Structure for improving water stop performance at joint of underground diaphragm wall and cast-in-situ bored pile

Abstract

The utility model discloses a structure for improving the water stop performance of a joint of an underground diaphragm wall and a cast-in-situ bored pile. The structure comprises an underground diaphragm wall and a cast-in-situ bored pile which are adjacent to each other, a diaphragm wall reinforcement cage is arranged in the underground diaphragm wall, and embedded grouting pipes which are arranged at intervals are connected to the positions, close to the cast-in-situ bored pile, of the outer side of the diaphragm wall reinforcement cage; a cast-in-place pile reinforcement cage is arranged in the cast-in-place pile, and embedded grouting pipes which are vertically arranged at intervals are connected to the position, close to the underground diaphragm wall, of the outer side of the cast-in-place pile reinforcement cage; the inner space and the outer space of the continuous wall reinforcement cage are filled with concrete, the inner space and the outer space of the cast-in-place pile reinforcement cage are filled with concrete, a plurality of grouting holes are formed in the pipe wall of the pre-buried grouting pipe at intervals, and cement grout is injected into the pre-buried grouting pipe. The water stop performance of the joint of the underground diaphragm wall and the cast-in-situ bored pile is improved, the number of high-pressure jet grouting piles arranged at the joint of the underground diaphragm wall and the cast-in-situ bored pile is reduced, and the trouble of insufficient operation space is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of foundation pit engineering, in particular to a structure for improving the water stopping performance of the joint between an underground continuous wall and a bored cast-in-place pile. Background Art

[0002] Foundation pit support is a temporary measure of support, reinforcement, protection and groundwater control for the foundation pit to protect the safety of the underground main structure construction and the surrounding environment of the foundation pit. Whether to use a support structure for foundation pit excavation and what kind of support structure to use should be determined through comprehensive economic, technical and environmental analysis and comparison based on the surrounding environment of the foundation pit, the excavation depth of the foundation pit, engineering geological and hydrogeological conditions, construction conditions, construction season, regional engineering experience, etc. In foundation pit projects with high groundwater levels, poor stratum conditions and large excavation depths, support structures such as bored cast-in-place piles, underground continuous walls, and interlocking cast-in-place piles are often used.

[0003] Bored piles are bored on the ground by rotary drilling equipment under the condition of mud wall protection. After the trench is cleared, the steel cage is lowered and underwater concrete is poured using the conduit method to form a bored pile. The gaps between the bored piles are often filled by high-pressure rotary jet piles, three-axis mixing piles, MJS, TRD or CSM and other processes to improve the original soil into cement-reinforced soil with certain strength and anti-penetration properties, thereby achieving the purpose of resisting the water and soil pressure outside the foundation pit and ensuring the safety of foundation pit excavation.

[0004] The underground continuous wall is built by digging a long and narrow deep trench on the ground under the condition of mud wall protection. After the trench is cleared, the steel cage is lowered and underwater concrete is poured using the conduit method to form a unit trench section. This process is carried out section by section to build a continuous reinforced concrete wall underground.

[0005] In actual engineering applications, bored cast-in-place piles and underground continuous walls are suitable for different scenarios and have various characteristics. For example, the supporting structure of the underground continuous wall has the characteristics of high rigidity, good water-stopping performance and high cost, and is often used in foundation pit projects with large excavation depths. The supporting structure of bored cast-in-place piles + high-pressure rotary jet piles has the characteristics of moderate rigidity, good water-stopping performance and moderate cost, and is often used in foundation pit projects with large excavation depths. In actual application, in the process of the excavation depth of the foundation pit changing from deep to shallow, it is often necessary to arrange two retaining structures, the underground continuous wall and the bored cast-in-place piles, at the same time. Due to the certain difference in the rigidity of the underground continuous wall and the bored cast-in-place piles, the deformation is inconsistent during the foundation pit excavation process, and water seepage and soil leakage are prone to occur at the junction of the two. In order to solve this problem, multiple high-pressure rotary jet piles are often added at the joints of the underground continuous wall and the bored cast-in-place piles to increase the range of soil reinforcement at the joints, such as Figure 1As shown (1 represents underground continuous wall, 2 represents bored cast-in-place piles, 3 represents high-pressure rotary jet piles, and multiple high-pressure rotary jet piles are arranged at the joints between the underground continuous wall and the bored cast-in-place piles), its principle and specific method are similar to those of bored cast-in-place piles + high-pressure rotary jet piles.

