阅读说明：本技术 既有洞室侧向新建为大断面隧道的爬升反向施工法 (Climbing reverse construction method for newly building large-section tunnel in existing cavern side direction ) 是由 陈二平 刘永明 冀荣华 杨永强 王刚 李艳厂 刘宁 黄义雄 于 2019-10-29 设计创作，主要内容包括：本发明公开了一种既有洞室侧向新建为大断面隧道的爬升反向施工法,在既有洞室内采用先爬升进洞开挖上台阶,然后折回开挖其余上台阶,再次折回开挖中台阶和下台阶,最后反向完成交叉口挑顶,从而完成既有洞室侧向新建为大断面隧道的施工。对于地表沉降要求较高,但围岩级别较差(Ⅳ级)的地下洞室的工程时,本发明的施工方法先爬升进洞开挖上台阶,然后折回开挖其余上台阶,再次折回开挖中台阶和下台阶,最后反向完成交叉口挑顶。其优点是能够在施工爬升段后使用台阶法开挖,台阶法和爬升段创新性地结合,控制了地表的沉降和围岩的位移变形,确保了施工的安全,保证了围岩的稳定,有效地控制了地表沉降。(The invention discloses a climbing reverse construction method for newly building a large-section tunnel in the existing cavern in the lateral direction. When the construction method is used for the engineering of the underground cavern with higher requirement on surface subsidence but poor surrounding rock level (IV level), the construction method firstly climbs into the tunnel to excavate the upper step, then turns back to excavate the rest of the upper step, turns back to excavate the middle step and the lower step again, and finally reversely finishes intersection top-lifting. The construction method has the advantages that the step method can be used for excavating after the construction climbing section, the step method is innovatively combined with the climbing section, the settlement of the earth surface and the displacement deformation of the surrounding rock are controlled, the construction safety is ensured, the stability of the surrounding rock is ensured, and the settlement of the earth surface is effectively controlled.)

1. A climbing reverse construction method for newly building a large-section tunnel in the lateral direction of an existing cavern is characterized in that: climbing into a tunnel to excavate an upper step in the existing cavern, then turning back to excavate other upper steps, turning back to excavate a middle step and a lower step again, and finally reversely completing intersection top-lifting, thereby completing construction of newly building a large-section tunnel in the existing cavern side direction.

2. The climbing reverse construction method for newly building the existing cavern into the large-section tunnel in the lateral direction according to claim 1, which is characterized in that: the specific construction method comprises the following steps:

A. excavating in a climbing section: firstly, excavating a lower section at the opening during construction, manufacturing a profile steel gantry at the opening to serve as a temporary support, excavating an upper section in an obliquely upward mode through full-section excavation of a temporary climbing channel, climbing to the arch crown elevation during excavation, setting the elevation of the bottom of the temporary climbing channel to be the arch camber line height of the section of the cavern, immediately spraying concrete after excavation, applying an anchor rod and I-steel after the spraying of a first layer is finished, and spraying concrete for the second time after the spraying of the first layer is finished;

B. performing forward excavation on the upper step, namely excavating the surrounding rock of the upper step in the residual length range of the extension cavity in a left and a right manner by adopting a middle partition wall method after the temporary climbing channel climbs to a preset height, firstly performing advanced grouting on a left half arch part small conduit, excavating an ① # area in the left half, performing primary support and temporary middle partition wall support, then performing advanced grouting on the right half arch part small conduit, excavating a ② # area in the right half, and timely performing primary support;

C. and (3) carrying out reverse excavation of the upper step: after the forward excavation of the upper step is finished, excavating towards the existing cavern along the temporary climbing channel in a reverse direction by adopting a full-section method, filling and leveling the temporary climbing channel by using crushed slag when performing reverse expanding excavation, and arranging a steel pipe channel for personnel communication and concrete pumping in the original temporary climbing channel;

D. and (3) carrying out middle and lower step construction: after excavation and supporting of an upper step of an extension cavern are completed, firstly, removing waste slag in a temporary climbing channel, dismantling a steel pipe temporary channel, dividing the rest part of a lower rock mass into two steps of excavation of a middle step and a lower step, dividing the excavation and supporting operation into 4 areas during construction, carrying out sequential excavation and supporting operation according to serial numbers in a drawing, timely carrying out primary supporting after excavation is completed, and carrying out secondary lining after primary supporting and surrounding rock displacement tend to be stable;

E. carrying out top picking construction: after the tunnel face is pushed to the side wall of the existing cavern, the filling slag in the early temporary climbing channel is transferred to the interior of the main cavern, the ground of the main cavern is filled to a designed elevation, the construction rack is erected on filling soil, the top surrounding rocks of the intersection part of the newly-built cavern and the existing cavern are gradually excavated by adopting a circulating footage and are timely constructed to be a primary support, a secondary lining is constructed after the primary support and the surrounding rocks are stable in displacement, and the footage is less than or equal to 1m each time.

