Structure and construction method to prevent late settlement of pipe jacking pipeline in soft soil foundation

Abstract

The present invention discloses a structure and construction method for preventing late settlement of a pipe jacking pipe on a soft soil foundation, and relates to the technical field of pipe jacking engineering. A tension device is arranged at intervals on the pipe between two inspection wells of the pipe jacking construction, and the tension device is mainly composed of a tension pipe 1, a tension pile 2, a pull rod 3, and a tension platform 4. The tension pile 2 and the tension platform 4 are cast with reinforced concrete. The tension pipe 1 is provided with an anchor hole 5, and the lower part of the pull rod 3 is provided with an anchor head 6, which is embedded in the anchor hole 5. By utilizing the bearing capacity of the good soil on the upper part of the pipeline, by expanding the bearing capacity of the tension platform 4 on the bottom and the friction force of the tension pile 2, the pipeline is pulled by the pull rod 3, the pressure of the pipeline's own weight on the soft soil foundation is overcome, and the settlement of the pipe jacking pipeline at the soft soil foundation is prevented. From the perspective of the force on the pipeline, the late settlement problem of the pipe jacking pipeline is effectively solved, and the construction is simple and the quality is controllable.

Description

Technical Field

[0001] The invention relates to the technical field of pipe jacking engineering, and in particular to a structure and a construction method for preventing late settlement of a pipe jacking pipeline on a soft soil foundation. Background Art

[0002] Pipe jacking is a trenchless construction method with the advantages of fast construction speed and little impact on the ground. It is increasingly widely used in urban pipeline construction with heavy traffic, dense population, numerous ground buildings, and complex underground structures and pipelines. With the development of cities, the hardening of the ground has caused an increase in the flow of water. The original drainage system cannot meet the discharge requirements, and low-lying areas are prone to waterlogging. Many urban built-up areas use pipe jacking construction when renovating the drainage system, replacing the original rainwater pipes with smaller diameters with pipes with larger diameters. However, if the downstream pipes are not renovated at the same time, they cannot accommodate excessive rainwater. The expansion of rainwater pipes combined with the setting of storage tanks to collect rainwater for peak-shifting storage can reduce the pressure on downstream rainwater pipes. The remaining rainwater can be used for sprinkling roads and green irrigation, which solves the problem that the downstream pipes cannot accommodate rainstorms, and can also make comprehensive use of rainwater to save water resources.

[0003] The pipes used in the existing technology of pipe jacking construction are generally grade III reinforced concrete pipes, steel sleeve socket joints, rubber ring seals are set inside the joints, and there is a gap of 5~10mm between the outer diameter of the socket and the inner diameter of the socket, which is convenient for insertion when the pipe is connected. During the pipe jacking construction, the direction of the pipeline deviates. The correction system uses the gap at the pipe interface to produce a slight deflection, and automatically corrects the deviation to make the pipeline jack along the designed direction and elevation within the allowable error. Soft soil foundations mainly include silt, silty soil, liquefied sand layers, etc., which are common in the Pearl River Delta, Yangtze River Delta and coastal areas. The jacking speed is fast during the jacking construction of soft soil foundations, but due to the low bearing capacity of the foundation, the jacking construction cannot reinforce the foundation. After the jacking construction is completed, the dead weight of the pipeline will cause a large settlement in the later stage. The actual measurement of a project shows that the maximum settlement in the middle of the jacking pipeline with a diameter of 1800mm, which has been completed for about 10 years, is 150m apart from the two inspection wells, and is about 870mm. The deflection at each pipe interface caused by settlement is very small, and the cumulative deflection of multiple pipe sections will form a large settlement. The pipe interface is sealed with a rubber ring. Although there will be no water leakage, the settlement of the pipe causes mud and sand to accumulate at the bottom of the pipe, and the effective cross-section of the pipe is reduced. In order to solve this problem, the prior art has a method of lengthening the length of the steel sleeve socket, reducing the interface gap, and reducing the deflection angle between the pipe interfaces; there is a method of setting a bolt locking interface at the steel sleeve interface to prevent the pipe interface from deflecting. However, these methods do not solve the problem from the perspective of pipeline force, and cannot effectively solve the problem of pipeline settlement. The prior art also has grouting around the jacking pipe to reinforce the soft soil foundation, but the effect of injecting the slurry into the soft soil foundation is not controlled, and the effect is very limited when encountering a silty soft soil foundation with a high water content. Summary of the invention

