CN111576438A - Support system for deep foundation pit and construction method thereof - Google Patents
Support system for deep foundation pit and construction method thereof Download PDFInfo
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- CN111576438A CN111576438A CN202010439895.4A CN202010439895A CN111576438A CN 111576438 A CN111576438 A CN 111576438A CN 202010439895 A CN202010439895 A CN 202010439895A CN 111576438 A CN111576438 A CN 111576438A
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D17/00—Excavations; Bordering of excavations; Making embankments
- E02D17/02—Foundation pits
- E02D17/04—Bordering surfacing or stiffening the sides of foundation pits
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Abstract
The invention discloses a supporting system of a deep foundation pit and a construction method thereof, wherein the supporting system comprises at least two circles of supporting structures arranged along the side wall of the foundation pit and an in-pit reinforcing structure arranged along the innermost circle of the supporting structures, the supporting structures comprise a plurality of cast-in-place piles, and each cast-in-place pile in the supporting structures is arranged along the side wall of the foundation pit; the pit internal reinforcing structure comprises a plurality of back pressure soil isolation piers and/or pit internal back pressure soil. The supporting structure arranged in the supporting system plays a role in supporting and blocking and guaranteeing stability of the foundation pit, the back pressure soil isolation piers play a role in shortening the length of the supporting structure and prolonging the length of the supporting structure, rigidity of the crown beam is improved, and the pit bottom back pressure soil is used for reinforcing or replacing a pit bottom supporting system, so that the purposes of controlling or reducing displacement of the supporting structure, reducing the embedding depth of the supporting structure, saving construction cost and the like are achieved. The invention can be widely applied to the technical field of deep foundation pit construction.
Description
Technical Field
The invention relates to the technical field of deep foundation pit construction, in particular to a supporting system of a deep foundation pit and a construction method thereof.
Background
Aiming at a deep foundation pit (at least two layers of basements) with a super-large plane size (the unilateral length exceeds 500m) and deep soft soil (the soft soil thickness is larger than 30m), the foundation pit supporting scheme adopted at present comprises cast-in-place piles (or underground diaphragm walls) + enlarged head anchor cables, cast-in-place piles (or underground diaphragm walls) + inclined struts, double-row pile structures and the like.
The scheme-cast-in-place pile (or underground diaphragm wall) + the expanded head anchor cable is limited in that the expanded head anchor cable is only suitable for areas where the anchor cable is allowed to be driven in the surrounding environment, and the defect is that the tension of the expanded head anchor cable is easy to loosen, so that the displacement of a supporting structure is overlarge. The defects exist because the anchor cable is easy to loose due to the creep property because the soft soil layer is thick and the enlarged head part of the anchor cable is still in the soft soil layer.
The limitation of the scheme II that the cast-in-place pile (or the diaphragm wall) and the inclined strut are only suitable for construction scenes that the middle area can be excavated and the bottom plate can be constructed first and then the inclined strut is supported on the bottom plate. The defects are that the earthwork and the bottom plate in the middle area need to be constructed firstly, the inclined strut is supported on the bottom plate, the soft soil of the soil in the pit below the inclined strut needs to be reinforced in advance, and the cost is high.
The three-row and two-row pile of the scheme belongs to a cantilever type supporting structure, and has the defect that the displacement of the two-row pile is also large due to the fact that the plane size of a foundation pit is large and the rigidity of a top beam of the two-row pile is small.
Disclosure of Invention
In order to solve at least one of the technical problems and reinforce the support, the invention provides a support system of a deep foundation pit and a construction method thereof, and the adopted technical scheme is as follows:
the support system of the deep foundation pit comprises at least two circles of support structures arranged along the side wall of the foundation pit and an in-pit reinforcing structure arranged along the innermost circle of the support structures, wherein each support structure comprises a plurality of cast-in-place piles, and each cast-in-place pile in each support structure is arranged along the side wall of the foundation pit; the pit internal reinforcing structure comprises a plurality of back pressure soil isolation piers and/or pit internal back pressure soil.
In some embodiments of the invention, the in-pit reinforcing structure comprises pit bottom reinforced soil.
In some embodiments of the invention, intermediate reinforced soil is filled between two adjacent circles of the supporting structures.
In some embodiments of the invention, a pile top connecting plate is arranged on the top of the supporting structure.
In some embodiments of the invention, the pile top connecting plate is mainly made of reinforced concrete.
In some embodiments of the invention, the number of the supporting structures is three, and the in-pit reinforcing structure comprises in-pit return soil.