[0006] However, in the actual application of the method of adding high-pressure rotary jet piles at the joints of underground continuous walls and bored cast-in-place piles, there are the following difficulties: when there are underground pipelines around the foundation pit, there is a problem of insufficient operating space for the arrangement of multiple high-pressure rotary jet piles. Summary of the invention

[0007] In view of the shortcomings of the prior art, the utility model proposes a structure for improving the water-stopping performance at the joints between underground continuous walls and bored cast-in-place piles, thereby improving the water-stopping performance at the joints between underground continuous walls and bored cast-in-place piles, reducing the number of high-pressure rotary jet piles arranged at the joints between the two, and avoiding the problem of insufficient operating space.

[0008] In order to achieve the above-mentioned purpose, the utility model is designed to improve the water-stopping performance of the joint between the underground continuous wall and the bored pile, including the adjacent underground continuous wall and the bored pile, and its special features are:

[0009] A continuous wall steel cage is arranged inside the underground continuous wall, and a plurality of pre-buried grouting pipes arranged at intervals and vertically are connected to the outer side of the continuous wall steel cage near the location of the bored piles;

[0010] A cast-in-place pile reinforcement cage is arranged inside the bored cast-in-place pile, and a plurality of pre-buried grouting pipes arranged vertically and spaced apart are connected to the outer side of the cast-in-place pile reinforcement cage near the underground continuous wall;

[0011] The inner and outer spaces of the continuous wall steel cage are filled with concrete, the inner and outer spaces of the cast-in-place pile steel cage are filled with concrete, a plurality of grouting holes arranged at intervals are drilled in the wall of the pre-buried grouting pipe, and cement slurry is injected into the pre-buried grouting pipe;

[0012] The underground continuous wall and bored cast-in-place piles are fixed with a number of water-stop steel plates arranged in sequence from top to bottom corresponding to the inner side surfaces of the excavated foundation pit, and the gaps enclosed between each of the water-stop steel plates and the underground continuous wall and bored cast-in-place piles are filled with cement slurry.

[0013] Furthermore, the allowable deviation of the length of the underground continuous wall and bored piles is ±1.0-3.0%, the allowable deviation of the thickness is ±8-12 mm, the allowable deviation of the verticality is ±1 / 320-1 / 280, and the local protrusion of the surface is less than or equal to 100 mm.

[0014] Furthermore, the grouting holes are arranged in a plum blossom shape, with a hole diameter of 8 to 12 mm and a hole spacing of 20 to 30 cm.

[0015] Furthermore, the upper and lower ends of the wall of the pre-buried grouting pipe are respectively grouting-stopping sections without drilling holes, and a plurality of grouting holes are arranged in the middle section of the wall of the pre-buried grouting pipe.

[0016] Furthermore, a plurality of pre-buried grouting pipes outside the cast-in-place pile reinforcement cage are distributed at intervals in an arc shape.

[0017] Furthermore, the bottom end of the pre-buried grouting pipe extends to the bottom of the underground continuous wall and the bottom of the bored pile hole respectively.

[0018] Furthermore, the pre-buried grouting pipe is tied and connected to the continuous wall reinforcement cage and the cast-in-place pile reinforcement cage respectively.

[0019] Furthermore, each of the water-stopping steel plates is fixedly connected to the underground continuous wall and the bored cast-in-place piles through expansion bolts.

