Construction method for controlling settlement of concrete pipeline under soft soil foundation

Abstract

The invention provides a settlement control construction method for a concrete pipeline under a soft soil foundation. The settlement control construction method comprises the steps of geological investigation, pipeline laying, trench excavation and foundation pile construction in a trench. A broken stone hardcore is laid, and a pipeline supporting base is embedded; mounting and connecting the concrete pipeline and the like. The method has the beneficial effects that by determining the soft soil section, anti-sedimentation treatment is specifically carried out on the section which is prone to sedimentation, so that the construction difficulty and the construction cost can be reduced; according to the method, a supporting pile body is laid and constructed at the bottom of a pipeline laying groove which is prone to sedimentation, and the pile body can improve the supporting capacity of a soft soil foundation to a concrete pipeline; and the pipeline supporting base can also inject cement paste into the broken stone hardcore through the grouting pipe, the settled pipeline supporting base is lifted through the injection pressure, meanwhile, the cement paste and the broken stone hardcore are solidified into concrete blocks, the supporting force of the broken stone hardcore on the concrete pipeline is enhanced, and therefore the service life of the concrete pipeline is further prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of pipeline construction, in particular to a construction method for controlling the settlement of a concrete pipeline under a soft soil foundation. Background Art

[0002] Soft soil foundations are often encountered in the construction of municipal engineering and water conservancy projects. When laying concrete pipes on soft soil foundations, concrete pipes are prone to settlement due to the high compressibility and low strength of soft soil. This will not only affect the normal use of the pipes, but may also cause serious problems such as pipe rupture and leakage, bringing huge safety hazards and economic losses to the project. In order to prevent the settlement of pipes laid in the above-mentioned soft soil foundation, the existing construction method usually lays concrete in the entire construction tunnel to form a hard support layer. This method can reduce the possibility of settlement of soft soil foundations to a certain extent, but it will also greatly increase the construction difficulty and construction cost, and the construction period will also be extended. After the settlement of the soft soil foundation occurs, the difficulty of repairing the settlement of the concrete pipe will also be greatly increased. Summary of the invention

[0003] In view of this, the installation accuracy of concrete pipes is improved, their settlement capacity and anti-lateral displacement capacity are enhanced, while the construction cost of concrete pipes is reduced and their construction efficiency is improved. The present invention provides a construction method for controlling the settlement of concrete pipes under soft soil foundation, comprising the following steps:

[0004] S1: Conduct geological survey on the construction site to determine the soft soil area;

[0005] S2: Determine the pipeline laying route based on the geological survey results, dig a pipeline laying trench, and mark the part of the pipeline laying trench passing through the soft soil area as the soft soil section;

[0006] S3: construct foundation piles vertically at the bottom of the pipeline laying trench in the marked soft soil section;

[0007] S4: laying a gravel cushion layer at the bottom of the pipeline laying trench in the soft soil section, making a pipeline support base, burying the pipeline support base in the gravel cushion layer, and supporting the bottom of the pipeline support base on the foundation pile; the pipeline support base has a hollow cavity inside, and is provided with a grouting hole and an overflow hole connected to the hollow cavity;

[0008] S5: supporting the concrete pipe on a pipe support base, connecting adjacent ends of the concrete pipes, and sealing the connection;

[0009] S6: Connect the grouting pipe to the grouting hole of the pipe support base, use the backfill soil to backfill the road laying trench, and bury the connected concrete pipe in the backfill laying trench.

[0010] S7: Regularly detect the settlement of the pipeline support base, and inject concrete slurry into the grouting pipe on the pipeline support base where the settlement exceeds the set threshold, so as to restore the pipeline support base to its original height.

[0011] Furthermore, the foundation pile includes two parallel pile bodies, and the bottom of the pipeline support base is provided with two legs, and the two legs are respectively supported on the two pile bodies.

[0012] Furthermore, a limiting groove is provided on the top of each pile body, and the lower end of the leg portion of the pipeline support base is limited in the limiting groove.

[0013] Furthermore, a limiting seat is provided above the pipeline support base, an arc-shaped positioning groove is provided on the upper surface of the limiting seat, and the lower part of the concrete pipeline is positioned and supported in the positioning groove.

