the steel pipes should not be dropped, collided, freely rolled or dragged along the ground; If necessary, the steel pipe and pipe fittings should be supported off the ground and tightly wedged with shock-absorbing pads; Steel pipe welding: The steel pipe uses hot-rolled steel strip as pipe blank, and is formed by spiral forming at room temperature. The spiral seam is welded by automatic submerged arc welding method, and the inner and outer submerged arc welds are not less than one each; The steel pipe is allowed to have a steel strip butt weld, and the distance between the steel strip butt weld and the end of the steel pipe is not less than 300mm. The steel strip butt weld is welded by submerged arc welding method, and the inner and outer submerged arc welds are not less than one each. Two short pipes of the same steel grade are welded into one steel pipe, and the length of each short pipe is not less than 2.0m; The spiral welds on both sides of the circumferential weld are staggered, and the circumferential distance is not less than 200mm; Steel pipe internal and external anticorrosion: The outer side of the pipe-encased concrete, foundation cushion and other parts in contact with external water and soil: anticorrosion uses non-toxic and solvent-free epoxy anticorrosive paint with a thickness of ≥500μm; The outer anticorrosion of the buried pipe on land and the pipe through the embankment adopts molten combined epoxy powder coating with a total dry film thickness of not less than 600μm, and the anticorrosion coating is completed in the pipe factory; Before painting, the coating performance test is carried out in the laboratory; In the welding seam or once there are a few pinholes or area less than 25cm 2 of unqualified parts in the outer anti-corrosion coating of steel pipe and pipe fittings, local repair is carried out, the anti-corrosion coating of steel pipe welding seam adopts artificial liquid coating method, 3-4 coats with total thickness not less than 800μm, and curing agent is added when using fusion epoxy powder or solvent-free epoxy heavy-duty anti-corrosion coating; The anti-corrosion method of steel pipe in the sea-land connecting section adopts two-base four-sides epoxy anti-corrosion coating with thickness≥600μm; The inner anti-corrosion of the sea outlet pipe adopts non-toxic and solvent-free epoxy anti-corrosion coating with thickness≥400μm, and the production and processing process adopts automatic high-pressure airless spraying to form a film at one time, the solid content of epoxy anti-corrosion coating is more than 98%, which belongs to heavy-duty anti-corrosion coating; The surface treatment of steel pipe and pipe fittings adopts shot blasting; Steel pipe laying and installation: Check the trench; Pipe arrangement: for steel pipes with diameter of 1800mm, generally arrange them on the ground along the trench edge before lowering into the trench, and the length of pipe arrangement is determined according to the size of pipe diameter and the performance of pipe lowering machinery, and each pipe section is preferably 30-40m, and the method of pipe arrangement is generally to place the two ends of the pipe on a square wood with a section of 150×150mm and a length of 1-1.5m; Pipe lowering: mechanical pipe lowering is usually used, and the automobile type or caterpillar type crane is usually used for mechanical pipe lowering, and the protection of the pipe and the anti-corrosion layer should be done well during pipe lowering, especially the contact part between the pipe and the rope, and if the mechanical pipe lowering is used for large pipe diameter, a special soft belt can be used; the pipe lowering method for the land section is combined hoisting, and the land section is first welded on the trench edge to form a long pipe section, and then lowered into the trench; Pipe lowering method: automobile type or caterpillar type crane is used for pipe lowering, and during pipe lowering, the crane moves along the direction of the trench, lifts the pipe, rotates the lifting arm to move the pipe above the trench, and then slowly puts it into the trench; the position of the crane should be kept at a certain distance from the trench edge, and the pipe end is tied with a rope, which is pulled by a person to adjust the direction at any time; Elevation control during pipe lowering: after the pipe is lowered into the trench, due to the heavy weight of the single pipe, the thickness of the cushion layer is certain and the