[0020] The advantages of the utility model are:

[0021] 1. The utility model arranges vertically spaced pre-buried grouting pipes on the outer side of the continuous wall steel cage near the position of the bored piles, and ties the pre-buried grouting pipes to the continuous wall steel cage; arranges vertically spaced pre-buried grouting pipes on the outer side of the bored pile steel cage near the position of the underground continuous wall, and ties the pre-buried grouting pipes to the bored pile steel cage; constructs the underground continuous wall first, and then constructs the bored piles. After the underground continuous wall and the bored piles reach the design strength and before the foundation pit excavation construction, the pre-buried grouting pipes are reinforced with cement grouting, so as to achieve the purpose of improving the water-stopping performance of the joints and ensure the safety of the foundation pit excavation construction;

[0022] 2. During the excavation of the foundation pit, the utility model installs water-stop steel plates one by one from top to bottom on the inner side of the underground continuous wall and bored piles corresponding to the excavated foundation pit, and fills the gaps between the water-stop steel plates and the underground continuous wall and bored piles with cement slurry, which not only ensures the safety of excavation, but also improves the water-stop performance of the joints between the underground continuous wall and the bored piles;

[0023] The utility model discloses to improve the structure of the water-stopping performance at the joint of the underground continuous wall and the bored cast-in-place pile, improve the water-stopping performance at the joint of the underground continuous wall and the bored cast-in-place pile, enhance the shear strength at the joint position, reduce the number of high-pressure rotary jet piles arranged at the joint of the two, and avoid the trouble of insufficient operating space. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a plan layout diagram of underground continuous wall and bored piles in the prior art;

[0025] Figure 2 A plan view of the structure for improving the water-stopping performance at the joint between the underground continuous wall and the bored piles according to the utility model;

[0026] In the figure: underground continuous wall 1, bored piles 2, high-pressure jet grouting piles 3, pre-buried grouting pipes 4, water-stop steel plates 5;

[0027] The underground continuous wall 1 comprises: a continuous wall reinforcement cage 1-1;

[0028] The bored pile 2 comprises: a bored pile reinforcement cage 2-1;

[0029] The pre-buried grouting pipe 4 comprises: a grouting hole 4-1;

[0030] The water stop steel plate 5 includes expansion bolts 5 - 1 . DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the utility model.

[0032] like Figure 2 As shown, the utility model provides a structure for improving the water stopping performance at the joints between underground continuous walls and bored cast-in-place piles, comprising adjacent underground continuous walls 1 and bored cast-in-place piles 2.

[0033] A continuous wall reinforcement cage 1 - 1 is arranged inside the underground continuous wall 1 , and a plurality of pre-buried grouting pipes 4 arranged vertically and spaced apart are connected to the outside of the continuous wall reinforcement cage 1 - 1 near the bored piles 2 .

[0034] A cast-in-place pile reinforcement cage 2-1 is arranged inside the bored cast-in-place pile 2, and a plurality of pre-buried grouting pipes 4 arranged at intervals and vertically are connected to the outer side of the cast-in-place pile reinforcement cage 2-1 near the underground continuous wall 1. The wall of the pre-buried grouting pipe 4 is drilled with a plurality of grouting holes 4-1 arranged at intervals, and cement slurry is injected into the pre-buried grouting pipe 4.

[0035] Specifically, the upper and lower ends of the wall of the pre-buried grouting pipe 4 are respectively grouting-stopping sections without drilling holes, and a plurality of grouting holes 4 - 1 are arranged in the middle section of the wall of the pre-buried grouting pipe 4 .

[0036] Preferably, the plurality of pre-buried grouting pipes 4 outside the cast-in-place pile reinforcement cage 2-1 are distributed at intervals in an arc shape.

[0037] Preferably, the bottom end of the pre-buried grouting pipe 4 extends to the bottom of the underground continuous wall 1 and the bottom of the bored hole of the bored pile 2 respectively.

[0038] Preferably, the pre-buried grouting pipe 4 is tied and connected to the continuous wall reinforcement cage 1-1 and the cast-in-place pile reinforcement cage 2-1 respectively.

