CN115595985A - Foundation pit supporting structure under narrow space condition and construction method thereof - Google Patents

Abstract

The invention discloses a foundation pit supporting structure under a narrow space condition and a construction method thereof, wherein the construction method comprises the following steps: constructing a first row of triaxial mixing piles under a narrow space condition; after the first row of triaxial mixing piles reaches a first preset strength, overlapping and constructing a second row of triaxial mixing piles on one side of the first row of triaxial mixing piles to form overlapped triaxial mixing piles; and after the superposed triaxial mixing pile reaches a second preset strength, constructing a rotary excavating filling pile along the center of the superposed triaxial mixing pile, and arranging the rotary excavating filling pile in the superposed triaxial mixing pile to form a foundation pit supporting structure. The invention can ensure the construction quality and reduce the construction cost under the condition of narrow space.

Description

Foundation pit supporting structure under narrow space condition and construction method thereof

Technical Field

The invention relates to the technical field of constructional engineering, in particular to a foundation pit supporting structure under a narrow space condition and a construction method thereof.

Background

The construction method aims at the foundation pit supporting structure, in particular to the construction engineering which aims at the problems that the basement outer wall is too close to the foundation pit supporting structure, and the subway, the auxiliary air shaft and other existing building protection requirements are high. In the engineering project with narrow site and complex surrounding environment, the conventional selection of the foundation pit supporting structure is the SMW construction method pile and the underground continuous wall. The SMW construction method pile has the problems that the section steel deformation is large, the construction quality is difficult to control, and the like; the problems of high cost, complex construction operation and the like exist in the construction of the underground diaphragm wall. Therefore, how to carry out foundation pit supporting structure construction under the narrow and small space condition can guarantee construction quality, can reduce construction cost becomes the technological problem that needs to solve in this field urgently.

Disclosure of Invention

The invention aims to provide a foundation pit supporting structure under a narrow space condition and a construction method thereof, and aims to solve the problems of high cost, poor quality and limited site in the construction of the traditional foundation pit supporting structure.

In order to solve the technical problems, the technical scheme provided by the invention is as follows: a construction method of a foundation pit supporting structure under the condition of a narrow space comprises the following steps:

constructing a first row of triaxial mixing piles under a narrow space condition;

after the first row of triaxial mixing piles reaches a first preset strength, overlapping and constructing a second row of triaxial mixing piles on one side of the first row of triaxial mixing piles to form overlapped triaxial mixing piles;

and after the superposed triaxial mixing pile reaches a second preset strength, constructing a rotary excavating filling pile along the center of the superposed triaxial mixing pile, and arranging the rotary excavating filling pile in the superposed triaxial mixing pile to form a foundation pit supporting structure.

Further, according to the construction method of the foundation pit supporting structure under the narrow space condition, the first row of the three-axis stirring piles is an outer row of the three-axis stirring piles, and the second row of the three-axis stirring piles is an inner row of the three-axis stirring piles.

Further, according to the construction method of the foundation pit supporting structure under the narrow space condition, the first row of triaxial mixing piles is inner row triaxial mixing piles, and the second row of triaxial mixing piles is outer row triaxial mixing piles

Further, according to the construction method of the foundation pit supporting structure under the narrow space condition, the first preset strength is 3 days.

Further, according to the construction method of the foundation pit supporting structure under the narrow space condition, the second preset strength is 28 days.

Further, according to the construction method of the foundation pit supporting structure under the narrow space condition, a three-shaft stirring pile is constructed through a three-shaft stirring pile machine by adopting a two-stirring and two-spraying stirring process.

Further, according to the construction method of the foundation pit supporting structure under the narrow space condition, cement and soil are forcibly stirred in situ at the deep part of the soil layer through the triaxial mixing pile machine, and the cement soil consolidation body with certain strength is formed to form the triaxial mixing pile by utilizing the physical and chemical actions between the soil and cement hydrate.

Further, according to the construction method of the foundation pit supporting structure under the narrow space condition, provided by the invention, the triaxial mixing pile machine is used for mixing the cement and the soil by adopting two-axis co-rotating guniting, and the middle-axis reverse high-pressure air injection is fully stirred and mixed with the cement in the hole to form the triaxial mixing pile.

In order to solve the above technical problems, another technical solution provided by the present invention is: a foundation pit supporting structure under narrow and small space condition includes:

overlapping three-axis stirring piles, wherein a first row of three-axis stirring piles and a second row of three-axis stirring piles are overlapped;

and the rotary excavating cast-in-place pile is arranged in the superposed triaxial stirring pile.

