Structure for improving water stop performance of secant pile

Abstract

The utility model discloses a structure for improving the waterstop performance of a secant pile. The structure comprises a plain concrete A-type pile and a reinforced concrete B-type pile which are located in a drilled hole and are in a crossed and meshed shape, the plain concrete A-type pile is filled with concrete, and a reinforcement cage is arranged in the reinforced concrete B-type pile. A plurality of pre-embedded grouting pipes which are vertically arranged at intervals are arranged on the periphery of the reinforcement cage and correspond to lap joint sections of the adjacent plain concrete A-shaped piles, a plurality of grouting holes which are arranged at intervals are formed in the pipe walls of the pre-embedded grouting pipes, the inner space and the outer space of the reinforcement cage are filled with concrete, and cement grout is injected into the pre-embedded grouting pipes. According to the utility model, the water stop performance of the side wall of the foundation pit with large excavation depth and high underground water level is improved, the shear strength of the occluded joint position is enhanced, the application range of the occluded cast-in-place pile is expanded, and the construction safety of the foundation pit is improved.

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 a bite 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] The construction process of interlocking cast-in-place piles is relatively simple, the support rigidity is large, and the cost is lower than that of underground continuous walls. Therefore, they are promoted and applied in some foundation pit projects. Interlocking cast-in-place piles are achieved by successively constructing bored cast-in-place piles to achieve the purpose of water stopping. They include cross-interlocking plain concrete piles of type A piles and reinforced concrete piles of type B piles. The construction process of bored cast-in-place piles is as follows: holes are excavated on the ground under the condition of mud wall protection by rotary drilling equipment, and then the steel cage is suspended after drilling and cleaning the groove, and underwater concrete is poured by the catheter method to form a cast-in-place pile. The B-type pile hole must be started after the initial setting of the A-type pile and before the final setting, so as to achieve the interlocking of the cast-in-place pile. This cycle is carried out to build a continuous interlocking cast-in-place pile underground.

[0004] However, in the actual application of interlocking cast-in-place piles, there are the following water-stopping problems:

[0005] First, there is mud skin at the joints of the underwater concrete poured successively between adjacent interlocking cast-in-place piles, which is easy to form a weak water-stopping zone. In addition, there is a vertical deviation during the construction of bored cast-in-place piles, which leads to a further reduction in the plane arc length of the interlocking lower part of the bored cast-in-place piles. The interlocking area of ​​each bored cast-in-place pile is easy to form a seepage channel under the action of high pressure water. Therefore, interlocking cast-in-place piles are not suitable for foundation pit projects with high pressure head and large excavation depth, and their application scope is relatively small.

[0006] Second, during the excavation of the interlocking cast-in-place pile foundation pit, if water seepage and sand leakage occur in the joints, ground grouting reinforcement filling or high-pressure rotary jet pile reinforcement is generally carried out on the outside of the foundation pit. However, this measure requires a sufficiently large construction site and cannot be implemented if there are underground pipelines in the surrounding area. 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 of interlocking piles, thereby improving the water-stopping performance of the side walls of foundation pits with large excavation depths and high groundwater levels, enhancing the shear strength of interlocking joints, expanding the application scope of interlocking cast-in-place piles, and avoiding the use of ground grouting reinforcement filling or high-pressure rotary jet pile reinforcement.

[0008] In order to achieve the above-mentioned purpose, the utility model is designed to improve the water-stopping performance of interlocking piles, including plain concrete type A piles and reinforced concrete type B piles located inside a drilled hole and in a cross-interlocking shape. The structure is special in that: the plain concrete type A piles are filled with concrete, and the reinforced concrete type B piles are provided with steel cages, and the outer periphery of the steel cage is provided with a plurality of pre-buried grouting pipes arranged at intervals and vertically corresponding to the overlapping sections with adjacent plain concrete type A piles, the wall of the pre-buried grouting pipes is opened with a plurality of grouting holes arranged at intervals, the space inside and outside the steel cage is filled with concrete, and cement slurry is injected into the pre-buried grouting pipes.

[0009] Furthermore, a plurality of the pre-buried grouting pipes are arranged at intervals in an arc shape.

[0010] 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.

[0011] 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.

[0012] Furthermore, the pre-buried grouting pipe is fixedly connected to the steel cage.

[0013] Furthermore, the bottom end of the pre-buried grouting pipe extends to the bottom of the drilled hole.

[0014] Furthermore, the allowable deviation of the length of the plain concrete A-type pile and the reinforced concrete B-type pile is ±1.0-3.0%, the allowable deviation of the thickness is ±8-12mm, the allowable deviation of the verticality is ±1 / 320-1 / 280, and the local protrusion of the surface is less than or equal to 100mm.

[0015] Furthermore, the concrete of the plain concrete type A pile is filled with a retarder, and the concrete of the reinforced concrete type B pile is filled with an expansion agent.