[0014] Furthermore, the pile body is a cement mixing pile, and the process of constructing the pile body in step S2 includes the following steps:

[0015] S31: using a pile mixing machine to drive a drill rod to drill a mixing hole at the bottom of the pipeline laying trench to a predetermined depth;

[0016] S32: inject cement slurry into the drill rod, the pile mixing machine drives the drill rod to rotate and spray out cement slurry, and during the rotation of the drill rod, the height of the drill rod is raised, the drill rod injects cement slurry into the mixing hole, and mixes the cement slurry with the soil in the mixing hole until the drill rod is lifted out of the mixing hole.

[0017] Furthermore, after the cement mixing piles are constructed in step S3, the following steps are also included: excavating a certain depth at the bottom of the pipeline laying trench and backfilling a permeable layer, the permeable layer is made of medium-coarse sand, the mud content of the medium-coarse sand shall not be greater than 5%, the thickness of the permeable layer is 150-300mm, the permeable layer is compacted after backfilling, and the pile body height exceeds the height of the permeable layer.

[0018] Furthermore, the grouting pipe in step S6 is a reinforced concrete cast-in-place pipe, and the orifice of the grouting hole is pre-buried with connecting steel bars. The pouring process of the grouting pipe in step S6 is:

[0019] Step S61: making a steel cage mesh of a cylindrical structure, and connecting the steel cage mesh with the connecting steel bars pre-embedded in the orifice of the grouting hole;

[0020] Step S62: installing the template of the double-sleeve structure on the pipeline support base so that the steel cage mesh is located in the gap between the double sleeves of the template;

[0021] Step S63: injecting concrete slurry into the gap between the double sleeves of the template, and after the concrete slurry solidifies, disassembling the template to form the grouting pipe.

[0022] Furthermore, after the grouting pipe is poured in step S6, a cover is installed on the top of the grouting pipe to close the top opening of the grouting pipe to prevent rainwater from flowing into the pipe support base through the grouting pipe.

[0023] Furthermore, in step S6, the backfilling process of the backfill soil body adopts a layered backfilling and layered compaction method, the thickness of each backfill layer exceeds 300 mm, and the compaction times are not less than 3 times.

[0024] Furthermore, the thickness of the gravel cushion layer is 200-500 mm, and the height of the upper surface of the gravel cushion layer exceeds the height of the overflow hole on the pipeline support base.

[0025] The beneficial effects of the construction method for controlling the settlement of concrete pipes under soft soil foundation of the present invention are as follows:

[0026] (1) This method detects soft soil sections before excavating the construction trench for the concrete pipe, identifies and marks the sections that are prone to settlement behind the concrete pipe, and takes targeted anti-settlement measures for the sections that are prone to settlement. This can reduce the construction difficulty, construction cost, and improve construction efficiency while ensuring the quality of concrete pipe laying.

[0027] (2) This method lays supporting piles at the bottom of the pipeline laying trench where settlement is prone to occur. The piles can greatly improve the support force of the soft soil foundation on the concrete pipe, thereby reducing the possibility of settlement of the soft soil foundation, thereby improving the quality of concrete pipe laying, preventing the concrete pipe from being damaged or failing due to geological settlement, and extending the service life of the concrete pipe.

[0028] (3) This method uses a concrete pipe support base at the bottom of the pipe laying trench to support the concrete pipe, and the pipe support base is supported on a pile body. A gravel cushion layer is also laid under the pipe support base. The pile body and the gravel cushion layer jointly support the concrete pipe to disperse the pressure of the concrete pipe on the soft soil body, which can further prevent the soft soil from settling. In addition, the pipe support base can also inject cement slurry into the gravel cushion layer through a grouting pipe, and use the injection pressure to lift the settled pipe support base. At the same time, the cement slurry and the gravel cushion layer solidify into a concrete block, thereby strengthening the support force of the gravel cushion layer on the concrete pipe, thereby further extending the service life of the concrete pipe.

[0029] (4) This method casts a grouting pipe before backfilling the pipeline laying trench, so that the grouting pipe mouth extends to the ground surface, which can provide a cement slurry injection channel for the subsequent recovery treatment of the concrete pipe, greatly reducing the construction difficulty and cost of the concrete pipe settlement treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1The present invention is a flowchart of a method for controlling the settlement of a concrete pipe under a soft soil foundation according to an embodiment of the present invention.

[0031] Figure 2 It is a schematic diagram of an installation structure of a concrete pipe in a construction method for controlling the settlement of a concrete pipe under a soft soil foundation according to an embodiment of the present invention.