Further, according to the foundation pit supporting structure under the condition of the narrow space, the second row of the triaxial mixing piles are arranged on the inner side or the outer side of the first row of the triaxial mixing piles in an overlapped mode.

Compared with the prior art, the invention has the following beneficial effects:

according to the foundation pit supporting structure and the construction method thereof under the narrow space condition, the formed foundation pit supporting structure achieves a good water stopping effect through the superposed triaxial mixing piles, and achieves a good soil retaining effect through the rotary digging cast-in-place piles arranged in the superposed triaxial mixing piles. The foundation pit supporting structure formed by the combined construction of the triaxial mixing pile and the rotary excavating cast-in-place pile can ensure the construction quality and reduce the construction cost under the condition of a narrow space.

Compared with the conventional enclosure body structure for stopping water at the outer side and retaining soil at the inner side, the foundation pit supporting structure under the condition of narrow space and the construction method thereof save the land space and fully utilize the underground space.

Compared with a cement-soil composite profile steel/pipe pile enclosure structure adopted under the narrow space condition, the foundation pit supporting structure under the narrow space condition and the construction method thereof provided by the invention have the advantages that the quality is easier to control, the damage to a waterproof curtain is smaller, and the waterproof effect is better.

Compared with an underground continuous wall adopted in a narrow space, the foundation pit supporting structure under the narrow space condition and the construction method thereof greatly save the cost.

Compared with a cement-soil composite cast-in-situ bored pile adopted in a very small space, the foundation pit supporting structure under the narrow space condition and the construction method thereof provided by the invention save the process of mud wall protection and save the cost.

According to the foundation pit supporting structure under the narrow space condition and the construction method thereof, the cement soil generated by rotary excavation can be used for temporary construction of road base layers, earthwork replacement and filling and the like, outward transportation is reduced, the requirement of light weight of garbage in a construction site is met, and cost is saved.

Drawings

FIG. 1 is a schematic view of an elevated structure of a retaining and protecting structure of a foundation pit constructed under narrow space conditions;

FIG. 2 is a schematic structural diagram of a first row of triaxial mixing piles being constructed;

FIG. 3 is a schematic structural view of a second row of triaxial mixing piles being constructed;

FIG. 4 is a schematic structural diagram of construction of a rotary excavating cast-in-place pile in an overlapped triaxial mixing pile;

FIG. 5 is a schematic plan view of a retaining structure for a foundation pit;

FIG. 6 is a schematic elevation view of a retaining structure for a foundation pit;

shown in the figure:

1. the method comprises the following steps of (1) arranging a first row of three-axis mixing piles, 2) arranging a second row of three-axis mixing piles, 3) excavating a cast-in-place pile, 4) existing buildings, 5, protecting pipelines, 6, arranging a three-axis mixing pile machine, and 7) excavating a machine.

Detailed Description

The invention is described in detail below with reference to the attached drawing figures: the advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is provided for the purpose of facilitating and clearly illustrating embodiments of the present invention.

Referring to fig. 1 to 6, an embodiment of the present invention provides a method for constructing a foundation pit supporting structure under a narrow space condition, which includes the following steps:

and 101, constructing a first row of triaxial mixing piles 1 under the condition of a narrow space.

102, after the first row of triaxial mixing piles 1 reach a first preset strength, overlapping and constructing a second row of triaxial mixing piles 2 on one side of the first row of triaxial mixing piles 1 to form overlapped triaxial mixing piles; wherein the first predetermined intensity may be 3 days. In step 101 and step 102, specifically, a three-axis mixing pile can be constructed by using a two-stirring and two-spraying mixing process through the three-axis mixing pile machine 6, and at this time, the sinking and lifting speeds are strictly controlled; the construction is carried out by adopting a sleeve joint hole method, and the construction interval is strictly controlled. Or the cement and the soil can be forcibly stirred in situ at the deep part of the soil layer by the triaxial mixing pile machine 6, and a cement soil consolidation body with certain strength is formed by utilizing the physical and chemical actions between the soil and cement hydrate to form the triaxial mixing pile. And the triaxial mixing pile can be formed by adopting double-shaft co-rotating guniting and soil mixing through the triaxial mixing pile machine 6 and fully stirring and mixing the middle shaft reverse high-pressure air jet in the hole and the cement soil. When the construction intermittence time of the adjacent three-axis stirring piles in the overlapping construction exceeds 24 hours, the sinking and lifting speed is slowed down in the overlapping construction, and the cement mixing amount is correspondingly increased. When the lap joint is poor or can not be lapped, cold joint treatment is carried out, and 3 groups of externally-wrapped cement mixing piles are added.

