Vertical upward pipe jacking construction method in hard plastic clay layer

Abstract

The invention relates to the technical field of tunnel engineering in geotechnical engineering, and discloses a vertical upward pipe jacking construction method in a hard plastic clay layer, which comprises the following main construction steps: constructing a cushion layer, grouting a tunnel vault, burying a plastic pipe in a ground surface guide hole, assembling an arc-shaped bracket, mounting a jacking fixing frame, injecting water into a soil body for softening, jacking a pipe joint, cutting the ground surface soil body and the like. After the arc-shaped support is assembled, the arc-shaped stand columns incline towards the outer side, the construction space under the jacking machine is not occupied, and outward transportation of muck and carrying and stuffing of pipe joints are facilitated; the pipe joint is restrained and stopped based on a clamping device on the arc-shaped support; water is injected in advance to soften the cut soil body in front of the pipe jacking machine during vertical upward jacking construction, so that the cutting resistance of the pipe jacking machine in hard plastic clay is small, the surrounding environment of the jacking pipe is protected as much as possible, and the safety and reliability of vertical upward jacking pipe construction are improved.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel engineering in geotechnical engineering, and in particular to a vertical upward pipe jacking construction method in a hard plastic clay layer. Background Art

[0002] Affected by factors such as urban traffic and underground pipelines, it is common to use trenchless shield construction for the construction of urban integrated pipeline corridors. In order to ensure ventilation and the needs of shield pipeline corridor maintenance, it is often necessary to dig vertical shafts inside the integrated pipeline corridor. Traditional vertical shaft construction often adopts open-cut construction, but the open-cut construction period is long and the cost is relatively high, which has a greater impact on the environment, surrounding traffic and residents' lives.

[0003] In this context, trenchless vertical pipe jacking technology has developed rapidly. Vertical pipe jacking technology refers to a method in which an opening is opened above a comprehensive pipe gallery or tunnel, and a pipe jacking machine cuts the soil vertically upward to complete the vertical riser construction in the process of continuous soil discharge. However, the existing vertical pipe jacking technology has the following limitations.

[0004] (1) During vertical pipe jacking, the deadweight of the pipe section and the frictional force acting on the pipe section are directed downward, which means that when the pipe sections are connected, the pipe sections that have been pushed forward need to be effectively restrained and fixed in the vertical direction, and the insertion and connection of the subsequent new pipe sections should not be hindered in space. For example, the limit rod mentioned in the patent application publication number CN110388215A may hinder the insertion of the subsequent new pipe sections in space; the thrust device mentioned in the patent application publication number CN116856946A may be difficult to provide sufficient thrust resistance.

[0005] (2) In the traditional horizontal pipe jacking construction process, grouting and water injection can be used to soften the soil in front and around the pipe jacking machine to reduce the frictional resistance during the jacking construction process. However, in the vertical jacking construction process, if grouting and water injection are performed in front of the pipe jacking machine or around the pipe segments, the grouting slurry flows downward under the action of gravity, which obviously cannot improve the properties of the soil in front of the pipe jacking machine. For example, the water sprayed from the water jet holes mentioned in the patent application publication number CN114607834A may have difficulty reaching the front of the pipe jacking machine, that is, the upper soil layer.

[0006] (3) When vertical pipe jacking construction is carried out inside an underground tunnel, the construction working surface is narrow and the available space is small. The equipment or devices proposed in some technologies do not take into account the convenience of transportation, assembly, and construction in a narrow space and the coordination of space avoidance, resulting in difficulties in actual operation. For example, the anti-retraction mechanism proposed in patent application publication number CN114215525A may cause spatial conflict and interference to the pipe jacking construction.

[0007] In particular, when constructing vertical pipe jacking in hard plastic clay layers, the soil strength is high and the frictional resistance is large. The difficulty in cutting the soil makes the jacking more difficult. Measures need to be taken to reduce the cutting resistance during the vertical jacking process of the pipe jacking machine. It can be seen that it is necessary to solve the above-mentioned limitations in the vertical pipe jacking construction process, develop technical methods for vertical pipe jacking construction, especially in hard plastic clay, and promote the advancement of vertical pipe jacking technology in tunnel engineering. Summary of the invention

[0008] In order to solve the above-mentioned technical problems of limitations in the vertical upward pipe jacking construction process, the present invention provides a vertical upward pipe jacking construction method in a hard plastic clay layer.

[0009] The present invention is implemented by the following technical scheme: A vertical upward pipe jacking construction method in a hard plastic clay layer, comprising the following steps:

[0010] S1. Construction preparation: Before starting construction, the hard plastic clay layer at the construction site is explored and analyzed, such as through drilling sampling and physical and chemical property testing, so as to understand the hardness, density, plasticity and viscosity characteristics of the soil layer. At the same time, the construction plan is determined in combination with the influence of surface buildings, pipelines and surrounding environment. According to the construction plan, the relevant equipment, tools, materials and the prepared arc-shaped brackets are transported to the vicinity of the location where the vertical upward jacking construction of the existing underground tunnel is planned to be carried out, and water and electricity are connected to the vicinity of the location;