[0032] Figure 3 yes Figure 2 Cross-section view of the pipe support base.

[0033] In the above figure: 1-concrete pipe, 2-gravel cushion layer, 3-permeable layer, 4-pile body, 5-pipe support base, 51-leg part, 52-grouting hole, 53-overflow hole, 54-limiting seat, 55-positioning groove, 6-grouting pipe, 61-cover body. DETAILED DESCRIPTION

[0034] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0035] Please refer to Figures 1 to 3 ,in Figure 1 The present invention provides a construction method for controlling the settlement of a concrete pipe under a soft soil foundation, and the construction method for controlling the settlement of a concrete pipe under a soft soil foundation comprises the following steps:

[0036] S1: Conduct geological survey on the construction site to understand the distribution range, thickness, and physical and mechanical properties of the soft soil foundation to determine the soft soil area; prepare corresponding materials and construction equipment at the construction site, such as concrete pipes, cement, sand, stone and other construction materials; equip with excavators, loaders, cranes, compactors, levels and other construction equipment to ensure that the equipment has good performance and meets the construction requirements.

[0037] S2: Determine the pipeline burial route based on the geological survey results, so that the pipeline burial route avoids the above-mentioned soft soil area as much as possible, and ensure that the length of the pipeline burial route passing through the soft soil area is as short as possible; determine the pipeline burial route, excavate the pipeline laying trench according to the pipeline burial route, and mark the part of the pipeline laying trench passing through the soft soil area as the soft soil section; the bottom height of the above-mentioned excavated pipeline laying trench is kept consistent, so that the axis of the concrete pipe laid therein can be guaranteed to be horizontal, thereby facilitating the connection and sealing of the concrete pipe.

[0038] S3: constructing foundation piles vertically at the bottom of the pipeline laying trench in the marked soft soil section; in this embodiment, the foundation piles include two parallel pile bodies 4, and the pile bodies are cement mixing piles.

[0039] The process of constructing the pile body in step S3 includes the following steps:

[0040] S31: using a pile mixing machine to drive a drill rod to drill a mixing hole at the bottom of the pipeline laying trench to a predetermined depth; wherein the drill rod is a hollow drill rod, and a mixing blade and an injection hole are provided at the bottom of the drill rod. During the drilling of the mixing hole, the mixing blade breaks up the soil in the mixing hole and leaves it in the mixing hole;

[0041] S32: Cement slurry is injected into the drill rod from the top of the drill rod, and the pile mixing machine drives the drill rod to rotate and spray out cement slurry. During the rotation of the drill rod, the drill rod is raised, and the drill rod injects cement slurry into the mixing hole, and the cement slurry and the soil in the mixing hole are mixed by the mixing blade until the drill rod is lifted out of the mixing hole. After the cement slurry and the soil in the mixing hole solidify, the pile body 4 is formed.

[0042] S4: Lay a gravel cushion layer 2 at the bottom of the pipeline laying trench in the soft soil section, and make a pipeline support base 5. The pipeline support base 5 can be a prefabricated component or a cast-in-place component. The pipeline support base 5 is buried in the gravel cushion layer 2, and the bottom of the pipeline support base 5 is supported on the foundation pile; the pipeline support base 5 has a hollow cavity inside, and the pipeline support base 5 is provided with a grouting hole 52 and an overflow hole 53 connected to the hollow cavity;

[0043] S5: Support the concrete pipe 1 on the pipe support base 5, connect the adjacent ends of the concrete pipes 1, and seal the connection; the ends of the concrete pipes 1 are connected by rubber ring interfaces, welding, etc. to ensure that the concrete pipes are tightly connected without leakage. After the concrete pipes are connected, use measuring tools such as levels to accurately control the elevation and slope of the concrete pipes 1 to ensure that the concrete pipes 1 are installed accurately.

[0044] S6: Connect the grouting pipe 6 to the grouting hole 52 of the pipe support base 5, use the backfill soil to backfill the road laying trench, and bury the connected concrete pipe 1 in the backfill road laying trench. The backfill soil should be selected with well-graded sand, gravel, etc. as the backfill material, and silt, frozen soil, expansive soil and other poor fillers should not be used.