[0039] The technical parameters of the pre-buried grouting pipe are as follows:

[0040] ① The grouting pipe adopts sleeve valve pipe, and the grouting liquid adopts cement slurry with a slurry ratio of 0.5:1 and the cement grade is not less than 42.5;

[0041] ② Grouting pressure 0.15~0.2MPa;

[0042] ③ The bottom end of the pre-buried grouting pipe extends to the bottom of the underground continuous wall and the bottom of the bored pile hole. The grouting section can be 0.2 to 0.3 m according to different strata;

[0043] ④ The slurry diffusion radius should be determined based on the on-site grouting test, but should not be less than 250mm;

[0044] ⑤ Grouting can be terminated when one of the following conditions is met:

[0045] a. Grouting volume (0.5m per linear meter) 3 ) and grouting pressure (0.2MPa) meet the design requirements; b. The grouting volume has reached 75% of the design value, and the grouting pressure exceeds the design value;

[0046] ⑥After grouting is completed, use 0.5:1 cement slurry to pressure seal the grouting holes.

[0047] The inner and outer spaces of the continuous wall reinforcement cage 1-1 are filled with concrete, and the inner and outer spaces of the cast-in-place pile reinforcement cage 2-1 are filled with concrete.

[0048] The technical parameters of bored pile hole forming are as follows:

[0049] ① During the drilling process of bored piles, the hole should always be filled with mud to keep the hole wall stable;

[0050] ② During the drilling process, the stability observation should be strengthened. If the hole wall has serious local collapse, it should be backfilled in time and properly handled;

[0051] ③ During construction, mud leakage should be replenished in time, the required liquid level should be maintained at all times, the mud quality should be checked regularly, and the mud indicators should be adjusted in time;

[0052] ④ After the hole section is excavated, the hole position, hole depth, hole width and hole wall verticality should be checked. Only after they are qualified can the hole be cleaned and the slurry replaced;

[0053] ⑤ The control of the final hole depth of the hole section shall meet the following requirements: a. The final hole depth of the hole section must meet the design depth. The excavation depth of the bottom of the hole in the same hole section shall be consistent and flat; b. The bottom of the hole of the extended section of the bored pile in the same hole section shall be consistent with the bottom excavation depth of the first-stage hole section;

[0054] ⑥ The length, thickness, inclination, etc. of bored piles shall meet the following requirements:

[0055] a. The allowable deviation of bored pile length is ±1.0~3.0%;

[0056] b. The allowable deviation of bored pile thickness is ±8~12mm;

[0057] c. The allowable deviation of the verticality of bored piles is ±1 / 320~1 / 280;

[0058] d. The local protrusion of the retaining pile surface is less than or equal to 100mm;

[0059] ⑦ After the hole is dug, the sediment and other debris at the bottom of the hole should be cleaned up. One hour after the hole bottom cleaning and mud replacement are completed, the mud density within 500mm height of the hole bottom shall not exceed 1.15, and the sediment thickness shall not exceed 100mm.

[0060] The technical parameters of underground continuous wall trenching are as follows:

[0061] ① During the trenching process of underground continuous wall, the trench should always be filled with mud to keep the trench wall stable;

[0062] ② During the trenching process, the stability observation should be strengthened. If a serious local collapse of the trench wall occurs, it should be backfilled in time and properly handled;

[0063] ③ During construction, mud leakage should be replenished in time, the required liquid level should be maintained at all times, the mud quality should be checked regularly, and the mud indicators should be adjusted in time;

[0064] ④ After the trench section is excavated, the trench position, trench depth, trench width and trench wall verticality should be checked. Only after they meet the requirements can the trench be cleaned and the slurry replaced;

[0065] ⑤ The control of the final trench depth of the trench section shall meet the following requirements: a. The final trench depth of the trench section must meet the design depth. The trench bottom excavation depth in the same trench section shall be consistent and kept flat; b. The trench bottom of the underground continuous wall in the same trench section shall be consistent with the trench bottom excavation depth of the first-phase trench section;

[0066] ⑥ The length, thickness, inclination, etc. of the underground continuous wall shall meet the following requirements:

[0067] a. The allowable deviation of underground continuous wall length is ±1.0~3.0%;

[0068] b. The allowable deviation of underground continuous wall thickness is ±8~12mm;

[0069] c. The allowable deviation of the verticality of underground continuous wall is ±1 / 320~1 / 280;

[0070] d. The local protrusion of the retaining pile surface is less than or equal to 100mm;

[0071] ⑦ After trenching, the sediment and other debris at the bottom of the trench should be cleaned up. One hour after the trench bottom cleaning and mud replacement are completed, the mud density within 500mm height of the trench bottom shall not exceed 1.15, and the sediment thickness shall not exceed 100mm.

