CN111877366A - Combined type foundation pit supporting structure and construction method thereof - Google Patents

Combined type foundation pit supporting structure and construction method thereof Download PDF

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Publication number
CN111877366A
CN111877366A CN202010923882.4A CN202010923882A CN111877366A CN 111877366 A CN111877366 A CN 111877366A CN 202010923882 A CN202010923882 A CN 202010923882A CN 111877366 A CN111877366 A CN 111877366A
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CN
China
Prior art keywords
foundation pit
cement
mixing pile
soil mixing
rib body
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Pending
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CN202010923882.4A
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Chinese (zh)
Inventor
马斌
罗如平
万宗江
朱碧堂
陈晓飞
丁志文
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East China Jiaotong University
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East China Jiaotong University
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Priority to CN202010923882.4A priority Critical patent/CN111877366A/en
Publication of CN111877366A publication Critical patent/CN111877366A/en
Pending legal-status Critical Current

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    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D17/00Excavations; Bordering of excavations; Making embankments
    • E02D17/02Foundation pits
    • E02D17/04Bordering surfacing or stiffening the sides of foundation pits
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2600/00Miscellaneous
    • E02D2600/30Miscellaneous comprising anchoring details

Abstract

The invention discloses a combined type foundation pit supporting structure and a construction method thereof, and belongs to the technical field of civil engineering. The foundation pit supporting structure comprises a cement mixing pile and is arranged on the outer side of an excavation surface of a foundation pit; the reinforcement body is arranged between the excavation surface of the foundation pit and the cement-soil mixing pile, one end of the reinforcement body is anchored in the cement-soil mixing pile, and the other end of the reinforcement body is anchored on the excavation surface of the foundation pit; the reinforcing mesh is arranged on the excavation surface of the foundation pit, and the end part of the rib body, which is positioned on the excavation surface of the foundation pit, is connected with the reinforcing mesh through a reinforcing rib; and the concrete layer is positioned on the surface of the steel bar net piece. The invention also discloses a construction method of the combined type foundation pit supporting structure, the foundation pit supporting structure can give full play to the strength characteristic of the waterproof curtain of the cement soil mixing pile while resisting water and preventing water, and the anchoring effect is more reliable. More importantly, due to the good anchoring effect of the cement-soil mixing pile, the length of the rib body material can be greatly reduced, and the rib body material is limited from the excavation surface of the foundation pit to the cement-soil mixing pile.

