CN116289971A

CN116289971A - Underground combined supporting structure of deep foundation pit adjacent building and construction method thereof

Info

Publication number: CN116289971A
Application number: CN202211575302.2A
Authority: CN
Inventors: 何旭升; 陈正; 杨磊; 李旭锋; 吴双平; 王亮; 周洋; 陈雁; 程帆; 杨明杰; 张晓峰; 周颖; 刘莹; 马少坤
Original assignee: Nanning Rail Transit Co ltd; Guangxi University; China Railway First Survey and Design Institute Group Ltd; China Railway First Engineering Group Co Ltd
Current assignee: Nanning Rail Transit Co ltd; Guangxi University; China Railway First Survey and Design Institute Group Ltd; China Railway First Engineering Group Co Ltd
Priority date: 2022-12-08
Filing date: 2022-12-08
Publication date: 2023-06-23

Abstract

An underground combined supporting structure of a deep foundation pit adjacent building and a construction method thereof comprise an underground continuous wall, isolation piles, sleeve valve pipes, crown beams and pull beams. Sleeve valve pipes are pre-buried between the underground diaphragm wall and the isolation piles, crown beams are arranged at the tops of the underground diaphragm wall, the tops of adjacent isolation piles are connected by the crown beams, and pull beams are used for connecting the crown beams of the underground diaphragm wall and the crown beams of the isolation piles, so that the underground diaphragm wall-isolation pile combined supporting structure is formed. During construction, the isolation piles and the crown beams are firstly constructed, and then the underground diaphragm wall and the crown beams are constructed. By adopting the method, the deformation of soil bodies inside and outside the pit and the additional deformation of adjacent buildings can be effectively controlled, and the safety of the deep foundation pit adjacent to the buildings during excavation is protected.

Description

Underground combined supporting structure of deep foundation pit adjacent building and construction method thereof

Technical Field

The invention relates to the technical field of foundation pit support, in particular to an underground combined support structure of a deep foundation pit adjacent building and a construction method thereof.

Background

Subway stations are usually built in urban building dense areas, in the process of subway station construction, the disturbance effect of excavation of station foundation pits can influence surrounding buildings, and if a foundation pit supporting method is unreasonable, deformation and damage of the surrounding buildings can be possibly caused. The past accidents caused by the failure of a plurality of deep foundation pit supporting structures show that the reliability of the subway foundation pit supporting method is important to ensuring the stability of surrounding buildings. The search for effective deep foundation pit supporting structures to ensure the safety of surrounding buildings has become a focus of attention in the subway foundation pit engineering construction process.

Disclosure of Invention

In order to seek an effective deep foundation pit supporting structure to ensure the safety of surrounding buildings, the invention combines the characteristic advantages of underground continuous walls and isolation piles, and provides an underground combined supporting structure of a deep foundation pit adjacent building and a construction method thereof.

In order to achieve the above object, the present invention has the technical scheme that: the underground combined supporting structure of the deep foundation pit adjacent building comprises the following components of an underground continuous wall, isolation piles, sleeve valve pipes, crown beams and pull beams, wherein the concrete structure and the connection relation of the components are as follows: sleeve valve pipes are pre-buried between the underground diaphragm wall and the isolation piles, crown beams are arranged at the tops of the underground diaphragm wall, the tops of adjacent isolation piles are connected by the crown beams, and then the crown beams of the underground diaphragm wall and the crown beams of the isolation piles are connected by the pull beams, so that an integral underground diaphragm wall-isolation pile combined supporting structure is formed.

The isolation pile is a reinforced concrete bored pile, the type is a round pile, the pile length of the isolation pile is 22.5m, the pile diameter and the distance between the isolation pile and the ground continuous wall are respectively 800mm and 1000mm, and the isolation pile is arranged at the position 2m away from the underground continuous wall outside the foundation pit.

The underground diaphragm wall is made of reinforced concrete, the thickness of the wall body of the underground diaphragm wall is 800mm, and the insertion depth is 33m.

The beam material is reinforced concrete, the section size is 400 multiplied by 800mm, and the distance between adjacent beams is 6m.

The crown beam material is reinforced concrete, and the cross section size is 800 multiplied by 800mm.

And the sleeve valve pipe is filled with cement-water glass double-liquid slurry, and the length of the pipe body is 6m.

The construction method of the underground combined supporting structure of the deep foundation pit adjacent to the building comprises the following construction steps:

s1, setting isolation piles at proper distances from a building foundation pit, wherein adjacent isolation piles are connected by arranging crown beams at pile tops;

s2, constructing underground continuous walls along the periphery of the foundation pit, and arranging crown beams on the tops of the underground continuous walls;

s3, grouting sleeve valve pipes are pre-buried between the underground diaphragm wall and the isolation piles;

s4, connecting an underground continuous wall crown beam and an isolation pile crown beam by a construction pull beam;

s5, excavating earthwork of the deep foundation pit, and constructing an inner support.

