CN112695765A - Steel support construction method for foundation pit enclosure structure of open cut section of subway station - Google Patents
Steel support construction method for foundation pit enclosure structure of open cut section of subway station Download PDFInfo
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- CN112695765A CN112695765A CN202011430076.XA CN202011430076A CN112695765A CN 112695765 A CN112695765 A CN 112695765A CN 202011430076 A CN202011430076 A CN 202011430076A CN 112695765 A CN112695765 A CN 112695765A
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- steel
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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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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D2250/00—Production methods
- E02D2250/0046—Production methods using prestressing techniques
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D2300/00—Materials
- E02D2300/0026—Metals
- E02D2300/0029—Steel; Iron
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- General Engineering & Computer Science (AREA)
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Abstract
The invention discloses a steel support construction method of a foundation pit support structure of an open cut area of a subway station, which comprises the steps of respectively installing steel purlins at positions corresponding to two ends of a steel support to be installed on the foundation pit support structure; hoisting the prefabricated steel support into a foundation pit, and respectively connecting and supporting two ends of the steel support on the steel purlin; installing a movable head for pressurizing between the end part of the steel support and the building enclosure, applying prestress by adopting a mode that the movable head is driven by a jack to pressurize successively twice, wherein the pressure for applying the prestress for the first time is 70-80% of the designed pre-axial force, the pressure for applying the prestress for the second time is 104-106% of the designed pre-axial force, and then locking and fixing the movable head; and arranging an anti-falling device for preventing the steel support from falling between the steel support and the building envelope. The steel support construction method has the advantages of simple process, easiness in implementation, high safety, capability of improving the stability and reliability of the support and the like.
Description
Technical Field
The invention relates to the technical field of subway construction, in particular to a steel support construction method for a foundation pit enclosure structure of an open cut area of a subway station.
Background
In the process of foundation pit construction of a subway station, a building enclosure needs to be constructed in time after earthwork is excavated so as to reduce the unsupported exposure time of a soil body on the side wall of the foundation pit, control the deformation and stability of foundation pit engineering, and if necessary, a concrete support or a steel support needs to be installed to support the building enclosure. In the prior art, when a steel support is installed, the prefabricated steel support is firstly placed at a preset position, then a loose joint is arranged between the end part of the steel support and a building enclosure, and then prestress is applied, wherein the loose joint is driven by a jack to pressurize once to design pre-applied axial force. The overall structure of the supporting system formed by the mounting mode is poor in combination tightness and stress condition, the problem that the supporting shaft force of the steel support is reduced easily occurs, the preset supporting effect cannot be achieved, and even the falling safety problem occurs.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides the steel support construction method for the underground station open cut interval foundation pit enclosure structure, which has the advantages of simple process, easiness in implementation and high safety and can improve the support stability and reliability.
In order to solve the technical problems, the invention adopts the following technical scheme:
a steel support construction method for a foundation pit support structure of an open cut area of a subway station comprises the following steps:
(S1) respectively installing steel purlins at positions, corresponding to two ends of the steel support to be installed, on the foundation pit support structure;
(S2) hoisting the prefabricated steel support into a foundation pit, and enabling two ends of the steel support to be respectively connected and supported on the steel purlin;
(S3) installing a movable joint for pressurizing between the end part of the steel support and the building enclosure, applying prestress by adopting a mode that a jack drives the movable joint to pressurize successively for two times, wherein the pressure for applying the prestress for the first time is 70% -80% of the designed pre-axial force, the pressure for applying the prestress for the second time is 104% -106% of the designed pre-axial force, then locking and fixing the movable joint, and detaching the jack;
(S4) arranging a falling prevention device for preventing the steel support from falling between the steel support and the building envelope.
In the construction method of the steel support, the total time for installing the steel support and applying the prestress is controlled to be finished within 24 hours.
In the construction method of the steel support, preferably, the deviation of the horizontal axis of the support of the steel support is not more than 30mm, and the deviation of the central elevation of the two ends is not more than 20 mm.
According to the steel support construction method, preferably, after the steel purlin is installed, gaps between the steel purlin and the enclosure structure are backfilled by C20 fine-stone concrete, and prestress can be applied after strength is achieved.
According to the steel support construction method, preferably, when the steel purlin is installed, the plurality of expansion bolts are firstly driven into the pile body of the building envelope, and then the prefabricated steel purlin is connected and fixed with the expansion bolts.
In the above steel support construction method, preferably, the anti-falling device comprises a traction steel pipe, one end of the traction steel pipe is fixedly connected with a hanging ring welded on the steel support, and the other end of the traction steel pipe is fixedly connected with an expansion bolt buried in the enclosure structure and positioned above the steel support.