Description

Combined type foundation pit supporting structure and construction method thereof
Technical Field
The invention relates to the technical field of civil engineering, in particular to a combined type foundation pit supporting structure and a construction method thereof.
Background
In the design of a foundation pit support of a water-rich stratum, a cement-soil mixing pile is usually used as a waterproof curtain to isolate the communication of underground water inside and outside a foundation pit so as to facilitate the excavation construction of the foundation pit. In fact, besides the water-resisting function, the cement-soil mixing pile has excellent mechanical properties, and especially in sandy soil stratum, the unconfined compressive strength of the cement-soil mixing pile is generally close to 4MPa and far exceeds that of natural soil. Therefore, in the current foundation pit support design, the high bearing characteristics of the cement-soil mixing piles are not fully exerted only by utilizing the water-resisting performance of the cement-soil mixing piles, and the waste of materials or structures is caused, which is a pity.
Chinese patent document CN206599785U discloses a row pile anchored cement-soil pile continuous wall supporting structure, wherein the excavation surface of the foundation pit is supported by vertical row piles and a concrete surface layer, and anchored to the outside cement-soil mixing pile through a full-length bonding anchor rod, thereby forming an integrally stressed foundation pit excavation supporting structure. However, in the method, a corresponding pile arrangement structure needs to be arranged on the excavation surface, and the cement soil mixing piles need to be additionally and independently arranged, so that the strength characteristic of the waterproof curtain is not fully utilized, and the construction cost is still high.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provides a foundation pit supporting structure and a construction method thereof, wherein the self strength of a waterproof curtain of a cement-soil mixing pile in a water-rich stratum can be fully utilized.
The invention provides a combined type foundation pit supporting structure and a construction method thereof, wherein the combined type foundation pit supporting structure comprises the following steps:
the cement soil mixing pile is arranged on the outer side of the excavation surface of the foundation pit;
the number of the rib bodies is multiple, the rib bodies are uniformly arranged between the excavation surface of the foundation pit and the cement soil mixing piles in multiple rows, one end of each rib body is anchored in the cement soil mixing pile, and the other end of each rib body is anchored on the excavation surface of the foundation pit;
the reinforcing mesh is arranged on the excavation surface of the foundation pit, and the end part of the rib body, which is positioned on the excavation surface of the foundation pit, is connected with the reinforcing mesh through a reinforcing rib;
and the concrete layer is positioned on the surface of the steel mesh.
Preferably, the end part of the rib body is fixedly connected with the reinforcing rib and the reinforcing mesh in a bolt connection or welding mode.
Preferably, the rib body is obliquely arranged between the cement soil mixing pile and the excavation surface of the foundation pit, the inclination angle is 5-30 degrees, the high end of the rib body is positioned on the excavation surface of the foundation pit, and the low end of the rib body is positioned on the cement soil mixing pile.
Preferably, the tendon is a tensile tendon or a non-tensile tendon.
Preferably, the thickness of the single cement mixing pile is not less than 1 m.
Preferably, when the excavation depth is more than 8 meters, arranging a plurality of cement soil mixing piles; when the rib body is a tensile rib body, the rib body is anchored in the cement mixing pile at the outermost side; when the rib body is a non-tension type rib body, the rib body is anchored in the cement-soil mixing pile at the outermost side or the cement-soil mixing pile at the inner side.
The invention also discloses a construction method of the combined type foundation pit supporting structure, which comprises the following steps:
s101, constructing cement soil mixing piles at the design positions on the outer side of the excavation surface of the foundation pit, and reliably overlapping the cement soil mixing piles to form a continuous waterproof curtain;
s102, excavating a foundation pit after the cement soil mixing pile reaches the design strength, and constructing a first row of drilled holes when the first row of reinforcement bodies are excavated to be 0.5m below the design position, wherein the length of the drilled holes penetrating through the cement soil mixing pile is not less than 1m, and the inclination angle of the drilled holes is 5-30 degrees;
s103, inserting a rib body into the drill hole, and grouting the drill hole;
s104, laying a reinforcing mesh at the excavation surface of the foundation pit, and then reliably connecting the end part of the rib body to the reinforcing mesh through transverse and longitudinal reinforcing ribs to form a stressed whole;
s105, after the connection of the reinforcement body material and the reinforcing mesh is completed, spraying concrete on the excavation surface to complete the construction of the cement-soil mixing pile and reinforcement body material combined type foundation pit supporting structure;
when the rib body is a prestressed anchor cable, the rib body material is additionally prestressed and anchored on the sprayed concrete surface layer.
When the rib body is a non-tension type rib body such as a soil nail and an anchor rod, full-length grouting is needed, and when the rib body is a tension type rib body such as a prestressed anchor cable, grouting is only carried out in the range of the cement mixing pile.
Compared with the prior art, the invention has the beneficial effects that: the foundation pit supporting structure can give full play to the strength characteristic of the waterproof curtain of the cement soil mixing pile while resisting water and preventing water, and the anchoring effect is more reliable. More importantly, due to the good anchoring effect of the cement-soil mixing pile, the length of the rib body material can be greatly reduced, and the rib body material is limited from the excavation surface of the foundation pit to the cement-soil mixing pile. Under the large environment of strict site red line control, the supporting construction method can exert the supporting performance of rib materials such as soil nails, anchor rods, prestressed anchor cables and the like to the maximum extent, and the application range of the site is expanded.
Drawings
FIG. 1 is a cross-sectional view of a single cement mixing pile foundation pit support of the present invention;
FIG. 2 is a cross-sectional view of a multi-course cemented soil mixing pile foundation pit support of the present invention;
fig. 3 is a detailed view of the shotcrete face layer construction of the present invention.
Description of reference numerals:
1. the concrete mixing pile comprises a cement mixing pile body, a rib body, a reinforcing steel mesh piece, a reinforcing rib, a concrete layer and a stretchable rib body, wherein the reinforcing steel mesh piece is arranged at the bottom of the cement mixing pile body, the reinforcing steel mesh piece is arranged at the top of the cement mixing pile body, the reinforcing steel mesh piece is arranged at the bottom of the cement mixing.
Detailed Description
Detailed description of the preferred embodimentsthe following detailed description of the present invention will be made with reference to the accompanying drawings 1-3, although it should be understood that the scope of the present invention is not limited to the specific embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The invention provides a combined type foundation pit supporting structure and a construction method thereof, wherein the combined type foundation pit supporting structure comprises the following steps:
the cement soil mixing pile 1 is arranged on the outer side of the excavation surface of the foundation pit;
the number of the rib bodies 2 is multiple, the rib bodies are uniformly arranged between the excavation surface of the foundation pit and the cement soil mixing pile 1 in multiple rows, one end of each rib body 2 is anchored in the cement soil mixing pile, and the other end of each rib body is anchored on the excavation surface of the foundation pit;
the reinforcing mesh 3 is arranged on the excavation surface of the foundation pit, and the end part of the rib body 2, which is positioned on the excavation surface of the foundation pit, is connected with the reinforcing mesh 3 through a reinforcing rib 4;
and the concrete layer 5 is positioned on the surface of the steel mesh 3.
Wherein, the end of the rib body 2 is fixedly connected with the reinforcing rib 4 and the reinforcing mesh 3 by adopting a bolt connection or welding mode.
The rib body 2 is obliquely arranged between the cement soil mixing pile 1 and the foundation pit excavation surface, the inclination angle is 5-30 degrees, the high end of the rib body 2 is located on the foundation pit excavation surface, and the low end of the rib body is located on the cement soil mixing pile 1.
Wherein, the rib body 2 is a stretching rib body or a non-stretching rib body.
Wherein, the thickness of the single cement mixing pile is not less than 1 m.
When the excavation depth is more than 8m, arranging a plurality of cement soil mixing piles; when the rib body 2 is a tensile rib body, the rib body is anchored in the cement mixing pile at the outermost side; when the rib body 2 is a non-tension type rib body, the rib body is anchored in the outermost cement mixing pile or the inner cement mixing pile.
When the pile body is a multi-channel pile body, a single non-stretching rib body 2 or a single stretching rib body 6 can be adopted, and the two can also be combined for use. The concrete use or combination mode of the method needs to comprehensively consider indexes such as excavation depth of the foundation pit, construction cost, deformation control requirements and the like and is determined through corresponding design calculation.
As shown in fig. 1 to 3, the combined foundation pit supporting structure of the cement mixing pile and the reinforcement material provided by the invention comprises a sprayed concrete layer 5, a reinforcement 2 and a cement mixing pile 1. The cement-soil mixing pile 1 is arranged on the outer side of the excavation surface of the foundation pit within a certain distance range, one end of the rib body 2 is anchored in the cement-soil mixing pile 1, and the other end of the rib body is anchored on a sprayed concrete layer 5 on the excavation surface. Generally, when the excavation depth is smaller than 8m, only one cement mixing pile can be used, as shown in fig. 1. At the moment, the rib body material can adopt materials such as soil nails, anchor rods and the like. When the excavation depth of the foundation pit is further increased, a plurality of cement mixing piles may be used, as shown in fig. 2. At this time, the rib body can be a non-stretching rib body 2 such as a soil nail and an anchor rod, and can also be a stretching rib body 6 such as a prestressed anchor cable, so as to further increase the constraint effect of the cement mixing pile on the sprayed concrete surface layer 5.
The spraying surface layer comprises a steel bar net piece 3 and a concrete layer 5, the rib body 2 is reliably connected to the steel bar net piece 3 through transverse and longitudinal reinforcing ribs 4, and then the concrete is sprayed to form an integral stressed structure.
The construction method of the combined type foundation pit supporting structure comprises the following steps:
s101, constructing cement soil mixing piles at the design positions on the outer side of the excavation surface of the foundation pit, and reliably overlapping the cement soil mixing piles to form a continuous waterproof curtain;
s102, excavating a foundation pit after the cement soil mixing pile reaches the design strength, and constructing a first row of drilled holes when the first row of reinforcement bodies are excavated to be 0.5m below the design position, wherein the length of the drilled holes penetrating through the cement soil mixing pile is not less than 1m, and the inclination angle of the drilled holes is 5-30 degrees;
s103, inserting rib body materials into the drill hole, and grouting the drill hole; the soil nail and the anchor rod type rib body need full-length grouting, and the prestressed anchor cable type rib body only needs grouting in the range of the cement soil mixing pile; constructing each row of the reinforcement bodies according to the same flow;
s104, laying a reinforcing mesh at the excavation surface of the foundation pit, and then reliably connecting the outer end of the reinforcement material to the reinforcing mesh through transverse and longitudinal reinforcing ribs to form a stressed whole, wherein the connection mode is preferably welding or bolt connection;
and S105, after the connection of the rib body material and the reinforcing mesh is finished, spraying concrete on the excavated surface to finish the construction of the cement mixing pile and rib body material combined type foundation pit supporting structure, and when the rib body material is a prestressed anchor cable, additionally applying prestress to the rib body material and anchoring the rib body material on the sprayed concrete surface layer.
When the rib body is a non-tension type rib body such as a soil nail and an anchor rod, full-length grouting is needed, and when the rib body is a tension type rib body such as a prestressed anchor cable, grouting is only carried out in the range of the cement mixing pile.
In a word, the construction of the invention is simple and convenient, does not need large-scale complicated mechanical equipment, and compared with other foundation pit supporting construction methods, the invention has lower cost and obvious economic benefit because the self high-strength characteristic of the existing waterproof curtain structure is fully utilized and other supporting and stopping structures are not needed to be additionally arranged. In addition, because the length of the rib material in the supporting structure is short, the red line of the surrounding buildings cannot be invaded, and therefore the field application range of the rib material such as soil nails, anchor rods, prestressed anchor cables and the like can be greatly expanded.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (8)