[0011] S2. Construction cushion: In the existing tunnel arch bottom section where vertical jacking construction is to be carried out, a release agent is applied, steel bars are tied and concrete is poured to form a reinforced concrete cushion;

[0012] S3. Tunnel vault grouting: Based on the grouting holes and hoisting holes of the pipe segments, grouting is performed around the vault of the existing tunnel where vertical jacking construction is to be carried out along the center line of the pipe segment to be jacked in to form a grouting body. The grouting material is cement slurry. The grouting range is not less than 1.5 times the diameter of the pipe segment to be jacked in, and the length of the grouting pipe is not less than 1.0m;

[0013] S4. Bury plastic pipes through holes on the ground: Drill holes on the ground along the center line of the pipe section to be inserted until the distance from the tunnel arch is no more than 2.0m. After drilling and cleaning the holes, insert the plastic pipes into the holes, fill the inside of the plastic pipes with medium-coarse sand, and evenly set water outlet holes around the plastic pipes;

[0014] S5. Assemble the arc bracket: Based on the bottom beam and the top beam, assemble the two processed arc brackets on the cushion layer in the tunnel below the center line of the proposed jacking pipe segment;

[0015] S6. Breaking the tunnel vault and jacking construction position: Break the existing tunnel structure around the tunnel vault along the center line of the pipe section to be jacked to form a hole, so that the range of the hole is larger than the outer contour diameter of the pipe section;

[0016] S7. Install the jacking fixture: install the jacking fixture on the top of the assembled arc bracket, so that the center line of the steel ring plate on the jacking fixture coincides with the center line of the pipe segment to be jacked, support the formwork around the jacking fixture, and inject cement slurry into the jacking fixture through the grouting holes, so that the gap between the jacking fixture and the tunnel vault is densely filled with grouting without water seepage;

[0017] S8. Install the pipe jacking machine: With the help of the clamping device and the vertical jack installed on the arc support, fix the pipe jacking machine and the pipe segment inside the arc support in the vertical direction. The center line of the pipe jacking machine and the pipe segment coincides with the center line of the designed pipeline. The head of the pipe jacking machine passes through the steel ring plate of the fixed frame and contacts with the upper soil.

[0018] S9. Soil injection and softening: Before the jacking construction begins, water is injected into the plastic pipe to pre-soften the soil cut in front of the pipe jacking machine during the vertical jacking construction, so that the soil can be loosened and the soil can be loosened to ensure the smooth advancement of the jacking pipe;

[0019] S10. Pipe segment jacking operation: Under the jacking force of the vertical jack and the cutting action of the pipe jacking machine, the pipe segment is gradually jacked upward. During the jacking process, the clamping device installed on the arc bracket is used to constrain and fix the jacked pipe segment, and the pipe segments are inserted and connected in sequence below, so that each pipe segment is connected and lengthened one by one and pushed vertically upward into the soil;

[0020] S11. Cutting the surface soil: When the head of the pipe jacking machine is 2.0m to 3.0m away from the surface, use the equipment to cut the soil on the surface along the center line of the pipe segment to form a soil cutting surface. The depth of the soil cutting surface shall not be less than 1.5m, and the distance between the soil cutting surface and the center line of the pipe segment shall be greater than the radius of the pipe segment by 20cm to 30cm;

[0021] S12. Continue the jacking operation mentioned in step S10 until the pipe jacking machine is pushed out of the ground surface, dismantle the pipe jacking machine and various components, clean the working surface, and complete the vertical upward pipe jacking construction.

[0022] As a further improvement of the above scheme, when the soil is softened by water injection in step S9, the water injection volume and the pre-injection time should be controlled according to the permeability coefficient of the soil layer, so that the soil being cut directly above the pipe jacking machine has been soaked with water when the pipe jacking machine is vertically jacking upward. When the jacking operation stops, the water injection should also be stopped.

[0023] As a further improvement of the above scheme, the pipe jacking machine adopts a segmented advancement method during the jacking operation. After advancing a certain distance, it will pause in stages, then check the soil conditions, and make appropriate adjustments to the jacking pipe to ensure that the thrust and advancement speed are always within an appropriate range, thereby reducing the impact on the equipment and soil layer and ensuring construction quality and safety.

[0024] As a further improvement of the above scheme, under the cutting action of the pipe jacking machine, the hard plastic clay layer is cut into granular or muddy state, which is convenient for slag discharge. The slag discharge is carried out by mixing the soil and water into mud through a pipe, which is pumped to the ground through a mud pump and then discharged or backfilled after purification, so that it can effectively avoid earth backlog and settlement problems.

[0025] As a further improvement of the above scheme, after completing the vertical upward jacking construction in step S12, it is necessary to conduct a quality inspection on the pipeline to ensure the integrity and stability of the pipeline. The inspection content includes but is not limited to the joints, wall thickness and sealing of the pipeline. At the same time, combined with the particularity of the hard plastic clay layer, it is necessary to monitor the settlement of the soil layer around the pipeline to prevent impact on surrounding buildings or infrastructure.

[0026] As a further improvement of the above scheme, the arc-shaped bracket is welded by a bottom longitudinal beam, an arc-shaped column, and a top longitudinal beam, and the two arc-shaped brackets are connected and fixed by a bottom cross beam, a top cross beam, and bolts with pre-set matching bolt holes.