leveling is good, the level meter measures the elevation of each pipe, and the height difference between the pipe head and the pipe tail is controlled within 20mm, and when the next pipe is lowered into the trench, the settlement of the previous pipe is measured, and then the alignment is carried out; Trench backfilling: After the hydraulic test is qualified, it should be backfilled in time. There should be no accumulated water in the trench during backfilling. The sand soil excavated above the pipe top can be used for backfilling, but the scouring soil containing organic matter and shell impurities or the soil containing gravel with a particle size greater than 15 cannot be used for backfilling. According to the soil properties and compaction tools, the water content of the backfilling soil should be controlled near the optimum water content to meet the compaction requirements of the pipe trench backfilling; The trench backfilling within 70 cm above the pipe top must be backfilled and compacted by hand. The heavy compaction machines cannot be used for compaction within 40 cm above the pipe top. When the acceptance and pipe installation are completed, the earthwork backfilling can be carried out. The earthwork backfilling uses the excavated soil in the pipe trench. The backfilling height is 1 m 3 The excavator excavates and backfills, and the artificial leveling is used. Before the trench backfilling, the owner's representative, the supervision representative and other relevant parties should inspect and qualify it. The pipe depth should meet the design requirements. The pipe top elevation measurement should be completed, and the data should be accurate. The pipe in the trench should not be suspended. The accumulated water in the trench should be removed. If the corrosion layer of the pipe is found to be scratched or broken, it should be repaired immediately. During the trench backfilling, the pipe bottom should be filled first, then the both sides of the pipe are filled, and then the backfilling is carried out to 0.5 m above the pipe top (the untested joint should be left out). The backfilling soil within 0.3 m above the pipe top and both sides of the pipe should not contain gravel, bricks, silt, organic soil, garbage and other impurities. A small amount of stone with a diameter not greater than 0.1 m is allowed in the backfilling soil above 0.3 m from the pipe top. The backfilling soil should be compacted in layers, and the thickness of each layer is 0.2-0.3 m. The filling soil within 0.5 m above the pipe top and both sides of the pipe must be compacted layer by layer. The height difference of the compacted surface of both sides should not exceed 0.3 m. When the filling soil exceeds 2.0 m above the pipe top, the mechanical compaction is used, and the thickness of each layer is 0.25-0.4 m. The backfilling around the well chamber should be carried out at the same time as the pipe trench backfilling. When it is not convenient to carry out at the same time, a step-shaped joint should be left. The backfilling and compaction around the well chamber should be carried out symmetrically along the center of the well chamber, and the compaction should not be missed. The backfilling material should be closely attached to the well wall after compaction. The materials such as lime soil, sand and gravel should be used for backfilling around the well chamber within the road surface range, and the backfilling width should not be less than 400 mm. The water content of the backfilling soil should be controlled near the optimum water content. Before the hydraulic test, the pipe sides and the pipe top above 0.5 m can be backfilled except for the joint. After the pressure test is qualified, the other parts are backfilled in time. Pipe crossing treatment: If the plastic pipe is on the top and the reinforced concrete pipe is on the bottom, the distance between the bottom of the upper pipe and the outer top of the lower pipe is greater than 0.5 m, then no treatment is required. If the reinforced concrete pipe is on the top and the plastic pipe is on the bottom, the bottom of the upper pipe to the top of the lower pipe is greater than 0.5m, the sand is filled in the range of the upper pipe groove, the length is 1.5 times the outer diameter of the upper pipe, the bottom of the upper pipe to the top of the lower pipe is less than or equal to 0.5m, the lower plastic pipe is wrapped with concrete, and the length is 5m on each side of the upper pipe.