1. A modular excavation supporting construction, its characterized in that includes:
the cement soil mixing pile (1) is arranged on the outer side of the excavation surface of the foundation pit;
the number of the rib bodies (2) is multiple, the rib bodies are uniformly arranged between the excavation surface of the foundation pit and the cement soil mixing pile (1) in multiple rows, one end of each rib body (2) is anchored in the cement soil mixing pile, and the other end of each rib body is anchored on the excavation surface of the foundation pit;
the reinforcing steel bar net piece (3) is arranged on the excavation surface of the foundation pit, and the end part of the rib body (2) positioned on the excavation surface of the foundation pit is connected with the reinforcing steel bar net piece (3) through a reinforcing rib (4);
and the concrete layer (5) is positioned on the surface of the steel mesh (3).
2. The combined foundation pit supporting structure according to claim 1, wherein the end of the reinforcement body (2) is fixedly connected with the reinforcing rib (4) and the reinforcing mesh (3) by bolts or welding.
3. The combined foundation pit supporting structure according to claim 1, wherein the reinforcement body (2) is obliquely arranged between the cement-soil mixing pile (1) and the excavation surface of the foundation pit, the inclination angle is 5-30 degrees, and the high end of the reinforcement body (2) is positioned on the excavation surface of the foundation pit and the low end is positioned on the cement-soil mixing pile (1).
4. The modular foundation pit supporting structure according to claim 1, wherein the tendon body (2) is a tension tendon body or a non-tension tendon body.
5. The modular foundation pit supporting structure of claim 4, wherein the thickness of the single cement-soil mixing pile is not less than 1 m.
6. The combined foundation pit supporting structure of claim 5, wherein when the excavation depth is more than 8m, a plurality of cement-soil mixing piles are arranged; when the rib body (2) is a tensile rib body, the rib body is anchored in the cement mixing pile at the outermost side; when the rib body (2) is a non-tension type rib body, the rib body is anchored in the cement-soil mixing pile at the outermost side or the cement-soil mixing pile at the inner side.
7. The construction method of a modular foundation pit supporting structure according to any one of claims 1 to 6, comprising the steps of:
s101, constructing cement soil mixing piles at the design positions on the outer side of the excavation surface of the foundation pit, and reliably overlapping the cement soil mixing piles to form a continuous waterproof curtain;
s102, excavating a foundation pit after the cement soil mixing pile reaches the design strength, and constructing a first row of drilled holes when the first row of reinforcement bodies are excavated to be 0.5m below the design position, wherein the length of the drilled holes penetrating through the cement soil mixing pile is not less than 1m, and the inclination angle of the drilled holes is 5-30 degrees;
s103, inserting a rib body into the drill hole, and grouting the drill hole;
s104, laying a reinforcing mesh at the excavation surface of the foundation pit, and then reliably connecting the end part of the rib body to the reinforcing mesh through transverse and longitudinal reinforcing ribs to form a stressed whole;
s105, after the connection of the reinforcement body material and the reinforcing mesh is completed, spraying concrete on the excavation surface to complete the construction of the cement-soil mixing pile and reinforcement body material combined type foundation pit supporting structure;
when the rib body is a prestressed anchor cable, the rib body material is additionally prestressed and anchored on the sprayed concrete surface layer.
8. The construction method of a combined type foundation pit supporting structure according to claim 7, wherein when the rib body is a non-tension type rib body such as a soil nail and an anchor rod, full-length grouting is required, and when the rib body is a tension type rib body such as a prestressed anchor cable, grouting is only performed in the range of the cement soil mixing pile.
CN202010923882.4A 2020-09-04 2020-09-04 Combined type foundation pit supporting structure and construction method thereof Pending CN111877366A (en)