[0027] As a further improvement of the above scheme, the upper and middle parts of the arc-shaped bracket are welded and assembled through a hanger, a supporting beam, a supporting plate and a reaction plate to form a matching mechanism with the clamping device. Slots are provided on both sides of the supporting plate. The reaction plate is welded between two arc-shaped columns. The clamping device can move along the supporting plate under the action of a horizontal jack.

[0028] As a further improvement of the above scheme, the clamping device is welded by a bottom plate, a top force plate, a vertical plate and an arc plate. The inner diameter of the arc plate is equal to the outer diameter of the pipe segment. The width and height of the bottom plate are slightly smaller than the net width and net height between the slots on both sides of the support plate. After the bottom plate is inserted between the slots on both sides of the support plate, it can slide relative to the support plate without detaching.

[0029] As a further improvement of the above scheme, after the bottom plate in the clamping device is inserted between the two side grooves on the support plate, the clamping device can slide relatively along the support plate under the action of the horizontal jack, and the bottom of the horizontal jack acts on the reaction plate, so that the top of the horizontal jack acts on the top force plate of the clamping device.

[0030] As a further improvement of the above scheme, the jacking fixing frame is welded by a horizontal enclosure, a vertical enclosure and a steel ring plate, the inner diameter of the steel ring plate is 3.0 cm to 10.0 cm larger than the outer diameter of the pipe segment, and no less than 4 grouting holes are evenly arranged on the horizontal enclosure, and no less than 4 bolt holes are symmetrically arranged on the outer side of the vertical enclosure, and the bolt holes can be connected to each other based on the bolts and the matching bolt holes on the top longitudinal beam.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The bracket inside the tunnel is assembled from two arc-shaped brackets and a jacking fixed frame. The weight and volume of a single component are small, which is convenient for transportation inside the tunnel. After assembly, the arc-shaped column tilts outward and does not occupy the construction space directly under the jacking machine, which is convenient for the transportation of debris and the transportation and insertion of pipe sections. The arc-shaped bracket is easy to assemble and disassemble and can be used repeatedly. After assembly, the arc-shaped bracket has a large overall rigidity and can meet the strength and rigidity requirements of the jacking operation.

[0033] 2. The present invention is based on the fact that the clamping device is installed on the arc-shaped bracket, which is convenient for assembly and disassembly; under the action of the horizontal jack, the clamping device can slide relatively along the support plate, and then can tightly hold the pipe section, effectively restrain and fix the pipe section that has been pushed in, and does not hinder the insertion of subsequent pipe sections in space.

[0034] 3. Based on the grouting holes and hoisting holes of the pipe segments, the present invention injects grout around the center line of the proposed jacking pipe section on the tunnel vault to form a grouting body, so that the groundwater around the cave entrance cannot penetrate into the construction working surface, providing the necessary conditions for vertical jacking operations in complex environments.

[0035] 4. The gap between the jacking fixture and the tunnel vault is filled densely with grouting without water seepage. The jacking fixture provides a positioning basis for the subsequent jacking of pipe sections.

[0036] 5. Before the jacking construction begins, water is injected into the plastic pipe so that the soil being cut directly above the pipe jacking machine will be soaked with water when the pipe jacking machine is jacking vertically upward. This has low cost and obvious softening effect, which reduces the difficulty of the pipe jacking machine in cutting the soil during jacking construction and provides convenience for vertical upward pipe jacking construction in soft rock and hard plastic clay.

[0037] 6. When the head of the pipe jacking machine is 2.0m to 3.0m away from the ground surface, use the equipment to cut the soil in all directions along the center line of the pipe section on the ground surface to form a soil cutting surface, so as to prevent the surface soil from being uplifted and sheared under the upward jacking force when the subsequent pipe jacking machine approaches the ground surface, and protect the surrounding environment of the pipe jacking as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a flow chart of the main steps of the proposed construction method;

[0039] Figure 2 3D schematic diagram of the arc bracket Figure 1 ;

[0040] Figure 3 3D schematic diagram of the arc bracket Figure 2 ;

[0041] Figure 4 A three-dimensional diagram of the clamping device Figure 1 ;

[0042] Figure 5 A three-dimensional diagram of the clamping device Figure 2 ;

[0043] Figure 6 3D diagram of the assembly of the arc bracket and the clamping device Figure 1 ;

[0044] Figure 7 3D diagram of the assembly of the arc bracket and the clamping device Figure 2 ;

[0045] Figure 8 It is a detailed drawing of the mutual assembly of the arc bracket and the clamping device;

[0046] Fig. 9 A three-dimensional schematic diagram of the assembly of two arc-shaped brackets;

[0047] Fig.10 It is a three-dimensional schematic diagram of two arc-shaped brackets assembled together to clamp the pipe segment;

[0048] Fig.11 Three-dimensional diagram of the jacking fixture Figure 1 ;

[0049] Fig.12 Three-dimensional diagram of the jacking fixture Figure 2 ;

[0050] Fig.13 It is a three-dimensional schematic diagram of the mutual assembly of the arc support and the jacking fixing frame;

[0051] Fig.14 It is a schematic diagram of the relationship between the jacking fixed frame and the pipe joint;