[0045] S7: Regularly detect the settlement of the pipeline support base 5, and inject concrete slurry into the grouting pipe 6 on the pipeline support base 5 whose settlement exceeds the set threshold, so that the pipeline support base 5 returns to its original height. The concrete slurry injection process uses a high-pressure cement grouting pump, and the high-pressure cement is injected into the pipeline support base 5 and overflows from the overflow hole 53. The cement slurry overflowing from the overflow hole 53 at the bottom of the pipeline support base 5 provides an upward force for the pipeline support base 5, thereby causing the pipeline support base 5 to return to its original height, and the cement slurry overflowing from the overflow hole 53 is mixed with the crushed stone in the crushed stone cushion layer 2 and solidified into a concrete block, which supports the pipeline support base 5 as a whole to prevent the pipeline support base 5 from continuing to settle.

[0046] Preferably, two legs 51 are provided at the bottom of the pipeline support base 5, and the two legs 51 are respectively supported on the two pile bodies 4. A limiting groove is provided at the top of each pile body 4, and the lower end of the leg 51 of the pipeline support base 5 is limited in the limiting groove. The structure of the limiting groove and the leg 51 can prevent the pipeline support base 5 from lateral displacement.

[0047] Furthermore, a limit seat 54 is provided above the pipe support base 5, and an arc-shaped positioning groove 55 is provided on the upper surface of the limit seat 54. The lower part of the concrete pipe 1 is positioned and supported in the positioning groove 55, and the positioning groove 55 ensures that the concrete pipe 1 is accurately installed.

[0048] Furthermore, after the cement mixing pile is constructed in step S3, the following steps are also included: a certain depth is excavated at the bottom of the pipeline laying trench, and a water-permeable layer 3 is backfilled, the material of the water-permeable layer 3 is medium-coarse sand, the mud content of the medium-coarse sand shall not be greater than 5%, the thickness of the water-permeable layer 3 is 150-300mm, the water-permeable layer 3 is compacted after backfilling, and the top height of the pile body 4 exceeds the height of the water-permeable layer 3. The water-permeable layer 3 prevents the pipeline support base 5 from slipping after water accumulates at the bottom.

[0049] Furthermore, the grouting pipe 6 in step S6 is a reinforced concrete cast-in-place pipe, and the orifice of the grouting hole 52 is pre-buried with connecting steel bars. The pouring process of the grouting pipe 6 in step S6 is:

[0050] Step S61: making a steel cage mesh of a cylindrical structure, and connecting the steel cage mesh with the connecting steel bars pre-embedded in the opening of the grouting hole 52;

[0051] Step S62: Install the template of the double sleeve structure (inner and outer sleeve structure) on the pipe support base 5 so that the steel cage mesh is located in the gap between the double sleeves of the template; Step S63: Inject concrete slurry into the gap between the double sleeves of the template. After the concrete slurry solidifies, remove the template to form the grouting pipe 6.

[0052] The grouting pipe 6 is a reserved grouting channel for the subsequent grouting recovery of the pipeline support base 5, so as to reduce the construction difficulty and cost of the concrete pipe settlement treatment.

[0053] Preferably, after the grouting pipe 6 is poured in step S6, a cover body 61 is installed on the top of the grouting pipe 6 to close the top opening of the grouting pipe 6 to prevent rainwater from being injected into the pipeline support base 5 through the grouting pipe 6.

[0054] Preferably, the backfilling process of the backfill soil in step S6 adopts a layered backfilling and layered compaction method, the thickness of each backfill layer exceeds 300 mm, and the number of compaction times is not less than 3 times.

[0055] Preferably, the crushed stone cushion layer 2 has a thickness of 200-500 mm, and the height of the upper surface of the crushed stone cushion layer 2 exceeds the height of the overflow hole 53 on the pipeline support base 5 .

[0056] In this document, the directional words such as front, back, top, and bottom are defined by the positions of the components in the drawings and the positions of the components relative to each other, and are only for the sake of clarity and convenience in expressing the technical solution. It should be understood that the use of the directional words should not limit the scope of protection claimed in this application.