[0072] Preferably, the grouting holes 4 - 1 are arranged in a plum blossom shape, with an opening diameter of 8 to 12 mm and a hole spacing of 20 to 30 cm.

[0073] The underground continuous wall 1 and bored cast-in-place piles 2 are fixedly attached to the inner side surfaces of the excavated foundation pit corresponding to a plurality of water-stopping steel plates 5 arranged in sequence from top to bottom, and the gaps enclosed between each of the water-stopping steel plates 5 and the underground continuous wall 1 and bored cast-in-place piles 2 are filled with cement slurry.

[0074] Preferably, each of the water-stopping steel plates 5 is fixedly connected to the underground continuous wall 1 and the bored cast-in-place piles 2 via expansion bolts 5 - 1 .

[0075] The technical parameters of the water-stop steel plate of the utility model are as follows:

[0076] ① The steel specification of the water-stop steel plate is Q235b, with a thickness of 10mm. The width of the foundation pit is 800-1000mm, and the height direction can be divided into several water-stop steel plates with a height of about 1000mm for on-site installation;

[0077] ②D22 connection holes are set at the left and right ends of the water-stop steel plate. The connection holes can be processed in the factory in advance. After on-site installation and positioning, D22 expansion bolts are used to anchor them into the ground-connected wall and bored piles;

[0078] Waterstop steel plate construction steps:

[0079] The first step is to clean and level the concrete on the inner side of the ground-anchored wall and bored piles;

[0080] The second step is to position the water stop steel plate, drill holes for expansion bolts, and reinforce the water stop steel plate;

[0081] The third step is to seal the gaps around the water-stop steel plate with a leak-proof sealer;

[0082] The fourth step is to fill the gaps between the waterstop steel plate, the ground-anchored wall and the bored piles with grouting material.

[0083] Compared with the prior art CN210368983U, it has the following differences:

[0084]

[0085] The specific implementation of the utility model is as follows:

[0086] ①Pre-buried grouting pipe production: Drill holes in the finished steel pipe in the manufacturing workshop according to the design requirements, and weld them into shape in sections;

[0087] ② Installation of pre-buried grouting pipes: After the pre-buried grouting pipes are processed, they are tied firmly to the continuous wall reinforcement cage and the cast-in-place pile reinforcement cage, and numbered in sections after acceptance;

[0088] ③Underground continuous wall construction: construction of guide wall, trench excavation, mud wall protection, trench bottom cleaning, lowering and tying the steel cage for pre-buried grouting pipes, and pouring underwater concrete;

[0089] ④ Bored pile construction: hole excavation, mud wall protection, hole bottom cleaning, lowering and tying the steel cage for pre-buried grouting pipes, and pouring underwater concrete;

[0090] ⑤ Grouting of pre-buried grouting pipes: After the underground continuous wall and bored cast-in-place piles reach the designed strength and before the foundation pit excavation construction, grouting of pre-buried grouting pipes shall be carried out on the ground. The grouting shall be carried out in sections and at intervals to improve the grouting quality.

[0091] ⑥ Construction of water-stop steel plates: In order to reduce the risk of leakage at the joints of underground continuous walls and bored cast-in-place piles during foundation pit excavation due to inconsistent stiffness, and to prevent mud from being trapped in the joints of underground continuous walls and bored cast-in-place piles during unloading of earth in the foundation pit, and to prevent leakage after the balance between the inside and outside of the foundation pit is destroyed, water-stop steel plates are laid layer by layer during the foundation pit excavation process (from top to bottom in layered excavation), and the water-stop steel plates are fixed to the underground continuous walls and bored cast-in-place piles with expansion bolts.

