阅读说明：本技术 一种采用浅埋暗挖法从桩撑支护体系明挖基坑破壁进洞的施工方法 (Construction method for breaking open cut foundation pit wall into hole from pile support supporting system by adopting shallow-buried underground excavation method ) 是由 史宣陶 林刚 徐剑旋 张建祥 柴家远 周明亮 李辉 倪安斌 朱宏海 彭健海 于 2020-05-20 设计创作，主要内容包括：一种采用浅埋暗挖法从桩撑支护体系明挖基坑破壁进洞的施工方法,能大幅提高施工安全性,且能保证后续浅埋暗挖法的施工空间,保证施工效率。包括如下步骤：明挖基坑分层开挖并架设支撑；在明挖基坑侧壁浅埋暗挖隧道第一层初期支护拱部外侧打设大管棚；破除浅埋暗挖隧道拱部上台阶对应的钻孔桩,拱部上台阶开挖完成后,施作该部分对应的第一层初期支护；破除隧道拱部右台阶和隧道拱部左台阶对应处的钻孔桩,开挖该部分土体,接长第一层初期支护；开挖上部预留核心土,接长支撑在下部预留核心土上的临时竖撑；开挖隧道下部右台阶和隧道下部左台阶土体；一次性施作第二层初期支护,拆除临时竖撑,开挖下部预留核心土,完成浅埋暗挖隧道全断面破除基坑侧壁进洞施工。(A construction method for breaking walls of open excavation foundation pits into holes from a pile support supporting system by adopting a shallow-buried underground excavation method can greatly improve construction safety, guarantee construction space of a subsequent shallow-buried underground excavation method and guarantee construction efficiency. The method comprises the following steps: carrying out layered excavation on the open cut foundation pit and erecting a support; arranging a large pipe shed outside a first-layer primary support arch part of a shallow-buried and underground-excavated tunnel on the side wall of the open excavation foundation pit; breaking the drilled piles corresponding to the upper step of the arch part of the shallow-buried underground tunnel, and applying a first layer of primary support corresponding to the upper step of the arch part after the excavation of the upper step of the arch part is finished; breaking the drilled piles at the corresponding positions of the right step of the tunnel arch and the left step of the tunnel arch, excavating the part of soil body, and lengthening a first layer of primary support; excavating reserved core soil on the upper part, lengthening and supporting a temporary vertical support on the reserved core soil on the lower part; excavating a soil body of a right step at the lower part of the tunnel and a left step at the lower part of the tunnel; and (4) constructing a secondary primary support at one time, dismantling the temporary vertical support, excavating the lower part to reserve core soil, and completing the construction of breaking the side wall of the foundation pit into the hole in the full-section shallow-buried excavation tunnel.)

1. A construction method for breaking walls of open cut foundation pits into holes from a pile support supporting system by adopting a shallow-buried underground excavation method comprises the following steps:

firstly, excavating open-cut foundation pits (A) in layers and erecting supports, and then preparing to construct shallow-buried and underground-cut tunnels (B);

secondly, constructing a large pipe shed (21) outside the arch part of a first-layer primary support (22) of the shallow-buried underground tunnel (B);

thirdly, breaking the drilled piles (11) corresponding to the upper step (1) of the arch part of the shallow-buried underground tunnel (B), constructing a first layer of primary support (22) corresponding to the arch part after the excavation of the upper step (1) of the arch part is finished, and arranging temporary vertical supports (24) supported on the upper reserved core soil (3) in the middle of the first layer of primary support (22);

breaking the drilled piles (11) at the corresponding positions of the right step (2a) and the left step (2b) of the tunnel arch, excavating the part of soil body, and lengthening a first layer of primary support (22);

fifthly, excavating the upper reserved core soil (3), lengthening and supporting a temporary vertical support (24) on the lower reserved core soil (5);

excavating a soil body of a right step (4a) and a left step (4b) of the lower part of the tunnel, lengthening a first layer of preliminary support (22), and reserving core soil (5) at the lower part;

and seventhly, constructing a second-layer primary support (23) at one time, removing the temporary vertical support (24), excavating the reserved core soil (5) at the lower part, and completing the construction of breaking the side wall of the foundation pit into the hole at the full section of the shallow-buried underground excavation tunnel (B).

2. The construction method for breaking the wall of the open excavation foundation pit into the hole from the pile support supporting system by adopting the shallow-buried underground excavation method as claimed in claim 1, is characterized in that: the open cut foundation pit (A) adopts a drilled pile (11) and a support system of a counter support (12), and a plate support (13) is arranged at a position of a subsurface excavation interface.

3. The construction method for breaking the wall of the open excavation foundation pit into the hole from the pile support supporting system by adopting the shallow-buried underground excavation method as claimed in claim 1, is characterized in that: and the drilled piles (11) in the hole entering range of the shallow underground excavation tunnel (B) are broken by adopting subsection static force.