[0004] The purpose of the present invention is to provide a structure for preventing the late settlement of a jacking pipe on a soft soil foundation. A tension device is arranged at intervals on the pipe between two inspection wells of the jacking pipe construction. The tension device includes main tension piles, a tension rod, and a tension platform. The platform bearing capacity of the bottom surface is expanded, the peripheral friction force of the tension piles is used, and the tension rod is anchored to the pipe, so that the pipe is pulled to reduce the pressure on the base, thereby preventing the jacking pipe from settling on the soft soil foundation.

[0005] The present invention is realized by the following technologies: a structure for preventing the late settlement of the jacking pipe on the soft soil foundation, a tension device is arranged at intervals on the jacking pipe 200 between the inspection wells 100, and the tension device is mainly composed of a tension pipe 1, a tension pile 2, a tie rod 3, and a tension platform 4. The tension pipe 1 is provided with an anchor hole 5, and the lower part of the tie rod 3 is provided with an anchor head 6, and the anchor head 6 is embedded in the anchor hole 5. The tie rod 3 is located in the middle of the tension pile 2, and the tension pile 2 is cast with reinforced concrete. The tension platform 4 is buried under the ground, and the tension pile 2 and the tie rod 3 extend into the tension platform 4 and are anchored together. The bearing capacity of the bottom surface of the tension platform 4 outside the tension pile 2 supported on the foundation and the friction force of the soil around the tension pile 2 work together, and the tension pipe 1 is pulled by the tie rod 3 to prevent the jacking pipe from settling in the soft soil foundation.

[0006] The anchor hole 5 is arranged at the top end of the middle part of the tension pipe 1 , and a steel ring 7 is arranged in the pipe wall corresponding to the anchor hole 5 , and the steel ring 7 surrounds the pipe wall and is fixed to the anchor hole 5 .

[0007] The top plate of the anchor hole 5 is provided with a flared hole 8 and an anchor groove 9, and the surface is covered with a protective film, on which the positions of the flared hole 8 and the anchor groove 9 are marked. The end of the anchor head 6 is a truncated cone 10, and the edge of the anchor hole 5 corresponding to the flared hole 8 is provided with a slope surface 11. The anchor head 6 of the pull rod 3 is inserted into the flared hole 8, and under the guidance of the slope surface 11, the anchor head 6 is embedded in the anchor groove 9 of the anchor hole 5.

[0008] The tension pile 2 has a diameter of 300-500 mm and is provided with a tension pile reinforcement 12 .

[0009] The tension rod 3 is provided with a resistance-increasing tenon 13 , which is anchored in the concrete of the tension pile 2 .

[0010] The tension-bearing platform 4 is provided with tension-bearing platform steel bars 14, and the tension-bearing pile steel bars 12 extend into the tension-bearing platform 4 and are anchored with the tension-bearing platform steel bars 14. An anchor steel plate 15 is provided in the tension-bearing platform 4 and is supported on the top of the tension-bearing pile steel bars 12. An installation hole is provided in the center of the anchor steel plate 15 for connecting the pull rod 3.

[0011] The pull rod 3 passes through the mounting hole of the anchor steel plate 15 and is tightened and fixed by a locking nut 16 .

[0012] The tensioning devices are arranged at intervals of 5 to 20 m.