And 103, constructing the rotary excavating cast-in-place pile 3 along the center of the superposed triaxial mixing pile after the superposed triaxial mixing pile reaches a second preset strength, so that the rotary excavating cast-in-place pile 3 is internally arranged in the superposed triaxial mixing pile to form a foundation pit supporting structure. Wherein the second predetermined intensity may be 28 days. In order to ensure the quality, the single drilling depth is controlled when the cast-in-place pile 3 is constructed by rotary digging; controlling the drilling and lifting speed; and observing the verticality of the drill rod at any time. When the rotary excavating cast-in-place pile 3 is constructed, a spaced pile forming mode can be adopted, and the safe distance between the pile just cast by concrete and the hole forming of the adjacent pile is not less than 4 times of the pile diameter, or the spacing time is not less than 36h. After the hole is formed to the designed elevation, a hole cleaning drill bit is adopted to clean the pile bottom sediment, and the thickness of the pile bottom sediment is ensured to be not more than 200mm; and after the hole is cleaned, immediately putting down the reinforcement cage, reasonably arranging the pouring time of the concrete pump truck, and ensuring that the concrete starts to be poured within 1 hour after the hole is cleaned. In order to improve the quality of the foundation pit supporting structure, the position of the rotary excavating cast-in-place pile 3 needs to be determined, and the central line of the rotary excavating cast-in-place pile 3 is ensured to be parallel and level with the central lines of the three-axis stirring piles 1 and 2. The construction process of the rotary excavating filling pile 3 can be carried out according to the following construction sequence. The pile driver takes place, holes are formed through rotary drilling, the holes are cleaned, the formed holes are detected, a reinforcement cage is hoisted, and concrete is poured. The central line of the built-in rotary digging cast-in-place pile 3 is parallel and level with the central line of the superposed triaxial mixing pile. The built-in rotary digging cast-in-place pile 3 can be constructed after the stacked triaxial mixing pile reaches the age of 28 days. When the rotary excavating filling pile 3 is constructed, a mode of more rotation and less drilling is adopted.

Referring to fig. 1 to 5, in order to improve convenience of construction, in the construction method of the foundation pit supporting structure under the narrow space condition according to the embodiment of the present invention, the first row of triaxial mixing piles 1 is an outer row of triaxial mixing piles, and the second row of triaxial mixing piles 2 is an inner row of triaxial mixing piles. And (3) constructing the inner and outer rows of triaxial mixing piles: digging a groove, positioning a pile driver, testing the pile to determine process parameters, drilling, stirring and forming, and repeatedly constructing; firstly constructing an outer row of three-axis mixing piles 1, and then constructing an inner row of three-axis mixing piles 2; two rows of triaxial mixing piles are mutually occluded, each row of triaxial mixing piles is formed by a plurality of groups of triaxial mixing piles, and a hole is sleeved between adjacent triaxial mixing pile groups in each row of triaxial mixing piles; and immediately constructing the inner row of triaxial mixing piles 2 after the construction of the outer row of triaxial mixing piles 1 is finished. Of course, the first row of triaxial mixing piles 1 is an inner row of triaxial mixing piles, and the second row of triaxial mixing piles 2 is an outer row of triaxial mixing piles.

Referring to fig. 1, 5 and 6, an embodiment of the present invention further provides a foundation pit supporting structure under a narrow space condition, including: overlapping three-axis stirring piles, wherein a first row of three-axis stirring piles 1 and a second row of three-axis stirring piles 2 are overlapped; and the rotary excavating filling pile 3 is arranged in the superposed triaxial stirring pile. Wherein the second row of the triaxial mixing piles 2 can be arranged inside or outside the first row of the triaxial mixing piles 1 in an overlapping manner.

According to the foundation pit supporting structure under the narrow space condition and the construction method thereof, the formed foundation pit supporting structure is adjacent to the existing structure 4 and the protection pipeline 5, wherein the existing structure 4 in the figure 1 comprises but is not limited to a subway air shaft, the protection pipeline 5 comprises but is not limited to a high-voltage wire, a municipal pipe network and the like, a good water stopping effect is achieved through the superposed triaxial mixing piles, and a good soil retaining effect is achieved through the rotary excavating filling pile 3 arranged in the superposed triaxial mixing piles. According to the invention, the foundation pit supporting structure formed by the combined construction of the triaxial mixing pile and the rotary excavating filling pile 3 can ensure the construction quality and reduce the construction cost under the condition of a narrow space. The construction difficulty of the foundation pit supporting structure under the conditions of narrow site and complex surrounding environment is overcome.