[0052] Fig.15 This is a three-dimensional schematic diagram of the arc bracket assembled inside the tunnel;

[0053] Fig.16 This is a cross-sectional view of the arc-shaped bracket assembled inside the tunnel;

[0054] Fig.17 It is a three-dimensional schematic diagram of the arc-shaped bracket assembled inside the tunnel and clamping the pipe segment;

[0055] Fig.18 This is the cross-section diagram of the vertical upward jacking construction inside the tunnel;

[0056] Fig.19 This is a three-dimensional schematic diagram of the vertical upward jacking construction inside the tunnel;

[0057] Fig. 20 It is a three-dimensional schematic diagram of a plastic pipe;

[0058] Fig.21 This is a schematic diagram of grouting and construction of cushion layer in the tunnel;

[0059] Fig. 22 It is a schematic diagram of constructing water injection pipe and assembling arc bracket;

[0060] Fig.23 This is a schematic diagram of the installation of the pipe jacking machine;

[0061] Fig.24 It is a schematic diagram of vertical upward jacking operation;

[0062] Fig.25 Schematic diagram of cutting surface soil.

[0063] Description of main symbols:

[0064] 1. Arc bracket; 1a. Bottom longitudinal beam; 1b. Arc column; 1c. Top longitudinal beam; 1d. Hanger; 1e. Support beam; 1f. Support plate; 1g. Reaction plate; 1h. Bolt hole; 1k. Bolt hole; 1m. Bolt hole; 1n. Slot; 2. Clamping device; 2a. Bottom plate; 2b. Force plate; 2c. Vertical plate; 2d. Arc plate; 3. Horizontal jack; 4. Bottom crossbeam; 5. Top crossbeam; 6. Pipe section; 7. Jacking fixture; 7a. Horizontal enclosure; 7b. Vertical enclosure; 7c. Steel ring plate; 7d. Grouting hole; 7e. Bolt hole; 8. Tunnel; 9. Pad; 10. Vertical jack; 11. Pipe jacking machine; 12. Plastic pipe; 12a. Water outlet; 13. Grouting body; 14. Medium-coarse sand; 15. Soil cutting surface; A. Ground surface. DETAILED DESCRIPTION

[0065] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0066] Embodiment 1:

[0067] This embodiment introduces the segment clamping device used in the process of implementing the vertical upward jacking construction method (see Figures 2 to 18 ).

[0068] The main frame of the segment clamping device is assembled from two arc-shaped brackets 1, which are welded from a bottom longitudinal beam 1a, an arc-shaped column 1b, and a top longitudinal beam 1c. The two arc-shaped brackets 1 can be assembled through a bottom cross beam 4 and a top cross beam 5, and are connected by bolts based on pre-set matching bolt holes during assembly.

[0069] Preferably, the bottom longitudinal beam 1a, the arc-shaped column 1b and the top longitudinal beam 1c are hollow square steel structures.

[0070] Figure 2 and Figure 3 A schematic diagram of the three-dimensional structure of the arc bracket 1 is given. Fig. 9 and Fig.10 A schematic diagram of the assembly method of the two arc-shaped brackets 1 is given, where bolt holes 1h are set at both ends of the bottom longitudinal beam 1a, which match the bolt holes at both ends of the bottom cross beam 4 and are connected to each other with bolts, bolt holes 1k are set at both ends of the top longitudinal beam 1c, which match the bolt holes at both ends of the top cross beam 5 and are connected to each other with bolts, and a bolt hole 1m is set in the middle of the top longitudinal beam 1c on the outer side, which matches the bolt hole on the outer side of the jacking fixing frame 7 and is connected to each other with bolts.

[0071] The upper and middle part of the arc-shaped bracket 1 is welded by a suspension rod 1d, a supporting beam 1e, a supporting plate 1f, and a reaction plate 1g to form a matching mechanism for assembling the clamping device 2. Slots 1n are set on both sides of the supporting plate 1f. The reaction plate 1g is welded between the two arc-shaped columns 1b. The clamping device 2 can move along the supporting plate 1f under the action of the horizontal jack 3.

[0072] The clamping device 2 is welded by a bottom plate 2a, a top force plate 2b, a vertical plate 2c, and an arc plate 2d. The inner diameter of the arc plate 2d is equal to the outer diameter of the pipe segment 6. The width and height of the bottom plate 2a are slightly smaller than the net width and net height between the slots 1n on both sides of the support plate 1f. After the bottom plate 2a is inserted between the slots 1n on both sides of the support plate 1f, it can slide relative to the support plate 1f without detaching. That is, the clamping device 2 and the arc bracket 1 are independent components. When needed, the bottom plate 2a of the clamping device 2 can be inserted between the slots 1n on both sides of the support plate 1f.

[0073] Figure 4 and Figure 5 A schematic diagram of the three-dimensional structure of the clamping device 2 is given. Figure 6 to Figure 8 The installation method of the clamping device 2 and the arc-shaped bracket 1 is given.

[0074] After the bottom plate 2a of the clamping device 2 is inserted between the slots 1n on both sides of the support plate 1f, the clamping device 2 can slide relatively along the support plate 1f under the action of the horizontal jack 3, the bottom of the horizontal jack 3 acts on the reaction plate 1g, and the top of the horizontal jack 3 acts on the top force plate 2b of the clamping device 2.