[0092] The utility model discloses to improve the structure of the water-stopping performance at the joint of the underground continuous wall and the bored cast-in-place pile, improve the water-stopping performance at the joint of the underground continuous wall and the bored cast-in-place pile, enhance the shear strength at the joint position, reduce the number of high-pressure rotary jet piles arranged at the joint of the two, and avoid the trouble of insufficient operating space.

[0093] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principle of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A structure for improving the water-stopping performance at the joint between an underground continuous wall and a bored pile, comprising adjacent underground continuous walls (1) and bored piles (2), characterized in that: A continuous wall steel cage (1-1) is arranged inside the underground continuous wall (1), and a plurality of pre-buried grouting pipes (4) arranged vertically and spaced apart are connected to the outside of the continuous wall steel cage (1-1) near the bored piles (2); A bored pile reinforcement cage (2-1) is arranged inside the bored pile (2), and a plurality of pre-buried grouting pipes (4) arranged vertically and spaced apart are connected to the outer side of the bored pile reinforcement cage (2-1) near the underground continuous wall (1); The inner and outer spaces of the continuous wall reinforcement cage (1-1) are filled with concrete, the inner and outer spaces of the cast-in-place pile reinforcement cage (2-1) are filled with concrete, a plurality of grouting holes (4-1) arranged at intervals are drilled in the wall of the pre-buried grouting pipe (4), and cement slurry is injected into the pre-buried grouting pipe (4); The underground continuous wall (1) and bored cast-in-place piles (2) are fitted and fixed with a plurality of water-stopping steel plates (5) arranged in sequence from top to bottom on the inner side surfaces of the excavated foundation pit, and the gaps formed between each of the water-stopping steel plates (5) and the underground continuous wall (1) and bored cast-in-place piles (2) are filled with cement slurry.

2. The structure for improving the water-stopping performance at the joint between underground continuous wall and bored pile according to claim 1, characterized in that: The underground continuous wall (1) and bored pile (2) have length tolerances of ±1.0-3.0%, thickness tolerances of ±8-12 mm, verticality tolerances of ±1 / 320-1 / 280, and local surface protrusions of less than or equal to 100 mm.

3. The structure for improving the water-stopping performance at the joint between underground continuous wall and bored pile according to claim 1, characterized in that: The grouting holes (4-1) are arranged in a plum blossom shape, with a hole diameter of 8 to 12 mm and a hole spacing of 20 to 30 cm.

4. The structure for improving the water-stopping performance at the joint between underground continuous wall and bored pile according to claim 3 is characterized in that: The upper and lower ends of the wall of the pre-buried grouting pipe (4) are respectively grouting-stopping sections without drilling holes, and a plurality of grouting holes (4-1) are arranged in the middle section of the wall of the pre-buried grouting pipe (4).

5. The structure for improving the water-stopping performance at the joint between underground continuous wall and bored pile according to claim 4, characterized in that: A plurality of pre-buried grouting pipes (4) outside the cast-in-place pile reinforcement cage (2-1) are distributed at intervals in an arc shape.

6. The structure for improving the water-stopping performance at the joint between underground continuous wall and bored pile according to claim 5, characterized in that: The bottom ends of the pre-buried grouting pipes (4) extend to the bottom of the underground continuous wall (1) and the bottom of the bored holes of the bored piles (2) respectively.

7. The structure for improving the water-stopping performance at the joint between underground continuous wall and bored pile according to claim 6, characterized in that: The pre-buried grouting pipe (4) is tied and connected to the continuous wall reinforcement cage (1-1) and the cast-in-place pile reinforcement cage (2-1) respectively.

8. The structure for improving the water-stopping performance at the joint between underground continuous wall and bored pile according to claim 1, characterized in that: Each of the water-stopping steel plates (5) is fixedly connected to the underground continuous wall (1) and the bored cast-in-place piles (2) via expansion bolts (5-1).

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