The construction method of the support system provided by the invention comprises the following construction steps: a-1, leveling a field, and constructing a reinforced stirring pile, a soil-back-pressure partition stirring pile and a stirring pile in the middle of a double-row pile structure in a foundation pit; a-2, constructing double rows of cast-in-place piles; a-3, excavating a groove to the top surface of the double-row pile structure, and constructing a pile top connecting plate on the top surface of the double-row structure; a-4, excavating counter-pressure soil in a pit influencing construction step by step; a-5, reserving back pressure soil isolation piers, excavating back pressure soil above the bottom of a foundation pit between the back pressure soil isolation piers, constructing and excavating a basement structure in a back pressure soil area, and backfilling the side wall of the foundation pit in the area where the basement structure construction is completed; a-6, excavating the soil back-pressure partition piers, constructing a basement structure in the soil back-pressure partition pier region, and backfilling the side wall of the foundation pit.
In some embodiments of the invention, in A-5, the back pressure soil and the back pressure soil isolation piers in the pit are reserved, construction is carried out according to the width and the height of a back pressure soil platform required by design, the back pressure soil influencing the construction is excavated in a step-by-step excavation mode, the exterior is excavated, pile foundation detection is carried out, and finally earthwork close to a supporting structure is excavated.
In some embodiments of the invention, in the step A-5, the outer side area far away from the cast-in-place pile is divided into regions, layers and blocks to be excavated to the bottom of the foundation pit, and the basement structure of the earth excavation area is constructed.
The embodiment of the invention at least has the following beneficial effects: the supporting structure arranged in the supporting system plays a role in supporting and blocking and guaranteeing stability of the foundation pit, the back pressure soil isolation piers play a role in shortening the length of the supporting structure and prolonging the length of the supporting structure, rigidity of the crown beam is improved, and the pit bottom back pressure soil is used for reinforcing or replacing a pit bottom supporting system, so that the purposes of controlling or reducing displacement of the supporting structure, reducing the embedding depth of the supporting structure, saving construction cost and the like are achieved. The invention can be widely applied to the technical field of deep foundation pit construction.
Drawings
FIG. 1 shows a supporting system consisting of a double row pile structure and a back pressure soil isolation pier;
FIG. 2 is a supporting system consisting of three rows of pile structures and pit soil;
FIG. 3 is a cross-sectional view 3-3 of the structure of FIG. 2;
FIG. 4 is a supporting system consisting of a double-row pile structure, back pressure soil isolation piers and pit back pressure soil;
FIG. 5 is a cross-sectional view 1-1 of the structure of FIG. 4;
fig. 6 is a cross-sectional view 2-2 of the structure of fig. 4.
Detailed Description
The present invention will be further described with reference to fig. 1 to 6.
The invention relates to a supporting system of a deep foundation pit, which can provide a supporting scheme with reliable stress and convenient construction for the deep foundation pit of deep soft soil with an oversized plane size, and can solve the risk of overlarge foundation pit displacement caused by small horizontal rigidity of a conventional double-row pile supporting structure on the surface. The supporting system does not need special construction mechanical equipment, can be solved by a conventional construction scheme, and has the advantages of clear supporting stress, easiness in operation and implementation, easiness in construction quality guarantee and the like.
The supporting system comprises at least two circles of supporting structures arranged along the side wall of the foundation pit and an in-pit reinforcing structure arranged along the innermost circle of the supporting structures, and the supporting structures play a role in supporting and blocking and guarantee the stability of the foundation pit. The supporting structure comprises a plurality of cast-in-place piles 11, and each cast-in-place pile 11 in the supporting structure is arranged along the side wall of the foundation pit to form a row of supporting piles. The pit internal reinforcing structure comprises a plurality of back pressure soil isolation piers 12 and/or pit internal back pressure soil 13, and supports the inner ring cast-in-place pile 11 in the foundation pit. The back pressure soil isolation pier 12 shortens the length of the extended section of the supporting structure, namely, the length along the side length of the support is reduced, so that the rigidity of the crown beam is improved, the construction of the mixing pile is generally required, and particularly when the construction of a triaxial mixing pile is adopted, the quality is easily ensured. The pit back pressure soil 13 is used for reinforcing or replacing a pit bottom supporting system, so that the purposes of controlling or reducing the displacement and the internal force of a supporting structure, reducing the embedding depth of the supporting structure and saving the construction cost are achieved, and the construction can be realized by adopting a stirring pile construction mode or a mode of retaining an original boss.