[0075] Preferably, a solid lubricant may be applied to the upper surface of the support plate 1f to facilitate mutual sliding between the upper surface of the support plate 1f and the lower surface of the base plate 2a, thereby reducing the frictional resistance between them.

[0076] When the clamping device 2 is not working, it can slide along the support plate 1f and retract to the outside away from the center line of the pipe segment 6 to be pushed in, and it will not have spatial collision and conflict with the pipe segment 6. When the pipe segment 6 needs to be fixed, the clamping device 2 slides along the support plate 1f toward the pipe segment under the action of the horizontal jack 3 until it holds the pipe segment 6 tightly and makes it unable to move, thereby preventing the constructed pipe segment 6 from retreating, and facilitating the continuous connection of the new pipe segment 6 after the vertical jack 10 retracts. Fig.10 A schematic diagram of the clamping device 2 fixing the pipe segment 6 is given.

[0077] Preferably, a rubber sheet of matching size is pasted on the inner side of the arc plate 2d on the clamping device 2 so that the inner side of the arc plate 2d and the outer side of the pipe segment 6 can be in close contact with each other, thereby increasing the frictional resistance between them and enabling the clamping device 2 to effectively restrain and fix the pipe segment 6, thereby providing a good anti-retraction effect on the pipe segment 6.

[0078] A jacking fixing frame 7 is installed above the arc-shaped bracket 1. The jacking fixing frame 7 is welded by a horizontal enclosure 7a, a vertical enclosure 7b, and a steel ring plate 7c. The inner diameter of the steel ring plate 7c is 3.0 cm to 10.0 cm larger than the outer diameter of the pipe segment 6. No less than 4 grouting holes 7d are evenly arranged on the horizontal enclosure 7a, and no less than 4 bolt holes 7e are symmetrically arranged on the outer side of the vertical enclosure 7b. The bolt holes 7e can be connected to each other based on bolts and matching bolt holes on the top longitudinal beam 1c. Fig.11 and Fig.12 A three-dimensional structural schematic diagram of the jacking fixed frame 7 is given. Figures 13 to 19 A schematic assembly diagram of the jacking fixing frame 7 is given.

[0079] During construction, the gap between the jacking fixture and the tunnel vault is filled densely with the grouting body without water seepage. The jacking fixture provides a positioning basis for the subsequent jacking of the pipe segments. During specific operations, the surfaces of the jacking fixture and part of the tunnel that are in contact with the slurry should be coated with a release agent to facilitate the removal of the grouting body after the construction is completed.

[0080] The bracket assembled from the proposed arc-shaped bracket 1 has the following advantages: the bracket is assembled from two arc-shaped brackets and a jacking fixed frame, a single component is small in weight and volume, and is convenient for transportation inside the tunnel; after assembly, the arc-shaped column is inclined outward and does not occupy the construction space directly below the jacking machine, which is convenient for the transportation of debris, the transportation and insertion of pipe sections; the arc-shaped bracket is easy to assemble and disassemble and can be used repeatedly; after assembly, the arc-shaped bracket has a large overall rigidity and can meet the strength and rigidity requirements of the jacking operation; the clamping device is installed on the arc-shaped bracket and is convenient for assembly and disassembly; under the action of the horizontal jack, the clamping device can slide relatively along the support plate, and then tightly hold the pipe section, effectively restrain and fix the jacked pipe section, and does not hinder the insertion of subsequent pipe sections in space.

[0081] Embodiment 2:

[0082] This embodiment introduces a method for vertically jacking pipes in a hard plastic clay layer, which is characterized by comprising the following steps (such as Figure 1 shown):

[0083] S1: Construction preparation: Before starting construction, the hard plastic clay layer at the construction site is explored and analyzed, such as through drilling sampling and physical and chemical property tests, so as to understand the hardness, density, plasticity and viscosity characteristics of the soil layer. At the same time, the construction plan is determined in combination with the influence of surface buildings, pipelines and the surrounding environment, and the relevant equipment, tools, materials and prepared arc brackets are transported to the vicinity of the location where the vertical upward jacking construction of the existing underground tunnel is planned to be implemented; water and electricity are connected to the vicinity of this location.

[0084] S2: Construction cushion: In the existing tunnel 8 arch bottom section where vertical jacking construction is to be carried out, a release agent is applied, steel bars are tied, and concrete is poured to form a reinforced concrete cushion 9, such as Fig.21 shown.

[0085] The reinforced concrete cushion layer 9 should have sufficient strength and rigidity to ensure that the reaction force during the jacking construction has an effect on the stress and deformation of the existing tunnel 8 within the affected range within the permitted range of the specification. The reinforced concrete cushion layer 9 is a temporary structure and usually needs to be demolished later, so a release agent should be applied to reduce the impact on the existing tunnel 8 during the demolition process.

[0086] S3: Tunnel vault grouting: Based on the grouting holes and hoisting holes of the pipe segments, in the existing tunnel 8 where vertical jacking construction is to be carried out, grouting is performed around the center line of the proposed jacking pipe section 6 to form a grouting body 13. The grouting material is cement slurry. The grouting range is not less than 1.5 times the diameter of the proposed jacking pipe section 6, and the length of the grouting pipe is not less than 1.0m.