[0057] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A construction method for controlling the settlement of a concrete pipe under a soft soil foundation, characterized in that: The steps include: S1: Conduct geological survey on the construction site to determine the soft soil area; S2: Determine the pipeline laying route based on the geological survey results, dig a pipeline laying trench, and mark the part of the pipeline laying trench passing through the soft soil area as the soft soil section; S3: construct foundation piles vertically at the bottom of the pipeline laying trench in the marked soft soil section; S4: laying a gravel cushion layer at the bottom of the pipeline laying trench in the soft soil section, making a pipeline support base, burying the pipeline support base in the gravel cushion layer, and supporting the bottom of the pipeline support base on the foundation pile; the pipeline support base has a hollow cavity inside, and is provided with a grouting hole and an overflow hole connected to the hollow cavity; S5: supporting the concrete pipe on a pipe support base, connecting adjacent ends of the concrete pipes, and sealing the connection; S6: Connect the grouting pipe to the grouting hole of the pipeline support base, use the backfill soil to backfill the road laying trench, and bury the connected concrete pipe in the road filling laying trench; S7: Regularly detect the settlement of the pipeline support base, and inject concrete slurry into the grouting pipe on the pipeline support base where the settlement exceeds the set threshold, so as to restore the pipeline support base to its original height.

2. A construction method for controlling the settlement of a concrete pipe under a soft soil foundation according to claim 1, characterized in that: The foundation pile comprises two parallel pile bodies, and two supporting legs are arranged at the bottom of the pipeline support base, and the two supporting legs are respectively supported on the two pile bodies.

3. A construction method for controlling the settlement of a concrete pipe under a soft soil foundation according to claim 2, characterized in that: A limiting groove is arranged on the top of each pile body, and the lower end of the leg portion of the pipeline support base is limited in the limiting groove.

4. The method for controlling the settlement of a concrete pipe under a soft soil foundation according to claim 1, characterized in that: A limiting seat is also provided above the pipeline support base, and an arc-shaped positioning groove is provided on the upper surface of the limiting seat. The lower part of the concrete pipeline is positioned and supported in the positioning groove.

5. The method for controlling the settlement of a concrete pipe under a soft soil foundation according to claim 2, characterized in that: The pile body is a cement mixing pile, and the process of constructing the pile body in step S3 includes the following steps: S31: using a pile mixing machine to drive a drill rod to drill a mixing hole at the bottom of the pipeline laying trench until a predetermined depth is reached; S32: inject cement slurry into the drill rod, the pile mixing machine drives the drill rod to rotate and spray out cement slurry, and during the rotation of the drill rod, the height of the drill rod is raised, the drill rod injects cement slurry into the mixing hole, and mixes the cement slurry with the soil in the mixing hole until the drill rod is lifted out of the mixing hole.

6. A construction method for controlling the settlement of a concrete pipe under a soft soil foundation according to claim 5, characterized in that: After the cement mixing pile is constructed in step S3, the following steps are also included: excavating a certain depth at the bottom of the pipeline laying trench and backfilling a permeable layer, wherein the material of the permeable layer is medium-coarse sand, the mud content of the medium-coarse sand is not more than 5%, the thickness of the permeable layer is 150-300mm, the permeable layer is compacted after backfilling, and the height of the top of the pile body exceeds the height of the permeable layer.

7. A construction method for controlling the settlement of a concrete pipe under a soft soil foundation according to claim 2, characterized in that: The grouting pipe in step S6 is a reinforced concrete cast-in-place pipe, and the orifice of the grouting hole is pre-buried with connecting steel bars. The pouring process of the grouting pipe in step S6 is: Step S61: making a steel cage mesh of a cylindrical structure, and connecting the steel cage mesh with the connecting steel bars pre-embedded in the orifice of the grouting hole; Step S62: installing the template of the double-sleeve structure on the pipeline support base so that the steel cage mesh is located in the gap between the double sleeves of the template; Step S63: injecting concrete slurry into the gap between the double sleeves of the template, and after the concrete slurry solidifies, disassembling the template to form the grouting pipe.

8. A construction method for controlling the settlement of a concrete pipe under a soft soil foundation according to claim 7, characterized in that: After the grouting pipe is poured in step S6, a cover is installed on the top of the grouting pipe to close the top opening of the grouting pipe to prevent rainwater from flowing into the pipe support base through the grouting pipe.

9. The method for controlling the settlement of a concrete pipe under a soft soil foundation according to claim 1, characterized in that: In step S6, the backfilling process of the backfill soil body adopts the method of layered backfilling and layered compaction, the thickness of each backfill layer exceeds 300mm, and the compaction times are not less than 3 times.

10. A construction method for controlling the settlement of a concrete pipe under a soft soil foundation according to claim 1, characterized in that: The thickness of the crushed stone cushion layer is 200-500 mm, and the height of the upper surface of the crushed stone cushion layer exceeds the height of the overflow hole on the pipeline support base.

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