In some embodiments of the present invention, the number of the supporting structures is two, the two layers of supporting structures form a double-row pile structure, the in-pit reinforcing structure includes a plurality of soil-back pressure piers 12, each soil-back pressure pier 12 is distributed at intervals along the supporting structure of the inner layer and is used for supporting and reinforcing the inner side of the double-row pile structure, and the inner side is referred to as one side in the pit. The problem that the double-row pile supporting structure in the prior art is excessively large in displacement in a deep foundation pit of deep soft soil with an oversized plane size is effectively solved, the horizontal rigidity is improved by shortening the length of the double-row pile supporting extension section, namely, the supporting length is shortened by adopting the back pressure soil partition pier 12 reinforced by the cement mixing piles on the inner side of the foundation pit, and the horizontal rigidity of the double-row pile crown beam is improved by utilizing the space effect of the foundation pit. In addition, the earth-pressure-resisting piers 12 can also be used as an earth-discharging passage.
In some embodiments of the present invention, the number of the supporting structures is two, the two layers of supporting structures form a double-row pile structure, the in-pit reinforcing structure includes a plurality of anti-pressure soil piers 12 and in-pit anti-pressure soil 13, each anti-pressure soil pier 12 is distributed at intervals along the supporting structure of the inner layer, and the in-pit anti-pressure soil 13 is filled between two adjacent anti-pressure soil piers 12 and is used for supporting and reinforcing the inner side of the double-row pile structure.
In some embodiments of the invention, the number of supporting structures is arranged in three layers, the three layers of supporting structures constitute a three-row pile structure, and the in-pit reinforcing structure comprises in-pit counter-pressure soil 13 for supporting and reinforcing the inner side of the three-row pile structure. Under the condition that the total pile number is not changed, the distance between the double rows of piles is enlarged to form a three-row pile structure, so that the lateral stiffness of the double rows of piles is improved. And the pit is internally reinforced, and the bottom of the pit is covered with counter-pressure soil, so that the lateral stiffness is improved.
In some embodiments of the invention, the in-pit reinforcing structure comprises pit bottom reinforcing soil 15, and the in-pit reinforcing structure is used for reinforcing the pit and improving the lateral stiffness. The pit bottom reinforcement can improve the mechanical property of the soil layer of the passive area of the support system and improve the strength and rigidity of the soil layer of the pit bottom, so that the lateral resistance of the soil body of the passive area is improved, the horizontal displacement and deformation of the support structure are further controlled, and the construction of the mixing pile is generally required.
In some embodiments of the present invention, intermediate reinforced soil is filled between two adjacent circles of supporting structures. Further, a pile top connecting plate 14 is arranged at the top of the supporting structure, and the function of increasing the lateral stiffness of the crown beam is achieved. In particular, the pile top connecting plate 14 is mainly composed of reinforced concrete. The side stiffness of the double-row pile structure or the three-row pile structure is improved by adopting a thick plate connecting mode on the pile top.
The invention relates to a construction method of a supporting system, which takes the construction of a double-row pile structure as an example for explanation. The construction method comprises the following construction steps: a-1, leveling a field, and constructing a reinforced stirring pile, a soil-back-pressure partition stirring pile and a stirring pile in the middle of a double-row pile structure in a foundation pit; a-2, constructing double rows of cast-in-place piles; a-3, excavating a groove to the top surface of the double-row pile structure, and constructing pile top connecting plates 14 on the top surface of the double-row pile structure; a-4, excavating back pressure soil 13 in the pit influencing construction step by step; a-5, reserving back pressure soil isolation piers 12, excavating back pressure soil above the bottom of a foundation pit between the back pressure soil isolation piers 12, constructing and excavating a basement structure in a back pressure soil area, and backfilling the side wall of the foundation pit in the area where the basement structure construction is completed; a-6, excavating the back pressure soil isolation pier 12, constructing a basement structure in the area of the back pressure soil isolation pier 12, and backfilling the side wall of the foundation pit.
And A-5, retaining the back pressure soil 13 and the back pressure soil partition piers 12 in the pit, constructing according to the width and the height of a back pressure soil platform required by design, excavating the outside and detecting pile foundations in a step-by-step excavation mode on the back pressure soil influencing the construction, and finally excavating the earthwork close to the supporting structure. Furthermore, the outer side area far away from the cast-in-place pile 11 is excavated to the bottom of the foundation pit in a partitioning, layering and partitioning mode, namely basin-type excavation construction is adopted to the bottom of the foundation pit, and the basement structure of the earth excavation area is constructed, namely the basement structure is excavated in the center area of the foundation pit.