[0087] Based on the grouting holes and lifting holes of the pipe segments, grouting is injected around the tunnel arch along the center line of the pipe segment to be jacked into, forming a grouting body, so that the groundwater around the cave entrance cannot penetrate into the construction working surface, providing the necessary conditions for vertical jacking operations in complex environments.

[0088] S4: burying plastic pipes in ground holes: drilling holes on the ground along the center line of the proposed pipe section 6 until the distance from the tunnel 8 arch is no more than 2.0m. After drilling and cleaning the holes, insert the plastic pipe 12 into the holes, and then fill the inside of the plastic pipe 12 with medium-coarse sand 14; water outlet holes 12a are evenly arranged around the plastic pipe 12.

[0089] The plastic tube 12 is constructed as follows Fig. 20 As shown. The outer diameter of the plastic pipe is slightly smaller than the diameter of the lead hole by 3.0 to 5.0 cm. The plastic pipe 12 filled with medium-coarse sand 14 is actually a water injection channel. Water flows along the plastic pipe 12 to the bottom end of the jacking machine 11 excavation position, which plays a role in moistening and softening the soil in front of the jacking machine 11.

[0090] The subsequent pipe jacking machine 11 will touch the plastic pipe 12 during the vertical upward excavation process. The plastic pipe 12 at the contact position will be cut and crushed and discharged together with the slag, and the remaining plastic pipe 12 will continue to play the role of a water seepage channel.

[0091] S5: Assembling the arc support: Based on the bottom crossbeam 4 and the top crossbeam 5, assemble the two processed arc supports 1 on the cushion layer 9 in the tunnel 8 below the center line of the proposed jacking pipe section 6, such as Fig. 22 shown.

[0092] S6: Breaking the tunnel vault and jacking construction position: At the tunnel 8 vault, the existing tunnel structure is broken around the center line of the pipe segment 6 to be jacked to form a hole, so that the range of the hole is larger than the outer contour diameter of the pipe segment 6.

[0093] Grouting has been carried out around the holes in the early stage13, so if there is groundwater around the holes, when the holes are broken, a large amount of water will not flow out from the breach and affect subsequent construction.

[0094] S7: Install the jacking fixture: Install the jacking fixture 7 on the top of the assembled arc-shaped bracket 1, so that the center line of the steel ring plate 7c on the jacking fixture 7 coincides with the center line of the pipe segment 6 to be jacked, support the formwork around the jacking fixture 7, and inject cement slurry into the jacking fixture 7 based on the grouting holes 7d, so that the gap between the jacking fixture 7 and the arch of the tunnel 8 is filled with the grouting body and no water seepage occurs.

[0095] The jacking fixture 7 provides a positioning basis for the subsequent jacking construction of the pipe segment.

[0096] S8: Install the pipe jacking machine: With the help of the clamping device 2 and the vertical jack 10 installed on the arc support 1, fix the pipe jacking machine 11 and the pipe segment 6 in the vertical direction inside the arc support. The center line of the pipe jacking machine 11 and the pipe segment 6 coincides with the center line of the designed pipeline. The head of the pipe jacking machine 11 passes through the steel ring plate 7c of the fixed frame 7 and contacts with the upper soil. Fig.23 shown.

[0097] The power for the upward movement of the pipe jacking machine 11 and the pipe segment 6 is provided by the vertical jack 10. Considering the influence of stress concentration, a steel plate should be laid under the vertical jack 10, or other auxiliary measures should be adopted to ensure that its influence on the cushion layer 9 and the tunnel 8 is within the allowable range of the specification.

[0098] S9: Soil injection and softening: Before the jacking construction begins, water is injected into the plastic pipe 12 to pre-soften the soil cut in front of the pipe jacking machine during the vertical upward jacking construction.

[0099] When water injection to soften the soil is implemented, the injection volume and pre-injection time should be controlled according to the soil permeability coefficient, so that the soil being cut directly above the pipe jacking machine has been soaked by the injected water when the jacking machine is jacking vertically upward; the water injection should also be stopped when the jacking operation stops.

[0100] Preferably, the range of water injection above the jacking working face to the surroundings should not be greater than twice the diameter of the pipe segment 6, so as to reduce the impact of water injection on the surrounding environment.

[0101] Water is injected into the plastic pipe before the jacking construction begins, so that the soil being cut directly above the jacking machine will be soaked with water when the jacking machine is jacking vertically upward. This is low-cost and has a significant softening effect, which reduces the difficulty of the jacking machine cutting the soil during jacking construction and provides convenience for vertical upward jacking construction in soft rock and hard plastic clay.

[0102] S10: Pipe segment jacking operation: Under the jacking force of the vertical jack 10 and the cutting action of the pipe jacking machine 11, the pipe segment 6 is gradually jacked upward. During the jacking process, the clamping device 2 installed on the arc support 1 constrains and fixes the jacked pipe segment 6, and the pipe segments 6 are inserted and connected in sequence below, so that each pipe segment is connected and lengthened one by one and pushed vertically upward into the soil. Fig.24 shown.