3. The climbing reverse construction method for newly building the existing cavern into the large-section tunnel in the lateral direction according to claim 2, which is characterized in that: in the step A, the temporary climbing channel is obliquely arranged upwards by 25 degrees, when an upper section is excavated, the single advancing length is 2m, the section height of a starting point is 5m, the section height of a terminal point is 6m, the following advancing length of the climbing section excavation is controlled within 2m, concrete spraying is immediately carried out after the excavation, and the spraying thickness of a first layer is 5 cm.

4. The climbing reverse construction method for newly building the existing cavern into the large-section tunnel in the lateral direction according to claim 2, which is characterized in that: and in the step B, the step pitch of the left half-width excavation and the right half-width excavation is controlled to be 9-11m, excavation is carried out by adopting a controlled blasting mode, and the footage of each circulation is less than or equal to 1.5 m.

5. The climbing reverse construction method for newly building the existing cavern into the large-section tunnel in the lateral direction according to claim 2, which is characterized in that: in step C, the diameter of the steel pipe passage is 2 m.

6. The climbing reverse construction method for newly building the existing cavern into the large-section tunnel in the lateral direction according to claim 2, which is characterized in that: and D, when excavation and supporting operation is carried out according to the serial numbers in the drawing, the circulating footage length is less than or equal to 2m, the step distance of the half-width middle-lower step is controlled to be 6-10m, and the step distances of the left step and the right step are controlled to be 10-20 m.

Technical Field

The invention relates to a construction method of a tunnel, in particular to a climbing reverse construction method for newly building a large-section tunnel in the lateral direction of an existing cavern.

Background

The underground cavern engineering in China has more projects, so the excavation and supporting technology of the underground cavern engineering is mature, but the construction technology for expanding and excavating a larger cavern with a certain intersection angle with the existing cavern is less under the condition of ensuring the stability of the existing tunnel cavern. The existing cavern has a larger section difference with the newly built expanded cavern, namely a small section is changed into a large section, and the expanded cavern is not the in-situ expanded cavern of the existing cavern and has a certain intersection angle with the existing cavern. When the cavern is integrally divided into three-step excavation and the upper step cannot be excavated directly at the entrance to the cave, how to safely enter the cave becomes a difficult point. The construction process inevitably disturbs the surrounding rock of the original cavern, so that the stability of the surrounding rock needs to be ensured and the original cavern and the newly excavated cavern form a whole. Therefore, how to ensure the stability of the existing tunnel and the smooth progress of the extension project when the tunnel is re-excavated and extended becomes a technical problem to be solved urgently.

Disclosure of Invention

The invention aims to provide a climbing reverse construction method for newly building a large-section tunnel in the lateral direction of an existing cavern. The method can ensure the stability of the existing tunnel and the smooth operation of the extension project when the tunnel is changed, excavated and extended.

The technical scheme of the invention is as follows: a climbing reverse construction method for newly building a large-section tunnel in the existing cavern in the lateral direction is characterized in that the climbing is firstly adopted in the existing cavern to dig an upper step, then the climbing is turned back to dig the rest upper steps, the middle step and the lower step are turned back to dig again, and finally intersection top-lifting is reversely completed, so that construction of newly building the large-section tunnel in the existing cavern in the lateral direction is completed.

In the climbing reverse construction method for newly building a large-section tunnel in the existing cavern side direction, the specific construction method comprises the following steps:

A. excavating in a climbing section: firstly, excavating a lower section at the opening during construction, manufacturing a profile steel gantry at the opening to serve as a temporary support, excavating an upper section in an obliquely upward mode through full-section excavation of a temporary climbing channel, climbing to the arch crown elevation during excavation, setting the elevation of the bottom of the temporary climbing channel to be the arch camber line height of the section of the cavern, immediately spraying concrete after excavation, applying an anchor rod and I-steel after the spraying of a first layer is finished, and spraying concrete for the second time after the spraying of the first layer is finished;

B. performing forward excavation on the upper step, namely excavating the surrounding rock of the upper step in the residual length range of the extension cavity in a left and a right manner by adopting a middle partition wall method after the temporary climbing channel climbs to a preset height, firstly performing advanced grouting on a left half arch part small conduit, excavating an ① # area in the left half, performing primary support and temporary middle partition wall support, then performing advanced grouting on the right half arch part small conduit, excavating a ② # area in the right half, and timely performing primary support;

C. and (3) carrying out reverse excavation of the upper step: after the forward excavation of the upper step is finished, excavating towards the existing cavern along the temporary climbing channel in a reverse direction by adopting a full-section method, filling and leveling the temporary climbing channel by using crushed slag when performing reverse expanding excavation, and arranging a steel pipe channel for personnel communication and concrete pumping in the original temporary climbing channel;