4. The construction method for breaking the wall of the open excavation foundation pit into the hole from the pile support supporting system by adopting the shallow-buried underground excavation method as claimed in claim 1, is characterized in that: the first layer of preliminary bracing (22) adopts steel frame sprayed concrete which is fast generated by construction speed and strength.

5. The construction method for breaking the wall of the open excavation foundation pit into the hole from the pile support supporting system by adopting the shallow-buried underground excavation method as claimed in claim 1, is characterized in that: the second-layer primary support (23) is of a cast-in-place reinforced concrete structure, meanwhile, reinforcing steel bars of the second-layer primary support (23) penetrate through the temporary vertical supports (24), and after the temporary vertical supports are poured and reach the designed strength, the temporary vertical supports (24) are cut off at the vault positions of the second-layer primary support (23).

Technical Field

The invention relates to tunnel engineering, in particular to a construction method for breaking walls into holes from open excavation foundation pits of a pile support supporting system by adopting a shallow-buried underground excavation method.

Background

The ground space is tense due to the increase of urban population and human activities, so that the underground space is taken as a resource which is not fully utilized, and the underground space attracts high attention and active development and use of people. The development and the use of the underground space are effective ways for solving the increasing social problems of cities from the environment and the economy, and a large number of urban functions, such as commercial, rail transit, municipal facilities, cultural entertainment and leisure, part of industrial production, storage, disaster prevention and refuge, disaster relief spaces and the like, can be realized in the underground space; meanwhile, the method can achieve various effects of expanding urban space capacity, improving development intensity, promoting smooth traffic, promoting more commercial prosperity, increasing ground greenbelt and beautifying environment, and is a more reasonable development mode compared with a mode of developing to the overhead of a city.

The implementation of urban underground space generally adopts open cut method, cover cut method and underground cut method construction, and the open cut method and the cover cut method construction generally cause a great deal of problems of house removal, pipeline removal and modification, greening removal, traffic dispersion and the like; compared with the underground excavation method, the underground excavation method has the advantages of little influence on ground buildings, roads and underground pipelines, less removal occupied land, less disturbance to residents, less urban environmental pollution and the like, and can be generally divided into a tunnel boring machine construction method and a shallow buried underground excavation method, wherein the tunnel boring machine construction method is generally suitable for excavating tunnels with regular sections and moderate lengths; the shallow-buried underground excavation method has the advantages of variable structural types, low manufacturing cost and no need of too many special equipment, and is widely applied to the development of underground spaces of cities in China. The shallow buried underground excavation underground cavern generally has the characteristics of shallow buried depth, poor stratum lithology, underground water development, complex surrounding environment and the like; an open-cut foundation pit (including a vertical shaft) is usually arranged at an open place on the ground to serve as a subsurface excavation construction working surface, a supporting system of piles and inner supports is usually adopted for the open-cut foundation pit, and in order to ensure the construction safety of wall breaking and shallow-buried excavation in the foundation pit, generally, a main body structure in the foundation pit is poured to form a closed stress system, and then a guard pile is broken at the side wall of the foundation pit to carry out shallow-buried excavation construction; however, the method has great adverse effects on the slag discharge, feeding and construction operation space of the later shallow-buried and underground-excavated tunnel.

For the above reasons, it is necessary to review and research a construction method for breaking the wall of the open excavation foundation pit into the hole from the pile support supporting system by using the shallow-buried underground excavation method.

Disclosure of Invention

The invention aims to solve the technical problem of providing a construction method for breaking walls and entering holes of an open cut foundation pit from a pile support supporting system by adopting a shallow-buried underground excavation method, which can greatly improve the safety of breaking the enclosing pile and entering the holes from the side wall of the open cut foundation pit by adopting the shallow-buried underground excavation method, ensure the construction space of the subsequent shallow-buried underground excavation method and ensure the construction efficiency.

The technical scheme adopted by the invention for solving the technical problems is as follows:

the invention relates to a construction method for breaking open cut foundation pit walls into a hole from a pile support supporting system by adopting a shallow-buried underground excavation method, which comprises the following steps:

firstly, after open-cut foundation pits are excavated in layers and supports are erected, shallow-buried and underground-excavated tunnels are prepared for construction;

secondly, arranging a large pipe shed outside a first-layer primary support arch part of the shallow-buried and underground-excavated tunnel on the side wall of the open-excavated foundation pit;

breaking the drilled piles corresponding to the upper step of the arch part of the shallow-buried underground tunnel, constructing a first layer of primary support corresponding to the arch part after the excavation of the upper step of the arch part is finished, and arranging a temporary vertical support supported on the upper reserved core soil in the middle of the primary support of the first layer;

breaking the drilled piles at the corresponding positions of the right step of the tunnel arch and the left step of the tunnel arch, excavating the part of soil body, and lengthening a first layer of primary support;

fifthly, excavating the upper reserved core soil, lengthening and supporting a temporary vertical support on the lower reserved core soil;

excavating a right step of the lower part of the tunnel and a soil body of the left step of the lower part of the tunnel, lengthening a first layer of primary support, and reserving core soil at the lower part;

and seventhly, constructing a second-layer primary support at one time, dismantling the temporary vertical supports, excavating the lower part reserved with core soil, and completing the construction of breaking the side wall of the foundation pit into the hole on the full section of the shallow-buried underground tunnel.