[0103] Generally, in horizontal jacking construction, the slag needs to be transported to the working pit for discharge through scrapers, conveyor belts and other devices. However, in vertical jacking construction, scrapers, conveyor belts and other devices are no longer needed. Only a flexible slag discharge pipe is required in the pipe section. The crushed slag enters the slag discharge pipe and gradually falls into the tunnel 8 under the action of gravity for loading and discharge.

[0104] S11: Cutting the surface soil: When the head of the pipe jacking machine 11 is 2.0m to 3.0m away from the surface, use the equipment to cut the soil on the surface along the center line of the pipe segment 6 to form a soil cutting surface 15. The depth of the soil cutting surface 15 is not less than 1.5m. The distance between the soil cutting surface 15 and the center line of the pipe segment 6 should be greater than the radius of the pipe segment 6 by 20cm to 30cm. Fig.25 shown.

[0105] When the pipe jacking machine 11 is close to the ground surface, if the thickness of the overlying soil layer is small, the overlying soil layer may be pushed up and sheared under the action of the jacking force, causing uplift deformation and damage to a large area of ​​soil.

[0106] The soil within a certain range above the jacking pipe is cut by equipment (such as a circular saw) to form a soil cutting surface 15, so as to control the impact range of the jacking construction on the surface soil and protect the surrounding environment of the jacking pipe as much as possible.

[0107] Preferably, the soil cutting surface 15 is in the shape of a regular quadrilateral circumscribed to the outer contour of the pipe segment 6 , and the vertical distance from the center line of the pipe segment 6 to the regular quadrilateral should be greater than the radius of the pipe segment 6 by 20 cm to 30 cm.

[0108] S12: Continue the jacking operation mentioned in step S10 until the pipe jacking machine 11 is pushed out of the ground surface; dismantle the pipe jacking machine 11 and various components, clean the working surface, and complete the vertical upward pipe jacking construction.

[0109] The proposed vertical upward pipe jacking construction method in the hard plastic clay layer makes the cutting resistance of the pipe jacking machine in the hard plastic clay smaller, the components in the spatial arrangement are coordinated and avoided with each other, and the pipe sections in place can be effectively fixed and stopped, thereby improving the safety and reliability of the vertical upward pipe jacking construction.

[0110] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A method for vertically jacking pipe in a hard plastic clay layer, characterized in that: The following steps are involved: S1. Construction preparation: Before starting construction, the hard plastic clay layer at the construction site is explored and analyzed, such as through drilling sampling and physical and chemical property testing, so as to understand the hardness, density, plasticity and viscosity characteristics of the soil layer. At the same time, the construction plan is determined in combination with the influence of surface buildings, pipelines and surrounding environment. According to the construction plan, the relevant equipment, tools, materials and the prepared arc-shaped brackets are transported to the vicinity of the location where the vertical upward jacking construction of the existing underground tunnel is planned to be carried out, and water and electricity are connected to the vicinity of the location; S2. Construction cushion: In the existing tunnel arch bottom section where vertical jacking construction is to be carried out, a release agent is applied, steel bars are tied and concrete is poured to form a reinforced concrete cushion; S3. Tunnel vault grouting: Based on the grouting holes and hoisting holes of the pipe segments, grouting is performed around the vault of the existing tunnel where vertical jacking construction is to be carried out along the center line of the pipe segment to be jacked in to form a grouting body. The grouting material is cement slurry. The grouting range is not less than 1.5 times the diameter of the pipe segment to be jacked in, and the length of the grouting pipe is not less than 1.0m; S4. Bury plastic pipes through holes on the ground: Drill holes on the ground along the center line of the pipe section to be inserted until the distance from the tunnel arch is no more than 2.0m. After drilling and cleaning the holes, insert the plastic pipes into the holes, fill the inside of the plastic pipes with medium-coarse sand, and evenly set water outlet holes around the plastic pipes; S5. Assemble the arc bracket: Based on the bottom crossbeam and the top crossbeam, assemble the two processed arc brackets on the cushion layer in the tunnel below the center line of the proposed jacking pipe segment; S6. Breaking the tunnel vault and jacking construction position: Break the existing tunnel structure around the tunnel vault along the center line of the pipe section to be jacked to form a hole, so that the range of the hole is larger than the outer contour diameter of the pipe section; S7. Install the jacking fixture: install the jacking fixture on the top of the assembled arc bracket, so that the center line of the steel ring plate on the jacking fixture coincides with the center line of the pipe segment to be jacked, support the formwork around the jacking fixture, and inject cement slurry into the jacking fixture through the grouting holes, so that the gap between the jacking fixture and the tunnel vault is densely filled with grouting without water seepage; S8. Install the pipe jacking machine: With the help of the clamping device and the vertical jack installed on the arc support, fix the pipe jacking machine and the pipe segment inside the arc support in the vertical direction. The center line of the pipe jacking machine and the pipe segment coincides with the center line of the designed pipeline. The head of the pipe jacking machine passes through the steel ring plate of the fixed frame and contacts with the upper soil. S9. Soil injection and softening: Before the jacking construction begins, water is injected into the plastic pipe to pre-soften the soil cut in front of the pipe jacking machine during the vertical jacking construction, so that the soil can be loosened and the soil can be loosened to ensure the smooth advancement of the jacking pipe; S10. Pipe segment jacking operation: Under the jacking force of the vertical jack and the cutting action of the pipe jacking machine, the pipe segment is gradually jacked upward. During the jacking process, the clamping device installed on the arc bracket is used to constrain and fix the jacked pipe segment, and the pipe segments are inserted and connected in sequence below, so that each pipe segment is connected and lengthened one by one and pushed vertically upward into the soil; S11. Cutting the surface soil: When the head of the pipe jacking machine is 2.0m to 3.0m away from the surface, use the equipment to cut the soil on the surface along the center line of the pipe segment to form a soil cutting surface. The depth of the soil cutting surface shall not be less than 1.5m, and the distance between the soil cutting surface and the center line of the pipe segment shall be greater than the radius of the pipe segment by 20cm to 30cm; S12. Continue the jacking operation mentioned in step S10 until the pipe jacking machine is pushed out of the ground surface, dismantle the pipe jacking machine and various components, clean the working surface, and complete the vertical upward pipe jacking construction.