[0013] The construction method of the present application for preventing the late settlement of the pipe jacking pipeline on the soft soil foundation comprises the following steps:

[0014] a. During pipe jacking construction, the tension pipe 1 is pushed in according to the designed spacing, and the tension pipe 1 is connected to the ordinary pipe through the interface;

[0015] b. Accurately mark the position of the tension pile 2 on the ground along the jacking pipeline, and excavate the foundation pit of the tension platform 4 with the tension pile 2 as the center;

[0016] c. Drill holes at the position of the foundation pit corresponding to the tension pile 2 using an auger, and stop drilling when the drilling depth is close to the top of the tension pipe 1;

[0017] d. Use a high-pressure water gun to flush the top of the tension pipe 1, and then pump out the water in the pile hole;

[0018] e. After the remaining accumulated water seeps into the ground and the anchor hole 5 is exposed, the anchor head 6 of the pull rod 3 is aligned with the mark of the expanded hole 8 on the protective film and inserted into the expanded hole 8. Under the guidance of the slope surface 11, the truncated cone 10 of the anchor head 6 moves along the slope surface 11 toward the anchor groove 9, and the anchor head 6 is moved to the anchor hole 5 and embedded in the anchor groove 9;

[0019] f. Install the tension pile reinforcement 12 in the pile hole of the tension pile 2;

[0020] g. Install the tension platform steel bars 14 in the foundation pit of the tension platform 4, and weld the tension pile steel bars 12 to the tension platform steel bars 14;

[0021] h. Sleeve the hole of the anchoring steel plate 15 on the tie rod 3, install the anchoring steel plate 15 on the top of the tension pile reinforcement 12 and weld it firmly, and use the locking nut 16 to fix the tie rod 3 on the anchoring steel plate 15;

[0022] i. pouring concrete of the tension pile 2 and compacting it with a vibrating rod;

[0023] j. Pour the concrete of the tensile platform 4 and compact it with a vibrating rod;

[0024] k. When the concrete strength of the tension piles 2 and the tension platform 4 reaches 70% of the design strength, backfill the foundation pit of the tension platform 4 and restore the ground according to the original structure.

[0025] The beneficial effects of the present invention are as follows: utilizing the bearing capacity of the good soil above the pipeline, by expanding the bearing capacity of the bottom platform and the friction of the pile body, the pipeline is pulled to overcome the pressure of its own weight on the soft soil foundation, and the later settlement problem of the jacking pipeline is effectively solved from the perspective of pipeline force, with simple construction and controllable quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a longitudinal section view of the present invention;

[0027] Figure 2 It is a longitudinal section view of the connection between the tension pile and the tension pipe;

[0028] Figure 3 It is a cross-sectional view of the connection between the tension pile and the tension pipe;

[0029] Figure 4 This is the side view of the anchor hole;

[0030] Figure 5 This is the top view of the anchor hole;

[0031] Figure 6 Structural diagram of the connection between the tension platform and the tension piles.

[0032] In the figure: 1-tension-bearing pipe, 2-tension-bearing pile, 3-tension rod, 4-tension-bearing platform, 5-anchor hole, 6-anchor head, 7-steel ring, 8-expanded hole, 9-anchor groove, 10-conical head, 11-slope surface, 12-tension-bearing pile steel bar, 13-resistance-increasing tenon, 14-tension-bearing platform steel bar, 15-anchor steel plate, 16-locking nut, 100-inspection well, 200-jacking pipe. DETAILED DESCRIPTION

[0033] In order for those skilled in the art to better understand the present invention, Figure 1 to Figure 5 To further explain the present application, in the present description, the terms "upper", "lower", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or directions or positional relationships commonly understood by those skilled in the art. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the components or parts referred to must have a specific direction, be constructed and operated in a specific direction. The contents mentioned in the implementation manner are not limitations of the present invention.

[0034] The structure of the present invention for preventing the late settlement of the jacking pipe on the soft soil foundation is that after the jacking construction is completed, a pulling device is installed on the pipe, and the pulling device is arranged on the jacking pipe 200 between the inspection wells 100. Figure 1The dotted line part of the drawing is the trend of pipeline settlement. The spacing of the tension device is determined according to the geological conditions, the deadweight of the pipeline and the thickness of the soil covering the top of the pipe. Generally, one is set at an interval of 5 to 20 meters. The tension device is mainly composed of tension pipe 1, tension pile 2, tension rod 3 and tension platform 4.