The method has the advantages that the open-cut foundation pit fender post is broken by sections, the temporary vertical supports are arranged at the arch parts of the tunnels, and after the soil bodies on the two sides of the lower part of the tunnel are excavated and the second layer of primary support is added, the temporary vertical supports are removed, so that the safety of breaking the fender post from the side wall of the open-cut foundation pit and entering the tunnel by adopting a shallow-buried underground excavation method can be greatly improved; and basically, the slag discharge, feeding and mechanical operation space of the later-stage shallow-buried underground excavation method are not influenced, and the construction efficiency is ensured.

Drawings

The specification includes the following two figures:

FIG. 1 is a schematic plan layout view of a construction method for breaking walls and entering holes of open-cut foundation pits of a pile support supporting system by adopting a shallow-buried underground excavation method;

fig. 2 is a schematic sectional view of a tunnel portal in a construction method for breaking walls of open cut foundation pits into the tunnel from a pile support supporting system by adopting a shallow-buried underground excavation method.

The figures show the parts, components and corresponding marks: the method comprises the following steps of open excavation foundation pit A, shallow excavation tunnel B, drilled pile 11, butt support 12, plate support 13, large pipe shed 21, primary support 22 of the first layer, primary support 23 of the second layer, temporary vertical support 24, tunnel arch upper step 1, tunnel arch right step 2a, tunnel arch left step 2B, upper reserved core soil 3, tunnel lower right step 4a, tunnel lower left step 4B and lower reserved core soil 5.

Detailed Description

The invention is further illustrated by the following figures and examples.

Referring to fig. 1 and 2, the construction method for breaking open cut foundation pit wall into hole from a pile support system by adopting a shallow-buried underground excavation method comprises the following steps:

firstly, excavating an open-cut foundation pit A in a layered mode and erecting supports, and preparing to construct a shallow-buried and underground-cut tunnel B;

secondly, a large pipe shed 21 is arranged on the outer side of the arch part of a first-layer primary support 22 of the shallow-buried underground tunnel B;

thirdly, breaking the bored pile 11 corresponding to the upper step 1 of the arch part of the shallow underground tunnel B, constructing a first layer of primary support 22 corresponding to the upper step 1 after the excavation of the arch part is finished, and arranging a temporary vertical support 24 supported on the upper reserved core soil 3 in the middle of the first layer of primary support 22;

fourthly, breaking the drilled piles 11 at the corresponding positions of the right step 2a and the left step 2b of the tunnel arch, excavating the part of soil body, and lengthening the first layer of preliminary bracing 22;

fifthly, excavating the upper reserved core soil 3, lengthening and supporting a temporary vertical support 24 on the lower reserved core soil 5;

excavating a soil body of a right step 4a and a left step 4b of the lower part of the tunnel, lengthening a first layer of primary support 22, and reserving core soil 5 at the lower part;

and seventhly, constructing a second-layer primary support 23 at one time, removing the temporary vertical support 24, excavating the reserved core soil 5 at the lower part, and completing the construction of breaking the side wall of the foundation pit into the hole at the full section of the shallow-buried underground tunnel B.

According to the invention, through breaking open cut foundation pit fender posts in sections, arranging the temporary vertical braces at the arch part of the tunnel, and dismantling the temporary vertical braces after the soil bodies on two sides of the lower part of the tunnel are excavated and a second layer of primary support is added, the safety of shallow-buried and hidden-excavated holes entering through breaking the fender posts on the side wall of the open cut foundation pit can be greatly improved; meanwhile, the slag discharging, feeding and mechanical operation space of later-stage shallow-buried subsurface excavation is basically unaffected, sufficient construction space is provided for a subsequent shallow-buried subsurface excavation method, and the construction efficiency is guaranteed.

Referring to fig. 1, the open cut foundation pit a adopts a drilled pile 11 and a counter support 12 supporting system, and a slab support 13 is arranged at a subsurface excavation interface. The first-layer primary support 22 adopts steel frame sprayed concrete which is generated quickly by construction speed and strength so as to achieve the purpose of supporting the broken bored pile 11 as soon as possible. The second-layer primary support 23 is of a cast-in-place reinforced concrete structure, meanwhile, reinforcing steel bars of the second-layer primary support 23 penetrate through the temporary vertical supports 24, and after the second-layer primary support 23 is poured and reaches the designed strength, the temporary vertical supports 24 are cut off at the vault positions of the second-layer primary support 23.

Referring to fig. 2, the bored pile 11 in the hole entering range of the shallow underground tunnel B should be broken by using a segmental static force to ensure the safety of a foundation pit supporting system.

The foregoing merely illustrates the principles and practice of the invention and is not intended to limit the invention to the exact forms and parameters illustrated and described, and accordingly, all modifications and equivalents that may be resorted to are intended to fall within the scope of the invention.