[0044] Step S11, cofferdam dismantling construction.

[0045] In the embodiment, the inner cofferdam is a reinforced concrete cofferdam located on land, and the outer cofferdam is a mud-filled pipe bag soil cofferdam located in the beach section, both of which do not have the risk of water operation. The inner cofferdam is selected to be broken by a cannon head excavator, and the outer cofferdam is selected to be dismantled by a backhoe excavator and a dump truck in cooperation with earth excavation. Specific embodiments: The Ningbo petrochemical economic and technological development zone tail water deep sea discharge No. 2 pipe project (sea section) newly builds a sea section total length of about 5.07km (of which the sea section is about 5km), and the design scale is 190,000 m 3 / d, the pipeline passes through the west navigation hole channel of Jintang Bridge, and is constructed by using a single steel pipe DN1800 sea area immersed tube construction method (of which the discharge section pipe diameter DN1000-DN1800 is about 240m).

[0047] The pipeline starts from the high well of the built discharge No. 1 pipe on land, passes through the seawall, and reaches the deep sea discharge port along the sea route.

[0048] The main points are to first build an inner cofferdam (reinforced concrete retaining wall construction) on the inner side of the dam and build an outer cofferdam (mud-filled pipe belt and high-pressure jet grouting pile construction) on the water-facing side of the dam, complete the cofferdam construction, and then carry out the main body construction of the dam section (wave protection wall dismantling, dam excavation, pipe foundation treatment, steel pipe section welding, and pipe outer concrete protection, and dam backfilling), followed by cement soil, closed gas earthwork, water-facing side, inner slope protection, and wave protection wall and road surface construction. After the completion of the dam section construction, the land pipe and cofferdam dismantling construction is carried out.

[0049] The dam construction of the present application uses DN1800 Q235B steel pipe with a wall thickness of 20mm, including: ①K0+00-K0+73.29, which is the land section trenching and pipe burying construction, which is connected from the existing No. 1 discharge pipe high well north valve well to the landing point, with a length of 73.29m.

[0050] ②K0+73.29-K0+88.69, which is the dam section trenching and pipe burying construction, which formally passes through the seawall from the landing point to the wave protection wall sea side outer vertical boundary, with a length of 15.4m.

[0051] ③K0+88.69-K0+117.20, which is the dam section trenching and pipe burying construction, which is then protected and buried by stacking concrete four-corner hollow blocks, with a length of 28.51m.

[0052] (4) K0+117.20-K0+136.01, the construction is to be built in the mud section, and the connection between the section through the dike and the sea section is made at K0+128.85, with a length of 18.81 m.

[0053] According to the construction drawing and design description, a reasonable construction scheme is adopted to improve the engineering quality, reduce the investment cost, shorten the construction period, and successfully complete the construction task of the dike-related project.

[0054] Finally, it should be noted that the above is only the preferred embodiment of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method of laying a marine pipeline across an existing embankment, characterised in that, Comprise: Step S1, construction preparation, including technical preparation, material preparation, construction site preparation, construction machinery and equipment and construction force arrangement; Step S2, engineering survey, including control point survey, center line, axis measurement, temporary benchmark measurement and measurement instrument detection; Step S3, cofferdam construction, including reinforced concrete retaining wall cofferdam construction, high pressure jet grouting pile cofferdam construction and mud pipe bag cofferdam construction; Step S4, through the embankment pipe main body engineering construction, including clearing and measuring line, wave protection and road removal, embankment excavation, steel pipe welding installation, pipe foundation treatment, concrete square bag and backfill and embankment repair; Step S5, embankment filling, including rolling embankment; Step S6, cement soil, closed air soil, including anti-seepage soil construction, geotextile laying, cement soil construction and closed air soil construction; Step S7, the construction of the slope protection on the water side, using concrete four corner hollow block stacking protection buried; Step S8, inner slope, wave protection wall construction, including wave protection wall and ground beam construction; Step S9, embankment road construction; Step S10, land pipe construction, including construction lofting measurement, trench excavation, pipe trench dewatering, excavation and pipe foundation, steel pipe transportation, steel pipe welding, steel pipe internal and external corrosion prevention, steel pipe laying installation, trench backfill and pipe crossing treatment; Step S11, cofferdam removal construction.