[0016] The advantages of the utility model are:

[0017] 1. The utility model sets vertically spaced pre-buried grouting pipes at the outer periphery of the steel cage corresponding to the cross-engagement joint position with the adjacent plain concrete A-type pile, and ties the pre-buried grouting pipes with the steel cage of the reinforced concrete B-type pile together. After the construction of the reinforced concrete B-type pile is completed, after the occlusal cast-in-place pile reaches the design strength and before the foundation pit excavation construction, the pre-buried grouting pipes in the occlusal area are reinforced with cement grouting, thereby achieving the effect of improving the water-stopping performance of the joint and enhancing the shear strength of the occlusal surface, and ensuring the safety of the foundation pit excavation construction;

[0018] The utility model discloses the structure of the interlocking pile water-stopping performance is improved, the structure is simple, the construction speed is fast, the water-stopping performance of the side wall of the foundation pit with a large excavation depth and a high groundwater level is improved, the shear strength of the interlocking joint position is enhanced, and the application range of the interlocking pile is expanded, and the safety of the foundation pit construction is improved, and the use of ground grouting reinforcement filling or high-pressure rotary jet pile reinforcement is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the plan layout of the utility model;

[0020] In the figure: plain concrete A-type pile 1, reinforced concrete B-type pile 2;

[0021] The reinforced concrete B-type pile 2 comprises: a reinforcement cage 2-1, a pre-buried grouting pipe 2-2, and a grouting hole 2-3 (not shown in the figure). DETAILED DESCRIPTION

[0022] 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.

[0023] like Figure 1As shown, the utility model has a structure for improving the water-stopping performance of the interlocking pile, comprising a plain concrete type A pile 1 and a reinforced concrete type B pile 2 located inside a drilled hole and in a cross-interlocking shape, wherein the plain concrete type A pile 1 is filled with concrete, and the reinforced concrete type B pile 2 is provided with a steel cage 2-1, and the outer periphery of the steel cage 2-1 is provided with a plurality of pre-buried grouting pipes 2-2 arranged at intervals and vertically corresponding to the overlapping section with the adjacent plain concrete type A pile 1, and the wall of the pre-buried grouting pipe 2-2 is provided with a plurality of grouting holes 2-3 arranged at intervals, the inner and outer spaces of the steel cage 2-1 are filled with concrete, and cement slurry is injected into the pre-buried grouting pipe 2-2.

[0024] Preferably, a plurality of the pre-buried grouting pipes 2-2 are arranged at intervals in an arc shape.

[0025] In this embodiment, the pre-buried grouting pipes 2-2 are arranged in an arc shape at intervals outside the steel cage 2-1 in the bite area, and the plane arrangement spacing is 0.2 to 0.3m.

[0026] Specifically, the upper and lower ends of the pre-buried grouting pipe 2-2 are respectively non-drilled grouting sections, and a plurality of grouting holes 2-3 are arranged in the middle section of the pre-buried grouting pipe 2-2. In this embodiment, the length of the non-drilled grouting sections at the upper and lower ends of the pre-buried grouting pipe 2-2 is 0.5 to 1.5 m.

[0027] Specifically, the grouting holes 2-3 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. The technical parameters of the pre-buried grouting pipe 2-2 are as follows:

[0028] 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;

[0029] ② Grouting pressure 0.15~0.2MPa;

[0030] ③ The bottom end of the pre-buried grouting pipe 2-2 extends to the drill hole, and the grouting section can be 0.2 to 0.3 m according to different strata;

[0031] ④ The slurry diffusion radius should be determined based on the on-site grouting test, but should not be less than 250mm;

[0032] ⑤ Grouting can be terminated when one of the following conditions is met:

[0033] 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;

[0034] ⑥ After the grouting is completed, the grouting hole is pressure-sealed with 0.5:1 cement slurry. Specifically, the pre-buried grouting pipe 2-2 is fixedly connected to the steel cage 2-1. In this embodiment, the pre-buried grouting pipe 2-2 is tied and fixed to the steel cage 2-1.

[0035] The technical parameters of bored pile trenching are as follows:

[0036] ① During the drilling process of bored piles, the hole should always be filled with mud to keep the hole wall stable;

[0037] 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;

[0038] 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;

[0039] 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;

[0040] 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 designed 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 bored pile in the same hole section shall be consistent with the bottom excavation depth of the first-stage hole section;

[0041] ⑥ The length, thickness, inclination, etc. of bored piles shall meet the following requirements:

[0042] a. The allowable deviation of the length of plain concrete type A pile 1 and reinforced concrete type B pile 2 is ±1.0~3.0%;

[0043] b. The allowable thickness deviation of plain concrete type A pile 1 and reinforced concrete type B pile 2 is ±8~12mm;

[0044] c. The allowable verticality deviation of plain concrete type A pile 1 and reinforced concrete type B pile 2 is ±1 / 320~1 / 280;

[0045] d. The local protrusion of the retaining pile surface is less than or equal to 100mm;

[0046] e. There is no mud or water leakage at the joints between the plain concrete type A pile 1 and the reinforced concrete type B pile 2;

[0047] 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.