D. and (3) carrying out middle and lower step construction: after excavation and supporting of an upper step of an extension cavern are completed, firstly, removing waste slag in a temporary climbing channel, dismantling a steel pipe temporary channel, dividing the rest part of a lower rock mass into two steps of excavation of a middle step and a lower step, dividing the excavation and supporting operation into 4 areas during construction, carrying out sequential excavation and supporting operation according to serial numbers in a drawing, timely carrying out primary supporting after excavation is completed, and carrying out secondary lining after primary supporting and surrounding rock displacement tend to be stable;

E. carrying out top picking construction: after the tunnel face is pushed to the side wall of the existing cavern, the filling slag in the early temporary climbing channel is transferred to the interior of the main cavern, the ground of the main cavern is filled to a designed elevation, the construction rack is erected on filling soil, the top surrounding rocks of the intersection part of the newly-built cavern and the existing cavern are gradually excavated by adopting a circulating footage and are timely constructed to be a primary support, a secondary lining is constructed after the primary support and the surrounding rocks are stable in displacement, and the footage is less than or equal to 1m each time.

In the climbing reverse construction method for newly building a large-section tunnel in the existing cavern side direction, in the step a, the temporary climbing channel is set to be inclined upward by 25 degrees, when an upper section is excavated, a single advancing length is 2m, the starting point section height is set to be 5m, the end point section height is set to be 6m, the excavating advancing length of the climbing section is controlled within 2m, concrete spraying is immediately performed after excavating, and the spraying thickness of the first layer is 5 cm.

In the climbing reverse construction method for newly building the existing cavern into the large-section tunnel in the lateral direction, in the step B, the left and right half-width excavation steps are controlled to be 9-11m, excavation is carried out by adopting a controlled blasting mode, and the footage is less than or equal to 1.5m in each circulation.

In the climbing reverse construction method for newly building a large-section tunnel in the existing cavern side direction, in the step C, the diameter of the steel pipe channel is 2 m.

In the climbing reverse construction method for newly building a large-section tunnel in the existing chamber side direction, in the step D, when excavation and supporting operation is performed according to the serial number in the drawing, the circulating footage length is less than or equal to 2m, the half-width middle-lower step distance is controlled to be 6-10m, and the left step distance and the right step distance are controlled to be 10-20 m.

The invention has the beneficial effects that: compared with the prior art, when the construction method is used for the engineering of the underground cavern with higher requirement on surface subsidence but poorer surrounding rock level (IV level), the construction method firstly climbs into the tunnel to excavate the upper step, then turns back to excavate the rest upper steps, turns back to excavate the middle step and the lower step again, and finally reversely finishes intersection top-lifting. The construction method has the advantages that the step method can be used for excavating after the construction climbing section, the step method is innovatively combined with the climbing section, the settlement of the earth surface and the displacement deformation of the surrounding rock are controlled, the construction safety is ensured, the stability of the surrounding rock is ensured, and the settlement of the earth surface is effectively controlled. The stability of the existing tunnel and the smooth proceeding of the extension project are ensured when the tunnel is changed, excavated and extended.

In the whole construction process, when the cavern is expanded by adopting a step method, the cavern needs to be excavated from the upper step, but because the section of the existing cavern is smaller, the stability of the existing cavern is greatly influenced if the upper step is directly excavated from the existing cavern, and the construction method of the invention firstly constructs a climbing section and then excavates the upper step, thereby avoiding the stability influence on the existing cavern in the process of excavating the upper step.

The upper step is reversely expanded and excavated after the forward construction of the upper step, the top of the cantilever can be constructed after the reverse expansion and excavation, and the stability of surrounding rocks above the arch part of the existing cavern is ensured.

The problem of underground cavern engineering can't guarantee the stability when the small cross section expands to digging to big cross section when subsiding the relatively high and relatively poor country rock of requirement is solved.

Drawings

FIG. 1 is a general construction flow diagram;

FIG. 2 is an excavation section of an extension cavity;

FIG. 3 is a cross-sectional view of an enlarged cavity;

FIG. 4 is a cross-sectional view of the climbing section;

FIG. 5 is an enlarged cavern cross-sectional view;

FIG. 6 is a schematic view of the reverse upper step excavation;

FIG. 7 is a sequence diagram of the construction of the middle and lower steps;

FIG. 8 is a schematic diagram of forward excavation of the middle and lower steps;

figure 9 is a side view of the flip top construction.

Reference numerals: 1-existing cavern section; 2-climbing section; 3-a steel pipe passage with the diameter of 2 m; 4-upper step reverse expanding excavation section; 5, positively excavating a section of the middle and lower steps; 6-top picking section; 7-a waste slag landfill area; 8-excavating an upper step; 9-excavating middle steps; and 10, excavating a lower step.