2. A method of laying a marine pipeline across an existing embankment according to claim 1, characterised in that, In the step S1, the technical preparation includes: Organize relevant technical personnel and construction teams, according to the embankment construction drawings, make good construction arrangement, and according to the meteorological natural conditions of the engineering project area, the construction site and the hydrogeological conditions, make good construction plane arrangement; Material preparation includes: According to the requirements of quality assurance plan, construction organization design work plan, construction machinery and equipment plan and material supply plan, implement the main material source, optimize the supplier, and do well in ordering and purchasing; Construction site preparation includes: Inquire the basic situation of local material supply market, and reconnaissance the construction site, contact with the designated department of the first party, implement the construction water and electricity connection position, at the same time, according to the specific situation of construction site, lay construction water and electricity pipeline, set up office on site, build material and equipment warehouse, reasonably arrange personnel housing and living facilities; Construction machinery and equipment includes: According to the construction machinery and equipment demand plan and construction requirements, organize construction machinery and equipment into the field.

3. A method of laying a marine pipeline across an existing embankment according to claim 1, wherein, In the step S2, the control point survey includes: Review the measurement disclosure of surveying and designing department; According to the owner's guide post, add control network according to construction needs; According to the site conditions, all control points are selected in the high ground outside the construction operation range, and the visibility of each control point is good; After the control point is selected, the control point coordinates in the whole engineering range are determined through actual measurement and closure adjustment calculation; wherein, the control network is measured and set by 2 second level total station; The center line, axis measurement includes: Taking the center control pile provided by the surveying and mapping institute as the reference, the center line of the pipeline is measured and placed, and the well number provided by the design drawing is used to place the accurate center position by total station; The temporary benchmark measurement includes: According to the national leveling point provided by the survey design department, the construction temporary leveling point is set, and the distance of the temporary leveling point is not greater than 200m without adding a turning point for height measurement; Wherein, the temporary leveling point and the design leveling point are closed for retesting, and the temporary leveling point is set outside the construction range, and the temporary leveling point is rechecked at intervals; The detection of the measuring instrument includes: Before the project starts, all measuring instruments entering the construction site are inspected, and after passing the inspection, they are used within the valid period.

4. A method of laying a marine pipeline across an existing embankment according to claim 1, wherein, In step S3, the steel reinforced concrete retaining wall inner cofferdam is divided into two forms, one is high wall form, and the other is low wall form; The construction process of the steel reinforced concrete retaining wall inner cofferdam includes: measurement and layout, earthwork excavation and ramming, cushion construction, foundation steel production and installation, foundation formwork erection, foundation concrete pouring, wall formwork erection, wall concrete pouring, concrete curing, formwork removal and backfilling.

5. A method of laying a marine pipeline across an existing embankment according to claim 1, wherein, In step S3, the construction of the high-pressure rotary jet pile outer cofferdam includes: construction preparation, measurement and layout, grouting process, control of cement dosage, grouting treatment, consolidation body shape control and ensuring the strength of the pile top.

6. A method of laying a marine pipeline across an existing embankment according to claim 1, wherein, In step S3, in the construction of the filled pipe bag outer cofferdam, the main body of the outer cofferdam adopts the filled pipe bag soil cofferdam, and the high-pressure rotary jet pile is used as the impermeable body on the side close to the dam.

7. A method of laying a marine pipeline across an existing embankment according to claim 1, wherein, In step S4, the table cleaning and measurement and layout include: table cleaning, measurement and layout, surface measurement control, following requirements, wave protection dike and road removal, dike excavation, steel pipe welding and installation, pipe foundation treatment, concrete block, concrete block steel production and installation, concrete block formwork erection, concrete block concrete pouring, concrete block concrete curing and backfilling and dam repair.

8. A method of laying a marine pipeline across an existing embankment according to claim 1, wherein, In step S5, the rolling filling includes taking soil→unloading soil→paving soil→rolling→inspection.