The construction method of the underground combined supporting structure of the deep foundation pit adjacent to the building is to construct an underground continuous wall crown beam, manually break the wall head of the underground continuous wall, straighten reserved steel bars, and anchor the underground continuous wall steel bars into the crown beam, wherein the anchoring length is required to meet the standard requirement.

The construction method of the underground combined supporting structure of the deep foundation pit adjacent to the building comprises the steps of firstly constructing the isolation piles and then constructing the underground continuous wall during construction.

Compared with the prior art, the invention has the advantages that:

1. the application range is wide, the construction of the isolation pile-underground continuous wall foundation pit combined supporting structure has small disturbance to the soil body of the foundation pit excavation site, and the combined supporting structure is suitable for various soil layers.

2. The construction safety is improved, and the possibility of occurrence of construction accidents of the deep foundation pit is reduced. Because the foundation pit supporting and excavating technology is complex, the method has wide range of relation and multiple variation factors, and is the most challenging technical difficulty in the construction engineering. After the isolation pile-underground continuous wall foundation pit combined supporting structure is formed, the rigidity is high, and the integrity is good. During excavation of the foundation pit, the combined support is small in deformation, soil body bulge in the pit can be effectively reduced, soil body sedimentation and soil body lateral displacement after the pit are reduced, disturbance to adjacent buildings of the foundation pit can be further reduced, and additional deformation of the adjacent buildings caused by foundation pit construction is effectively reduced.

3. The construction efficiency is improved, and the construction period delay caused by improper construction method is avoided. By selecting a proper foundation pit support design method and construction technology, the problems of reworking and the like can be effectively avoided, the construction progress is ensured, and the economic loss caused by the problem of construction efficiency is avoided. During construction of the isolation pile, the underground diaphragm wall reinforcement cage can be manufactured, the site construction efficiency is improved, and the construction period is shortened.

4. The construction cost is saved, and the waste caused by improper design method and construction technology selection, improper control of construction process and improper treatment of reinforcement measures is reduced.

Drawings

Fig. 1 is a three-dimensional schematic perspective view of an underground joint support structure of a deep foundation pit adjacent building according to the present invention.

Fig. 2 is a plan view of an underground joint support structure of a deep foundation pit adjacent to a building according to the present invention.

Marked in the figure as: the building construction system comprises an isolation pile 1, an underground diaphragm wall 2, a pull beam 3, a sleeve valve pipe 4, an isolation pile crown beam 5, an underground diaphragm wall crown beam 6, an inner support 7 and an adjacent building 8.

Detailed Description

The technical scheme of the invention is further described below with reference to the accompanying drawings and examples.

Example 1

As shown in fig. 1 and 2, the underground combined supporting structure of the deep foundation pit adjacent to a building comprises the following components: sleeve valve pipes 4 are pre-buried between the underground diaphragm wall 2 and the isolation piles 1, the pile top crown beams 5 of the isolation piles 1 and the wall top crown beams 6 of the underground diaphragm wall 2 are connected through the pull beams 3, and an integral underground diaphragm wall isolation pile combined supporting structure is formed.

Example 2

An example of the construction method of the underground combined supporting structure of the deep foundation pit adjacent to the building comprises the following construction steps:

(1) Arranging 1 row of isolation piles 1 phi 800@1000 at the position 2 meters outside the underground diaphragm wall 2 of the foundation pit, drilling and processing reinforcement cages by the isolation piles 1, arranging the reinforcement cages by the isolation piles, chiseling off pile heads of the isolation piles 1, binding reinforcement bars of isolation pile crown beams 5, and connecting adjacent isolation piles 1 by adopting 800X 800mm isolation pile crown beams 5 to form an integrated soil retaining structure as a reinforcing measure;

(2) Constructing underground diaphragm walls 2 with the thickness of 0.8m along the periphery of a foundation pit, pouring guide walls, processing reinforcement cages of the underground diaphragm walls 2, performing grooving construction, adopting C35 underwater concrete and water-stop curtains, constructing underground diaphragm wall crown beams 6, performing pile head slurry treatment on the underground diaphragm walls 2, manually breaking the wall heads of the underground diaphragm walls 2, straightening reserved reinforcement bars, and anchoring the reinforcement bars of the underground diaphragm walls 2 into the underground diaphragm wall crown beams 6;

(3) The sleeve valve pipe 4 is drilled, grouting is carried out on the sleeve valve pipe 4 of the 1 row is pre-buried between the underground diaphragm wall 2 and the isolation pile 1, cement-water glass double-oar liquid tracking grouting is adopted, the foundation is reinforced, the risk of lateral shifting caused by soil stress loss is further reduced, the lateral deformation of the soil is effectively prevented, and the safety of surrounding buildings is ensured;

(4) And the construction bracing beam is connected with the underground continuous wall crown beam 6 and the isolation pile crown beam 5 to form a combined supporting structure, so that the structural integrity is improved.