Detailed Description

The invention is further illustrated by the following figures and examples, which are not to be construed as limiting the invention.

The embodiment of the invention comprises the following steps: a climbing reverse construction method for newly building a large-section tunnel in the lateral direction of an existing cavern is disclosed, as shown in the attached figures 1-9, and the basic idea is as follows: climbing into a tunnel to excavate an upper step in the existing cavern, then turning back to excavate other upper steps, turning back to excavate a middle step and a lower step again, and finally reversely completing intersection top-lifting, thereby completing construction of newly building a large-section tunnel in the existing cavern side direction.

The specific construction method comprises the following steps:

the first step is as follows: making climbing segment excavation

According to the field construction conditions, an opening is arranged in the middle of the existing cavern section 1, a lower section is excavated at the opening in construction, the width and the height of the opening are determined according to the field conditions, a section steel portal frame is manufactured at the opening to serve as a temporary support, an upper section is excavated in a mode of full-section excavation of a temporary climbing channel with the angle of 25 degrees upwards, and the depth is 2 m. As shown in fig. 4, a is a starting point section, b is an end point section, the starting point section height is set to be 5m, and the end point section height is set to be 6m in fig. 4, so as to rapidly reach the vault of the enlargement cavern. And excavating and climbing to the elevation of the vault, wherein the elevation of the bottom of the temporary climbing channel is the height of the arch forming line of the cross section of the cavern. And controlling the excavation follow-up running length of the climbing section 2 within 2m, immediately spraying concrete after excavation, wherein the spraying thickness of a first layer is 5cm, then applying an anchor rod and I-shaped steel, and performing second concrete spraying after the construction is finished, as shown in figures 3 and 4.

The third step: performing forward excavation on the upper bench

After the temporary climbing channel climbs to a preset height, the upper step surrounding rock in the residual length range of the enlargement chamber is respectively excavated in a left frame and a right frame by adopting a mid-partition wall method, a left half arch advanced grouting small guide pipe is firstly constructed, a left half frame, namely an ① number area, is constructed, an initial support and a temporary mid-partition wall support are simultaneously constructed, a right half arch advanced grouting small guide pipe is constructed, a right half frame excavation, namely a ② number area, is constructed, the initial support is timely constructed, the step distance between the left half frame and the right half frame is controlled to be about 10m, the excavation is carried out by adopting a controlled blasting mode, and the footage per cycle is not more than 1.5m, as shown in figure 5.

The fourth step: performing reverse excavation of upper bench

After the forward excavation of the upper step is finished, the full-section method excavation is adopted along the temporary climbing channel in the reverse direction to the existing grotto direction, and the upper step reverse expanding excavation section 4 is excavated. When reverse expanding excavation is carried out, the temporary climbing channel needs to be filled and leveled by using crushed slag to ensure that a construction rack has a firmer foundation, but personnel and material transportation is restricted, so that 1 steel pipe channel 3 with the diameter of 2m is arranged in the original channel for personnel to pass and concrete to pump. The inside of the 2m diameter steel pipe channel 3 is provided with steps for personnel to pass through, and simultaneously, pumped concrete and mechanical fuel are input, as shown in figure 6.

The fifth step: construction of middle and lower steps

And after the excavation and the support of the upper step of the extension cavern are finished, namely the excavation of the upper step 8 is finished, excavating the forward excavation section 5 of the middle step and the lower step, namely excavating the middle step 9 and excavating the lower step 10. During excavation, the temporary climbing channel is cleaned to remove slag, the steel pipe channel 3 with the diameter of 2m is dismantled, and the rest part of the rock mass at the lower part is excavated in two steps, namely a middle step and a lower step. The construction is divided into 4 areas, the four areas are divided into four areas I, II, III and IV according to the serial numbers in figure 7, the four areas are sequentially excavated and supported, the length of each circulation footage is not more than 2m, the step distance of the half-width middle-lower step is controlled to be 6-10m, and the step distances of the left step and the right step are controlled to be 10-20 m. And (5) performing primary support in time after excavation is finished. And (3) constructing a secondary lining after the primary support and the surrounding rock displacement tend to be stable, as shown in figures 6 and 7.

And a sixth step: construction of the overhanging section 6

After the tunnel face is pushed to the side wall of the existing cavern, the filling slag in the early temporary climbing channel is transferred to the interior of the main cavern and accumulated at a waste slag filling area 7 shown in fig. 9, so that the ground of the main cavern is filled to a designed elevation, the construction rack is erected on filling soil, surrounding rocks at the top of the intersection part of the newly-built cavern and the existing cavern are gradually excavated by adopting a circulating footage and are timely constructed to be a primary support, a secondary lining is constructed after the primary support and the surrounding rock displacement tend to be stable, and the circulating footage is less than or equal to 1m each time. As shown in fig. 8.