While the embodiments of the present invention have been described in detail with reference to the drawings, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art.
Claims (9)
1. The utility model provides a support system of deep basal pit which characterized in that: comprises that
The supporting structure comprises a plurality of cast-in-place piles (11), and each cast-in-place pile (11) in the supporting structure is arranged along the side wall of the foundation pit;
and the pit internal reinforcing structure is arranged along the innermost ring of the supporting structure and comprises a plurality of back pressure soil piers (12) and/or pit internal back pressure soil (13).
2. The support system for a deep foundation pit according to claim 1, wherein: the in-pit reinforcing structure comprises pit bottom reinforcing soil (15).
3. The support system for a deep foundation pit according to claim 1, wherein: and middle reinforced soil is filled between every two adjacent circles of the supporting structures.
4. The support system for a deep foundation pit according to claim 1, wherein: and a pile top connecting plate (14) is arranged at the top of the supporting structure.
5. The support system for a deep foundation pit according to claim 4, wherein: the pile top connecting plate (14) is mainly made of reinforced concrete.
6. The support system for a deep foundation pit according to claim 1, wherein: the number of the supporting structures is three, and the pit reinforcing structure comprises pit counter-pressure soil (13).
7. The construction method of the support system is characterized by comprising the following construction steps:
a-1, leveling a field, and constructing a reinforced stirring pile, a soil-back-pressure partition stirring pile and a stirring pile in the middle of a double-row pile structure in a foundation pit;
a-2, constructing double rows of cast-in-place piles;
a-3, excavating a groove to the top surface of the double-row pile structure, and constructing a pile top connecting plate (14) on the top surface of the double-row structure;
a-4, excavating pit counter-pressure soil (13) influencing construction step by step;
a-5, reserving back pressure soil isolation piers (12), excavating back pressure soil above the bottom of a foundation pit between the back pressure soil isolation piers (12), constructing a basement structure of an excavated back pressure soil area, and backfilling the side wall of the foundation pit in the area where the basement structure construction is completed;
a-6, excavating the back pressure soil isolation pier (12), constructing a basement structure in the area of the back pressure soil isolation pier (12), and backfilling the side wall of the foundation pit.
8. The construction method of a support system according to claim 7, characterized in that: and A-5, reserving the back pressure soil (13) and the back pressure soil partition piers (12) in the pit, constructing according to the width and the height of a back pressure soil platform required by design, excavating the outside and well detecting a pile foundation firstly by adopting a step-by-step excavation mode on the back pressure soil influencing the construction, and finally excavating earthwork close to a supporting structure.
9. The construction method of a support system according to claim 8, characterized in that: in A-5, the outer side area far away from the cast-in-place pile (11) is divided into regions, layers and blocks to be excavated to the bottom of the foundation pit, and a basement structure of the earth excavation area is constructed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010439895.4A CN111576438A (en) | 2020-05-22 | 2020-05-22 | Support system for deep foundation pit and construction method thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010439895.4A CN111576438A (en) | 2020-05-22 | 2020-05-22 | Support system for deep foundation pit and construction method thereof |
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| CN111576438A true CN111576438A (en) | 2020-08-25 |
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| CN202010439895.4A Pending CN111576438A (en) | 2020-05-22 | 2020-05-22 | Support system for deep foundation pit and construction method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113445515A (en) * | 2021-07-23 | 2021-09-28 | 中国建筑第二工程局有限公司 | Construction method for reverse construction of three-row pile support of ultra-deep foundation pit |
| CN113846653A (en) * | 2021-11-17 | 2021-12-28 | 广州市市政工程试验检测有限公司 | Prefabricated test block back-pressure foundation pit supporting system and construction method |
-
2020
- 2020-05-22 CN CN202010439895.4A patent/CN111576438A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113445515A (en) * | 2021-07-23 | 2021-09-28 | 中国建筑第二工程局有限公司 | Construction method for reverse construction of three-row pile support of ultra-deep foundation pit |
| CN113445515B (en) * | 2021-07-23 | 2022-08-23 | 中国建筑第二工程局有限公司 | Construction method for reverse construction of three-row pile support of ultra-deep foundation pit |
| CN113846653A (en) * | 2021-11-17 | 2021-12-28 | 广州市市政工程试验检测有限公司 | Prefabricated test block back-pressure foundation pit supporting system and construction method |
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