(5) Pavement concrete is broken, earthwork is excavated layer by layer, and the first, second and third inner supports 7 are constructed, so that the deformation resistance of the structure is improved.

Working principle and process:

the unloading process of the excavation surface of the foundation pit can cause stress release of soil in the pit, the pressure difference between the inside and the outside of the pit is increased, the soil in the pit is raised, the soil outside the pit is settled to different degrees, the settlement of the long side of the foundation pit is larger than the settlement of the short side, an obvious constraint effect exists at the corner point of the foundation pit, and the soil settlement at the corner point is obviously smaller than other parts. Aiming at the soil body sliding deformation caused by excavation, the local underground diaphragm wall-isolation pile combined supporting structure penetrates through a soil body sliding surface to be embedded into a deep soil body, and the deformation of the soil body inside and outside the pit is restrained by improving the shearing resistance of the sliding surface and the pile side resistance provided by the pile body of the isolation pile. The soil body in the pit is removed, so that the soil pressure and the water pressure outside the combined supporting structure are obviously greater than the pressure inside the combined supporting structure, the combined supporting structure generates deformation, the lateral displacement of the combined supporting structure points to the pit, the deformation of the two ends of the underground diaphragm wall is small, the deformation of the middle part of the underground diaphragm wall is large, the distance between the isolation piles is further, and the deformation of the pile body is slightly smaller than that of the underground diaphragm wall. The integral deformation of the combined support is small and far smaller than the standard limit value, and the good stress system can reduce the interaction of soil bodies on two sides of the support structure, so that the influence of soil disturbance on the adjacent foundation pit building is reduced, and the safety of the adjacent building during excavation is ensured.

Although the invention has been described above with reference to the accompanying drawings, the invention is not limited to the above-described embodiments, which are given by way of illustration only and not by way of limitation, and other modifications can be made by those skilled in the art without departing from the scope of the invention, which is intended to be included in the protection of the invention.

Claims

1. The underground combined supporting structure of the deep foundation pit adjacent building is characterized in that the component members comprise underground continuous walls, isolation piles, sleeve valve pipes, crown beams and pull beams, and the specific structure and the connection relation of the component members are as follows: sleeve valve pipes are pre-buried between the underground diaphragm wall and the isolation piles, crown beams are arranged at the tops of the underground diaphragm wall, the tops of adjacent isolation piles are connected by the crown beams, and then the crown beams of the underground diaphragm wall and the crown beams of the isolation piles are connected by the pull beams, so that an integral underground diaphragm wall-isolation pile combined supporting structure is formed.

2. The underground combined supporting structure of the deep foundation pit adjacent to the building according to claim 1, wherein the isolation piles are reinforced concrete bored piles in the form of round piles, the pile length of the isolation piles is 22.5m, the pile diameter and the distance between the isolation piles are 800mm and 1000mm respectively, and the isolation piles are arranged at the position 2m away from the underground continuous wall outside the foundation pit.

3. The underground joint support structure of the deep foundation pit adjacent building according to claim 1, wherein the underground diaphragm wall material is reinforced concrete, the thickness of the underground diaphragm wall is 800mm, and the insertion depth is 33m.

4. The underground joint support structure of a deep foundation pit adjacent to a building according to claim 1, wherein the tie beam material is reinforced concrete, the cross-sectional dimension is 400 x 800mm, and the spacing between adjacent tie beams is 6m.

5. The underground joint support structure of a deep foundation pit adjacent building according to claim 1, wherein the crown beam material is reinforced concrete, and the cross-sectional dimension is 800 x 800mm.

6. The underground combined support structure of the deep foundation pit adjacent building according to claim 1, wherein the sleeve valve pipe is filled with cement-water glass double slurry, and the length of the pipe body is 6m.

7. The construction method of the underground combined support structure of the deep foundation pit adjacent building according to claim 1, comprising the following construction steps:

8. The construction method of the underground combined supporting structure of the deep foundation pit adjacent building according to claim 1, wherein the underground diaphragm wall crown beam is constructed, the underground diaphragm wall head is manually broken, reserved steel bars are straightened, the underground diaphragm wall steel bars must be anchored in the crown beam, and the anchoring length meets the standard requirements.

9. The method for constructing an underground joint support structure of a deep foundation pit adjacent to a building according to claim 7, wherein the construction is performed by constructing the isolation piles and then constructing the underground diaphragm wall.