In the above steel support construction method, preferably, the anti-falling device further comprises a support installed on the envelope structure through an expansion bolt, and the support supports the steel support and/or the steel purlin.
Compared with the prior art, the invention has the advantages that:
according to the construction method of the steel support of the enclosure structure of the foundation pit in the open excavation region of the subway station, after the steel support is initially placed, prestress is applied in a mode of pressurizing successively twice, the pressure for applying the prestress for the first time is smaller than the designed pre-applied axial force and is within 70% -80% of the designed pre-applied axial force, the internal stress of the steel support can be initially released under the pressure, the supporting axial force of the steel support is not easy to change after the prestress is applied for the second time, the stress condition and the combination compactness among the steel support, the swivel head and the enclosure structure can be improved, and the support stability and the reliability are improved. Meanwhile, the pressure for applying the prestress for the second time is set to be 104-106% of the designed prestress, a proper resilience adaptive space is provided, and the supporting effect can be ensured even if the supporting axial force is slightly reduced due to the structural performance of the whole supporting system or the influence of the external environment after the prestress is applied under the condition that the supporting axial force is not overproof. After the prestress is applied, the anti-falling device is arranged to prevent the steel support from falling, so that the safety and the support reliability are ensured. The steel support construction method also has the advantages of simple process and easy implementation.
Drawings
Fig. 1 is a flow chart of a steel support construction method of a foundation pit support structure of an open cut area of a subway station.
Detailed Description
The invention is described in further detail below with reference to the figures and specific examples.
As shown in fig. 1, the steel support construction method for the foundation pit support structure of the open cut area of the subway station of the embodiment includes the following steps:
(S1) respectively installing steel purlins at positions, corresponding to two ends of the steel support to be installed, on the foundation pit support structure;
(S2) hoisting the prefabricated steel support into a foundation pit, and enabling two ends of the steel support to be respectively connected and supported on the steel purlin;
(S3) installing a movable joint for pressurizing between the end part of the steel support and the building enclosure, adopting a jack to drive the movable joint to sequentially pressurize the prestress applying for two times, wherein the pressure for applying the prestress for the first time is 70% -80% of the designed pre-axial force, the pressure for applying the prestress for the second time is 104% -106% of the designed pre-axial force, and then locking and fixing the movable joint; specifically, the loose head is locked and fixed by driving a steel wedge into a reserved hole of the loose head and welding the fixed steel wedge;
(S4) arranging a falling prevention device for preventing the steel support from falling between the steel support and the building envelope.
According to the steel support construction method for the foundation pit support structure of the open excavation region of the subway station, after the steel support is initially placed, prestress is applied in a mode of successively pressurizing for two times, the pressure for applying the prestress for the first time is smaller than the designed pre-applied axial force and is within 70% -80% of the designed pre-applied axial force, the internal stress of the steel support can be initially released under the pressure, the support axial force of the steel support is not prone to change after the prestress is applied for the second time, the stress condition and the combination tightness among the steel support, the swivel head and the support structure can be improved, and the support stability and the reliability are improved. Meanwhile, the pressure for applying the prestress for the second time is set to be 104-106% of the designed prestress, a proper resilience adaptive space is provided, and the supporting effect can be ensured even if the supporting axial force is slightly reduced due to the structural performance of the whole supporting system or the influence of the external environment after the prestress is applied under the condition that the supporting axial force is not overproof. After the prestress is applied, the anti-falling device is arranged to prevent the steel support from falling, so that the safety and the support reliability are ensured. The steel support construction method also has the advantages of simple process and easy implementation.
In the embodiment, the total time for installing the steel support and applying the prestress is controlled to be finished within 24 hours, so that the construction efficiency is ensured, and unsafe factors are avoided as much as possible.
In the embodiment, the deviation of the horizontal axis of the support of the steel support is not more than 30mm, and the deviation of the central elevations of the two ends is not more than 20mm, so that the lasting stability of the support is ensured.
In this embodiment, after the steel purlin is installed, gaps between the steel purlin and the envelope are backfilled with C20 fine aggregate concrete, and prestress can be applied after the strength is achieved.
In this embodiment, when the steel purlin is installed, a plurality of expansion bolts are driven into the pile body of the envelope structure, and then the prefabricated steel purlin is connected and fixed with the expansion bolts. The expansion bolts are adopted to connect the steel enclosing purlin and the pile body of the enclosing structure, and the connecting strength and the stability are good.