[0035] The tension pipe 1 is the same as the pipe used for jacking, except that an anchoring device is added. The tension pipe 1 is provided with an anchor hole 5 for connecting with the pulling device on the upper part. The anchor hole 5 is set at the top of the middle part of the tension pipe 1, and a steel ring 7 is set in the wall of the corresponding anchor hole 5. The steel ring 7 surrounds the wall of the pipe and is fixed to the anchor hole 5 to enhance the pulling strength of the tension pipe 1. Figure 2 , Figure 3 . The steel ring 7 is made of a steel plate with a thickness of 10~20mm and a width of 200~300mm. The upper part is welded to the anchor hole 5. The anchor hole 5 and the steel ring 7 are embedded in the pipe when the tension pipe 1 is prefabricated. The anchor hole 5 is made of a steel plate with a thickness of 10~20mm. The top plate of the anchor hole 5 is provided with a flared hole 8 and an anchor groove 9. The surface of the anchor hole 5 is covered with a protective film to prevent soil from entering the flared hole 8 and the anchor groove 9 during the jacking construction. The positions of the flared hole 8 and the anchor groove 9 are marked on the protective film. An anchor head 6 is provided at the lower part of the pull rod 3. The end of the anchor head 6 is a frustum 10. The edge of the anchor hole 5 corresponding to the flared hole 8 is provided with a slope surface 11. The anchor head 6 of the pull rod 3 is inserted into the flared hole 8. Under the guidance of the slope surface 11, the anchor head 6 is embedded in the anchor groove 9 of the anchor hole 5. Figure 4 , Figure 5 .

[0036] The tie rod 3 is made of high-strength steel bars with a diameter of 25~32mm. The lower part of the tie rod 3 is welded with an anchor head 6, and the upper part is provided with a thread, which cooperates with a locking nut 16 to anchor the tie rod 3 to the tension platform 4. The tie rod 3 is located in the middle of the tension pile 2. The tension pile 2 is cast with reinforced concrete, and the concrete strength is preferably C30. The tie rod 3 is provided with a resistance-enhancing tenon 13, which is welded on the tie rod 3 and anchored in the concrete of the tension pile 2 to enhance the pull-out resistance of the tie rod 3. The tension pile 2 has a diameter of 300~500mm, and the tension pile 2 is provided with a tension pile reinforcement 12, see Figure 2 , Figure 3 .

[0037] The tension-bearing platform 4 is buried under the ground with a depth of 0.8~1.0m. The thickness of the tension-bearing platform 4 is 200~300mm, and the shape is a square or rectangle with a side length of 2~3m. The tension-bearing platform 4 is provided with tension-bearing platform steel bars 14, and the tension-bearing pile steel bars 12 extend into the tension-bearing platform 4 and are anchored with the tension-bearing platform steel bars 14. An anchoring steel plate 15 is provided in the tension-bearing platform 4, supported on the top of the tension-bearing pile steel bars 12, and the anchoring steel plate 15 is made of a steel plate with a thickness of 10~20mm. A mounting hole is provided in the center of the anchoring steel plate 15 for connecting the tie rod 3. The tie rod 3 passes through the mounting hole of the anchoring steel plate 15 and is tightened and fixed with a locking nut 16, see Figure 6 The tension platform 4 is cast with C30 concrete.

[0038] The tension piles 2 and the tie rods 3 extend into the tension platform 4 and are anchored together. The bearing capacity of the bottom surface of the tension platform 4 outside the tension piles 2 supported on the foundation and the friction force of the soil around the tension piles 2 work together to pull the tension pipe 1 through the tie rods 3 to prevent the jacking pipeline from settling in the soft soil foundation.