2. The vertical upward pipe jacking construction method in a hard plastic clay layer as claimed in claim 1, characterized in that: When the soil is softened by water injection in step S9, the water injection amount and the pre-injection time should be controlled according to the soil permeability coefficient, so that the soil being cut directly above the pipe jacking machine is soaked with water when the pipe jacking machine is jacking vertically upward. When the jacking operation stops, the water injection should also be stopped.

3. The vertical upward pipe jacking construction method in a hard plastic clay layer as claimed in claim 1, characterized in that: The pipe jacking machine adopts a segmented advancement method during the jacking operation. After advancing a certain distance, it pauses in stages, then checks the soil conditions and makes appropriate adjustments to the pipe jacking machine to ensure that the thrust and advancement speed are always within an appropriate range, thereby reducing the impact on the equipment and soil layer and ensuring construction quality and safety.

4. The vertical upward pipe jacking construction method in a hard plastic clay layer as claimed in claim 1, characterized in that: Under the cutting action of the pipe jacking machine, the hard plastic clay layer is cut into granules or mud, which is convenient for slag discharge. The slag discharge is to mix the soil and water into mud through a pipe, pump it to the ground through a mud pump, and then discharge or backfill it after purification, so that it can effectively avoid earth backlog and settlement problems.

5. The vertical upward pipe jacking construction method in a hard plastic clay layer as claimed in claim 1, characterized in that: After completing the vertical upward pipe jacking construction in step S12, the pipeline needs to be inspected for quality to ensure the integrity and stability of the pipeline. The inspection content includes but is not limited to the joints, wall thickness and sealing of the pipeline. At the same time, combined with the particularity of the hard plastic clay layer, it is necessary to monitor the settlement of the soil layer around the pipeline to prevent impact on surrounding buildings or infrastructure.

6. The vertical upward pipe jacking construction method in a hard plastic clay layer as claimed in claim 1, characterized in that: The arc-shaped bracket is welded by a bottom longitudinal beam, an arc-shaped column and a top longitudinal beam, and two arc-shaped brackets are connected and fixed by a bottom cross beam, a top cross beam and bolts with pre-arranged bolt holes that match each other.

7. The vertical upward pipe jacking construction method in a hard plastic clay layer as claimed in claim 1, characterized in that: The middle and upper part of the arc-shaped bracket is welded and assembled by a hanger, a supporting beam, a supporting plate and a reaction plate to form a matching mechanism with the clamping device. Slots are provided on both sides of the supporting plate. The reaction plate is welded between two arc-shaped columns. The clamping device can move along the supporting plate under the action of a horizontal jack.

8. The vertical upward pipe jacking construction method in a hard plastic clay layer as claimed in claim 7, characterized in that: The clamping device is welded by a bottom plate, a top force plate, a vertical plate and an arc plate. The inner diameter of the arc plate is equal to the outer diameter of the pipe segment. The width and height of the bottom plate are slightly smaller than the net width and net height between the slots on both sides of the support plate. After the bottom plate is inserted between the slots on both sides of the support plate, it can slide relative to the support plate without detaching.

9. The vertical upward pipe jacking construction method in a hard plastic clay layer as claimed in claim 7, characterized in that: After the bottom plate in the clamping device is inserted between the two side slots on the support plate, the clamping device can slide relatively along the support plate under the action of the horizontal jack, and the bottom of the horizontal jack acts on the reaction plate, so that the top of the horizontal jack acts on the top force plate of the clamping device.

10. The vertical upward pipe jacking construction method in a hard plastic clay layer as claimed in claim 1, characterized in that: The jacking fixing frame is welded by a horizontal enclosure, a vertical enclosure and a steel ring plate. The inner diameter of the steel ring plate is 3.0 cm to 10.0 cm larger than the outer diameter of the pipe segment. No less than 4 grouting holes are evenly arranged on the horizontal enclosure, and no less than 4 bolt holes are symmetrically arranged on the outer side of the vertical enclosure. The bolt holes can be connected to each other based on bolts and matching bolt holes on the top longitudinal beam.

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