9. A method of laying a marine pipeline across an existing embankment according to claim 1, wherein, In step S7, the four-corner hollow block is used to stack and protect the buried length of 28.51m, The four-corner hollow block concrete grade is C40; Before placing the four-corner hollow block facing, the block stone cushion slope should be checked; The placing sequence of the four-corner hollow block must follow the principle of from bottom to top and from one side to the other side; The four-corner hollow block is placed regularly; In step S8, the concrete wave protection wall and the ground beam are poured in place, and a settlement joint is set every 10m, the adjacent joint is 20mm wide, the filling material in the joint is polyethylene foam board with a thickness of 20mm, the settlement joint should be set at the same cross-section position, the concrete is commercial concrete, and the concrete strength grade of the concrete wave protection wall and the ground beam is C40; In step S9, the dam top pavement is constructed by mixing AC-25 type coarse-grained asphalt concrete and AC-13 type fine-grained asphalt concrete, the thickness of the coarse-grained asphalt concrete is 60mm, and the thickness of the fine-grained asphalt concrete is 40mm; The 7-day unconfined compressive strength of the cement stabilized gravel should be greater than 3.0MPa, the compaction degree should be greater than 97%, and the crushed value of the gravel should be not greater than 35%; The C30 shoulder stone specification is 300mmx400mmxl000mm.

10. A method of laying a marine pipeline across an existing embankment according to claim 1, wherein, In step S10, construction layout measurement: before construction, the position and elevation of the pipeline to be connected are retested, and before construction, the existing pipeline and structure are measured; Trench excavation: manual excavation and manual slope repair; Trenching and excavation: when the foundation trench is excavated to the design elevation, 150-300 soil layers are reserved and removed before the next process; when the foundation pit is excavated to a depth of less than 3m, it is recommended to use slope excavation or support, and the slope is determined according to the single buried depth and surrounding soil conditions; Pipeline foundation: the pipeline foundation uses a cement-soil foundation with a cement content of 16%, and the 28-day compressive strength is not less than 0.8Mpa, and the compaction degree is not less than 0.95; Pipeline foundation construction process: foundation treatment → measurement and lofting → mixing → soil transportation and soil filling → leveling → size and elevation adjustment → compaction → maintenance; Steel pipe transportation: after the pipe material is transported to the construction site, it is subjected to joint acceptance according to the procedure; Steel pipe welding: the steel pipe uses hot-rolled steel strip as the pipe blank, and the spiral seam is welded by automatic submerged arc welding; Steel pipe internal and external corrosion: non-toxic and solvent-free epoxy anticorrosive paint is used for corrosion protection, and the steel pipe and pipe surface treatment use shot blasting; Steel pipe laying and installation: check the trench, pipe and pipe laying; among them, the pipe laying uses mechanical pipe laying; Trench backfilling: after the hydraulic test is passed, it should be backfilled in time, and there should be no water in the foundation trench during backfilling, and the sand soil above the pipe top can be used for backfilling, but the scouring soil containing organic matter and shell impurities, or the soil containing gravel with a particle size greater than 15 cannot be used for backfilling; Pipeline crossing treatment: if the plastic pipe is on the top and the reinforced concrete pipe is on the bottom, the bottom of the upper pipe to the outer top of the lower pipe is >0.5m, then no treatment is needed; if the reinforced concrete pipe is on the top and the plastic pipe is on the bottom, the bottom of the upper pipe to the outer top of the lower pipe is >0.5m, the range of the upper pipe trench above the lower pipe top is filled with sand, the length is 1.5 times the outer diameter of the upper pipe on each side, the bottom of the upper pipe to the outer top of the lower pipe is ≤0.5m, and the lower plastic pipe is wrapped with concrete, and the length is 5m on each side out of the upper pipe; In the step S11, the inner cofferdam is a reinforced concrete cofferdam located on land, and the outer cofferdam is a filled mud pipe bag soil cofferdam located in the tidal flat section, both of which do not have water operation risk, the inner cofferdam is selected to be broken by a bucket excavator, and the outer cofferdam is selected to be demolished by a backhoe excavator and a self-unloading truck.

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