[0039] The construction method of the present invention for preventing the late settlement of the jacking pipe on the soft soil foundation shall detect the underground pipelines and cables along the pipeline before the jacking construction, and the tension device shall avoid the underground pipelines and cables. If the anchor hole 5 of the tension pipe 1 is just under the transverse pipeline according to the designed spacing, one section of the pipe can be adjusted to avoid it during the jacking construction, and the length of the jacking pipe is generally 2m per section. For example: the designed spacing of the tension pipe 1 is 10m, and the anchor hole 5 is just under the underground pipeline, which affects the construction of the tension pile 2. The position of one section of the tension pipe 1 can be adjusted during the jacking, with a spacing of 8m on one side and 12m on the other side.

[0040] The specific construction steps are as follows:

[0041] a. During pipe jacking construction, the tension pipe 1 is pushed in according to the designed spacing, and the tension pipe 1 is connected to the ordinary pipe through the interface;

[0042] b. Use a total station or theodolite plus a steel ruler to accurately mark the position of the tension pile 2 on the ground along the jacking pipeline, and excavate the foundation pit of the tension platform 4 with the tension pile 2 as the center, with a foundation pit depth of 0.8~1.0m;

[0043] c. Drill holes at the position of the foundation pit corresponding to the tension pile 2 using an auger, and stop drilling when the drilling depth is close to the top of the tension pipe 1;

[0044] d. Use a high-pressure water gun to wash the top of the tension pipe 1, and then pump out the water in the pile hole. It is advisable to use a sewage suction truck to pump out the water and mud together;

[0045] e. After the remaining accumulated water seeps into the ground and exposes the anchor hole 5, align the anchor head 6 of the pull rod 3 with the mark of the expanded hole 8 on the protective film and insert it into the expanded hole 8. Under the guidance of the slope surface 11, the frustum 10 of the anchor head 6 moves along the slope surface 11 toward the anchor groove 9, and the anchor head 6 is moved to the anchor hole 5 manually and embedded in the anchor groove 9.

[0046] f. Install the tension pile reinforcement 12 in the pile hole of the tension pile 2;

[0047] g. Install the tension platform steel bars 14 in the foundation pit of the tension platform 4, and weld the tension pile steel bars 12 to the tension platform steel bars 14;

[0048] h. Sleeve the hole of the anchoring steel plate 15 on the tie rod 3, install the anchoring steel plate 15 on the top of the tension pile reinforcement 12 and weld it firmly, and use the locking nut 16 to fix the tie rod 3 on the anchoring steel plate 15;

[0049] i. pouring concrete of the tension pile 2 and compacting it with a vibrating rod;

[0050] j. Pour the concrete of the tensile platform 4 and compact it with a vibrating rod;

[0051] k. When the concrete strength of the tension piles 2 and the tension platform 4 reaches 70% of the design strength, backfill the foundation pit of the tension platform 4 and restore the ground according to the original structure.

[0052] The structure described in the application document and the drawings of the present invention is only an embodiment. Structures in which the upper part of the pipeline is pulled and placed under the pipeline are all within the protection scope of the present application.

Claims

1. A structure for preventing late settlement of a pipe jacking pipeline on a soft soil foundation, characterized in that: A tension device is provided at intervals on the top pipe (200) between the inspection wells (100), and the tension device is mainly composed of a tension pipe (1), a tension pile (2), a tension rod (3), and a tension platform (4). The tension pipe (1) is provided with an anchor hole (5), and the lower part of the tension rod (3) is provided with an anchor head (6), and the anchor head (6) is embedded in the anchor hole (5). The anchor hole (5) is arranged at the top end of the middle part of the tension pipe (1), and a steel ring (7) is provided in the pipe wall corresponding to the anchor hole (5). The steel ring (7) surrounds the pipe wall and is fixed to the anchor hole (5). The top plate of the anchor hole (5) is provided with a flared hole (8) and an anchor groove (9), and the surface is covered with a protective film, and the positions of the flared hole (8) and the anchor groove (9) are marked on the protective film. The end of the anchor head (6) is A conical head (10), an edge of the anchor hole (5) corresponding to the flared hole (8) is provided with a slope surface (11), the anchor head (6) of the tie rod (3) is inserted into the flared hole (8), and under the guidance of the slope surface (11), the anchor head (6) is embedded in the anchor groove (9) of the anchor hole (5); the tie rod (3) is located in the middle of the tension pile (2), the tension pile (2) is cast with reinforced concrete, the tension platform (4) is buried under the ground, the tension pile (2) and the tie rod (3) extend into the tension platform (4) and are anchored together, the bearing capacity of the bottom surface of the tension platform (4) outside the tension pile (2) supported on the foundation and the friction force of the soil around the tension pile (2) work together, and the tension pipe (1) is pulled by the tie rod (3) to prevent the jacking pipe from settling in the soft soil foundation.