[0048] Preferably, the concrete of the plain concrete A-type pile 1 is filled with a retarder, and the concrete of the reinforced concrete B-type pile 2 is filled with an expansion agent.

[0049] In order to enhance the water-stopping performance between the plain concrete type A pile 1 and the reinforced concrete type B pile 2, on the basis of adding the pre-buried grouting pipe 2-2, a retarder is added during the concrete pouring of the plain concrete type A pile 1 to ensure that the reinforced concrete type B pile 2 can be smoothly drilled and engaged during the drilling process; an expansion agent is added during the concrete pouring of the reinforced concrete type B pile 2 to reduce the range of mud skin in the engaging area.

[0050] The specific implementation of the utility model is as follows:

[0051] 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;

[0052] ② Installation of pre-buried grouting pipe: After the pre-buried grouting pipe is processed, it is firmly tied to the steel cage and numbered in sections after passing the acceptance inspection;

[0053] ③ Construction of plain concrete A-type piles: construction of guide wall, hole excavation, mud wall protection, trench bottom cleaning, and pouring of underwater concrete;

[0054] ④Construction of reinforced concrete B-type piles: hole excavation, mud wall protection, trench bottom cleaning, tying the steel cage with pre-buried grouting pipe at the bottom, and pouring underwater concrete;

[0055] ⑤ Grouting of pre-buried grouting pipes: After the bored piles (cross-interlocking plain concrete type A piles and reinforced concrete type B piles) have reached the design 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.

[0056] Compared with the prior art CN114703838B, the utility model of this application has the following features:

[0057]

[0058] The utility model provides vertically spaced pre-buried grouting pipes at positions corresponding to the cross-intersecting joints with adjacent plain concrete A-type piles on the outer periphery of the steel cage, and ties the pre-buried grouting pipes together with the steel cage of the reinforced concrete B-type pile. After the construction of the reinforced concrete B-type piles is completed, after the interlocking cast-in-place piles reach the designed strength and before the foundation pit excavation construction, cement grouting reinforcement is performed on the pre-buried grouting pipes in the interlocking area, thereby achieving the effect of improving the water-stopping performance of the joints and enhancing the shear strength of the interlocking surfaces, thereby ensuring the safety of the foundation pit excavation construction.

[0059] 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 of an interlocking pile, comprising a plain concrete A-type pile (1) and a reinforced concrete B-type pile (2) located inside a borehole and in a cross-interlocking shape, characterized in that: The plain concrete A-type pile (1) is filled with concrete, the reinforced concrete B-type pile (2) is provided with a steel cage (2-1), the outer periphery of the steel cage (2-1) is provided with a plurality of pre-buried grouting pipes (2-2) arranged at intervals and vertically corresponding to the overlap section with the adjacent plain concrete A-type pile (1), the wall of the pre-buried grouting pipe (2-2) is provided with a plurality of grouting holes (2-3) arranged at intervals, the inner and outer spaces of the steel cage (2-1) are filled with concrete, and cement slurry is injected into the pre-buried grouting pipe (2-2).

2. The structure for improving the water-stopping performance of the occlusal pile according to claim 1, characterized in that: A plurality of pre-buried grouting pipes (2-2) are arranged at intervals in an arc shape.

3. The structure for improving the water-stopping performance of the occlusal pile according to claim 2, characterized in that: The upper and lower ends of the wall of the pre-buried grouting pipe (2-2) are respectively grouting-stopping sections without drilling holes, and a plurality of grouting holes (2-3) are arranged in the middle section of the wall of the pre-buried grouting pipe (2-2).

4. The structure for improving the water-stopping performance of the occlusal pile according to claim 3 is characterized in that: The grouting holes (2-3) 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.

5. The structure for improving the water-stopping performance of the occlusal pile according to claim 4, characterized in that: The pre-buried grouting pipe (2-2) is fixedly connected to the steel cage (2-1).

6. The structure for improving the water-stopping performance of the occlusal pile according to claim 5, characterized in that: The bottom end of the pre-buried grouting pipe (2-2) extends to the bottom of the drilled hole.

7. The structure for improving the water-stopping performance of the occlusal pile according to claim 1, characterized in that: The plain concrete A-type pile (1) and reinforced concrete B-type pile (2) have a length tolerance of ±1.0-3.0%, a thickness tolerance of ±8-12 mm, a verticality tolerance of ±1 / 320-1 / 280, and a local surface protrusion of less than or equal to 100 mm.

8. The structure for improving the water-stopping performance of the occlusal pile according to claim 7, characterized in that: The concrete of the plain concrete A-type pile (1) is filled with a retarder, and the concrete of the reinforced concrete B-type pile (2) is filled with an expansion agent.

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