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Application Number Priority Date Filing Date Title
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114809022A (en) * 2022-06-12 2022-07-29 陕西省外经贸实业集团建设工程有限公司 Deep foundation pit flexible supporting method based on one-way rib beam structure
CN114960677A (en) * 2022-06-17 2022-08-30 广东省铁路规划设计研究院有限公司 Anchor-pulling combined type foundation pit supporting structure suitable for soft soil area and construction method thereof
CN115341551A (en) * 2022-08-05 2022-11-15 中建一局集团第二建筑有限公司 Composite soil nail supporting structure for limited soil body and construction method thereof

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114809022A (en) * 2022-06-12 2022-07-29 陕西省外经贸实业集团建设工程有限公司 Deep foundation pit flexible supporting method based on one-way rib beam structure
CN114960677A (en) * 2022-06-17 2022-08-30 广东省铁路规划设计研究院有限公司 Anchor-pulling combined type foundation pit supporting structure suitable for soft soil area and construction method thereof
CN115341551A (en) * 2022-08-05 2022-11-15 中建一局集团第二建筑有限公司 Composite soil nail supporting structure for limited soil body and construction method thereof
CN115341551B (en) * 2022-08-05 2023-07-04 中建一局集团第二建筑有限公司 Composite soil nail supporting structure for limited soil body and construction method thereof

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