2. The structure for preventing late settlement of pipe jacking pipelines on soft soil foundation according to claim 1 is characterized by: The tension pile (2) has a diameter of 300-500 mm, and the tension pile (2) is provided with tension pile reinforcement bars (12).

3. The structure for preventing late settlement of pipe jacking pipelines on soft soil foundation according to claim 1 is characterized by: The tension rod (3) is provided with a resistance-increasing tenon (13) and is anchored in the concrete of the tension pile (2).

4. The structure for preventing late settlement of pipe jacking pipelines on soft soil foundation according to claim 1 is characterized by: The tension-bearing platform (4) is provided with tension-bearing platform steel bars (14), the tension-bearing pile steel bars (12) extend into the tension-bearing platform (4) and are anchored to the tension-bearing platform steel bars (14), an anchoring steel plate (15) is provided inside the tension-bearing platform (4) and is supported on the top of the tension-bearing pile steel bars (12), and a mounting hole is provided at the center of the anchoring steel plate (15) for connecting the tension rod (3).

5. The structure for preventing late settlement of pipe jacking pipelines on soft soil foundation according to claim 4 is characterized in that: The pull rod (3) passes through the mounting hole of the anchoring steel plate (15) and is tightened and fixed by a locking nut (16).

6. The structure for preventing late settlement of pipe jacking pipelines on soft soil foundation according to claim 1 is characterized by: The tensioning devices are arranged at intervals of 5 to 20 m.

7. A construction method for preventing late settlement of pipe jacking pipelines on soft soil foundation according to claim 1, characterized in that: The construction method comprises the following steps: a. During pipe jacking construction, the tension pipe (1) is pushed in according to the designed spacing, and the tension pipe (1) is connected to the ordinary pipe through an interface; b. Accurately mark the position of the tension piles (2) on the ground along the jacking pipeline, and excavate the foundation pit of the tension platform (4) with the tension piles (2) as the center; c. Drilling holes at positions corresponding to the tension piles (2) in the foundation pit using a spiral drill, and stopping drilling when the drilling depth is close to the top of the tension pipe (1); d. Use a high-pressure water gun to flush the top of the tension pipe (1), and then pump out the water in the pile hole; e. After the remaining accumulated water seeps into the ground and exposes the anchor hole (5), the anchor head (6) of the pull rod (3) is aligned with the mark of the expanded hole (8) on the protective film and inserted into the expanded hole (8). Under the guidance of the slope surface (11), the conical head (10) of the anchor head (6) moves along the slope surface (11) toward the anchor groove (9), and the anchor head (6) is moved to the anchor hole (5) and embedded in the anchor groove (9); f. Installing the tension pile reinforcement (12) in the pile hole of the tension pile (2); g. Install the tension platform steel bars (14) in the foundation pit of the tension platform (4), and weld the tension pile steel bars (12) to the tension platform steel bars (14); h. Sleeve the hole of the anchoring steel plate (15) onto the tension rod (3), install the anchoring steel plate (15) on the top of the tension pile reinforcement (12) and weld it firmly, and use a locking nut (16) to fix the tension rod (3) on the anchoring steel plate (15); i. pouring concrete for the tension pile (2) and compacting it using a vibrating rod; j. Pour the concrete of the tension platform (4) and compact it using a vibrator; k. When the concrete strength of the tension piles (2) and the tension platform (4) reaches 70% of the design strength, the foundation pit of the tension platform (4) is backfilled and the ground is restored to its original structure.

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