Compared with the conventional enclosure body structure for stopping water at the outer side and retaining soil at the inner side, the foundation pit supporting structure under the condition of narrow space and the construction method thereof save the land space and fully utilize the underground space.

Compared with a cement-soil composite profile steel/pipe pile enclosure structure adopted under the narrow space condition, the foundation pit supporting structure under the narrow space condition and the construction method thereof provided by the invention have the advantages that the quality is easier to control, the damage to a waterproof curtain is smaller, and the waterproof effect is better.

Compared with an underground continuous wall adopted in a narrow space, the foundation pit supporting structure under the narrow space condition and the construction method thereof greatly save the cost.

Compared with a cement-soil composite cast-in-situ bored pile adopted in a very small space, the foundation pit supporting structure under the narrow space condition and the construction method thereof provided by the invention save the process of mud wall protection and save the cost.

According to the foundation pit supporting structure and the construction method thereof under the narrow and small space condition, the cement soil generated by rotary excavation can be used for temporary construction of road base layers, earthwork replacement and filling and the like, outward transportation is reduced, the requirement of light weight of garbage in construction sites is met, and cost is saved.

The foundation pit supporting structure and the construction method thereof under the narrow space condition effectively solve the problem that in the engineering construction process, when the distance between the enclosure body and the outer wall of the basement is extremely small and the foundation pit is close to a building, a structure or a pipeline to be protected, the requirements of soil retaining and water stopping can be met in the extremely small space; the construction cost can be controlled; the underground space is fully utilized, and the construction quality is integrally controllable.

The present invention is not limited to the above-described embodiments, and it is apparent that the embodiments described above are some, but not all, of the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention, are within the scope of the invention. Other levels of modification and variation of the present invention may be made by those skilled in the art. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims.

Claims (10)

1. A construction method of a foundation pit supporting structure under the condition of a narrow space is characterized by comprising the following steps:

constructing a first row of triaxial mixing piles under a narrow space condition;

after the first row of triaxial mixing piles reaches a first preset strength, constructing a second row of triaxial mixing piles on one side of the first row of triaxial mixing piles in an overlapping mode to form overlapped triaxial mixing piles;

and after the superposed triaxial mixing pile reaches a second preset strength, constructing a rotary excavating filling pile along the center of the superposed triaxial mixing pile, and arranging the rotary excavating filling pile in the superposed triaxial mixing pile to form a foundation pit supporting structure.

2. The construction method of the foundation pit supporting structure under the narrow space condition according to claim 1, wherein the first row of the triaxial mixing piles is an outer row of the triaxial mixing piles, and the second row of the triaxial mixing piles is an inner row of the triaxial mixing piles.

3. The construction method of the foundation pit supporting structure under the narrow space condition according to claim 1, wherein the first row of the triaxial mixing piles is an inner row of the triaxial mixing piles, and the second row of the triaxial mixing piles is an outer row of the triaxial mixing piles.

4. The method for constructing a foundation pit supporting structure under the narrow space condition according to claim 1, wherein the first predetermined strength is 3 days.

5. The method of claim 1, wherein the second predetermined strength is 28 days.

6. The construction method of the foundation pit supporting structure under the condition of the narrow space according to claim 1, wherein a triaxial mixing pile is constructed by a triaxial mixing pile machine by adopting a two-mixing and two-spraying mixing process.

7. The construction method of a supporting structure for a foundation pit under the condition of a narrow space according to claim 1, wherein cement and soil are forcibly stirred in situ at a deep portion of a soil layer by a triaxial mixing pile machine, and a cement-soil consolidation body having a certain strength is formed to form a triaxial mixing pile by using a physicochemical action between the soil and cement hydrate.

8. The construction method of the foundation pit supporting structure under the narrow space condition according to claim 1, wherein the triaxial mixing pile machine is used for mixing the cement soil by adopting two-axis co-rotating guniting, and the middle-axis reverse high-pressure air injection is fully stirred and mixed with the cement soil in the hole to form the triaxial mixing pile.

9. The utility model provides a supporting construction of foundation ditch under narrow and small space condition which characterized in that includes:

overlapping three-axis stirring piles, wherein a first row of three-axis stirring piles and a second row of three-axis stirring piles are overlapped;

and the rotary excavating cast-in-place pile is arranged in the superposed triaxial stirring pile.

10. The underground excavation supporting structure under narrow and small space condition of claim 9, characterized in that, the coincide of second row of triaxial stirring stake sets up in the inboard or the outside of first row of triaxial stirring stake.

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