In the embodiment, the anti-falling device comprises the traction steel pipe, one end of the traction steel pipe is fixedly connected with the lifting ring welded on the steel support, the other end of the traction steel pipe is fixedly connected with the expansion bolt buried in the enclosure structure and positioned above the steel support, the traction steel pipe pulls the steel support from the upper part, the anti-falling device can effectively prevent falling, and the anti-falling device is simple in structure, low in cost and easy to implement.
In the embodiment, the anti-falling device further comprises a support which is arranged on the envelope structure through an expansion bolt, the support supports the steel support and/or the steel purlin, the support is matched with a traction steel pipe to form an anti-falling system which is pulled up and down, and the reliability is higher.
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-described embodiments. Modifications and variations that may occur to those skilled in the art without departing from the spirit and scope of the invention are to be considered as within the scope of the invention.
Claims (7)
1. A steel support construction method for a foundation pit support structure of an open cut area of a subway station is characterized by comprising the following steps:
(S1) respectively installing steel purlins at positions, corresponding to two ends of the steel support to be installed, on the foundation pit support structure;
(S2) hoisting the prefabricated steel support into a foundation pit, and enabling two ends of the steel support to be respectively connected and supported on the steel purlin;
(S3) installing a movable joint for pressurizing between the end part of the steel support and the building enclosure, applying prestress by adopting a mode that a jack drives the movable joint to pressurize successively for two times, wherein the pressure for applying the prestress for the first time is 70% -80% of the designed pre-axial force, the pressure for applying the prestress for the second time is 104% -106% of the designed pre-axial force, and then locking and fixing the movable joint;
(S4) arranging a falling prevention device for preventing the steel support from falling between the steel support and the building envelope.
2. The steel shotcrete construction method of claim 1, wherein a total time for installing the steel shotcrete and applying the prestress is controlled to be completed within 24 hours.
3. The steel shotcrete construction method of claim 1, wherein the deviation of horizontal axis of the steel shotcrete is not more than 30mm, and the deviation of central elevation of both ends is not more than 20 mm.
4. The steel support construction method according to claim 1, wherein after the steel purlin is installed, gaps between the steel purlin and the building envelope are backfilled with C20 fine-stone concrete, and prestress can be applied after strength is achieved.
5. The steel support construction method according to claim 1, wherein when the steel purlin is installed, a plurality of expansion bolts are driven into a pile body of the building envelope, and then the prefabricated steel purlin is connected and fixed with the expansion bolts.
6. The steel support construction method according to claim 1, wherein the anti-falling device comprises a pulling steel pipe, one end of the pulling steel pipe is fixedly connected with a lifting ring welded on the steel support, and the other end of the pulling steel pipe is fixedly connected with an expansion bolt which is buried in the enclosure structure and is positioned above the steel support.
7. The steel shotcrete construction method of claim 1, wherein the fall arrest device further comprises a support mounted on the enclosure by an expansion bolt, the support supporting the steel shotcrete and/or the steel purlin.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011430076.XA CN112695765A (en) | 2020-12-07 | 2020-12-07 | Steel support construction method for foundation pit enclosure structure of open cut section of subway station |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011430076.XA CN112695765A (en) | 2020-12-07 | 2020-12-07 | Steel support construction method for foundation pit enclosure structure of open cut section of subway station |
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| CN112695765A true CN112695765A (en) | 2021-04-23 |
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| CN202011430076.XA Pending CN112695765A (en) | 2020-12-07 | 2020-12-07 | Steel support construction method for foundation pit enclosure structure of open cut section of subway station |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113356230A (en) * | 2021-06-24 | 2021-09-07 | 中国建筑第二工程局有限公司 | Foundation pit support construction method based on combination of back pressure soil and prestressed steel support |
| CN114960667A (en) * | 2022-05-18 | 2022-08-30 | 河海大学 | Steel pipe support erection construction process |
| CN115110575A (en) * | 2022-06-13 | 2022-09-27 | 中电建南方建设投资有限公司 | Assembling method for assembly type station component |
-
2020
- 2020-12-07 CN CN202011430076.XA patent/CN112695765A/en active Pending
Non-Patent Citations (1)
| Title |
|---|
| 陈韧鸣: ""明挖法地铁车站开挖及支撑体系施工技术应用"", 《中国高新区》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113356230A (en) * | 2021-06-24 | 2021-09-07 | 中国建筑第二工程局有限公司 | Foundation pit support construction method based on combination of back pressure soil and prestressed steel support |
| CN114960667A (en) * | 2022-05-18 | 2022-08-30 | 河海大学 | Steel pipe support erection construction process |
| CN115110575A (en) * | 2022-06-13 | 2022-09-27 | 中电建南方建设投资有限公司 | Assembling method for assembly type station component |
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Application publication date: 20210423 |
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