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Construction deformation control method for lower step of high crustal stress weak surrounding rock tunnel

A technology of weak surrounding rock and high in-situ stress, applied in tunnels, tunnel linings, underground chambers, etc., can solve problems such as damage, and achieve the effects of accelerating cycle time, fast overall construction progress, and reduced slag output.

Active Publication Date: 2015-06-03
CHINA RAILWAY NO 2 ENG GRP CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is: in view of the above situation, provide a method for controlling the deformation of the lower steps of tunnels with high ground stress and weak surrounding rocks. The large deformation in the front leads to the failure and destruction of the system support formed on the upper step

Method used

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  • Construction deformation control method for lower step of high crustal stress weak surrounding rock tunnel
  • Construction deformation control method for lower step of high crustal stress weak surrounding rock tunnel
  • Construction deformation control method for lower step of high crustal stress weak surrounding rock tunnel

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Experimental program
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Effect test

Embodiment 1

[0093] 1) Construction preparation:

[0094] Monitor the state of the support and surrounding rock of the upper step, and determine the stable state of the surrounding rock by the convergence index. The so-called stability of the surrounding rock means that the deformation rate around the tunnel is less than the convergence index. After the surrounding rock is stable, the lower step construction will be carried out. The measures of adding anchor rods and spraying concrete are adopted to strengthen the support system of the upper step. When the convergence rate of the surrounding rock of the upper step is less than 0.2mm / day, the surrounding rock tends to be stable;

[0095] 2) Excavation of surrounding rock for lower steps:

[0096] The excavation height of the lower steps is 0.45 times the designed excavation height of the tunnel, the footage per cycle is 1.5m, and the amount of blasting agent used for a single blast reaches 200kg. It takes 45 hours to complete excavation, sl...

Embodiment 2

[0128] 1) Construction preparation:

[0129] Monitor the state of the support and surrounding rock of the upper step, and determine the stable state of the surrounding rock by the convergence index. The so-called stability of the surrounding rock means that the deformation rate around the tunnel is less than the convergence index. After the surrounding rock is stable, the lower step construction will be carried out. The measures of adding anchor rods and spraying concrete are adopted to strengthen the support system of the upper step. When the convergence rate of the surrounding rock of the upper step is less than 0.2mm / day, the surrounding rock tends to be stable;

[0130] 2) Excavation of surrounding rock for lower steps:

[0131] The excavation height of the lower bench is 0.5 times the designed excavation height of the tunnel, the footage per cycle is 2.5m, and the amount of blasting agent used for a single blast reaches 300kg. It takes 45 hours to complete excavation, sla...

Embodiment 3

[0163] 1) Construction preparation:

[0164] Monitor the state of the support and surrounding rock of the upper step, and determine the stable state of the surrounding rock by the convergence index. The so-called stability of the surrounding rock means that the deformation rate around the tunnel is less than the convergence index. After the surrounding rock is stable, the lower step construction will be carried out. The measures of adding anchor rods and spraying concrete are adopted to strengthen the support system of the upper step. When the convergence rate of the surrounding rock of the upper step is less than 0.2mm / day, the surrounding rock tends to be stable;

[0165] 2) Excavation of surrounding rock for lower steps:

[0166] The excavation height of the lower bench is 0.46 times the designed excavation height of the tunnel, the footage per cycle is 2m, and the amount of blasting agent used for a single blast reaches 250kg. It takes 48 hours to complete excavation, slag...

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Abstract

The invention discloses a construction deformation control method for lower step of high crustal stress weak surrounding rock tunnel. The weak surrounding rock tunnel is constructed in a step method. When an upper step is excavated and formed, and surrounding rock tends to be stable, the lower step is constructed. The lower step is finished in two steps. Firstly, a middle of the lower step is reversely excavated, and arch walls on two side of the middle groove are immediately reinforced by long anchor rods after excavation is finished. Secondly, a working face and arch walls at the height range of the lower step are secondarily reinforced through long anchor rods, and secondary drop bottom excavation is performed after reinforcement is finished. The construction deformation control method has the advantages that deformation surrounding rock in construction processes of the lower step is controlled, blasting excavation is divided into two steps by using the method of firstly excavating the middle groove, chemical using amount of each time is reduced by a half than drop bottom excavation of the lower step, disturbance of blasting on the surrounding rock is greatly reduced, working amount of the excavation of the working face is reduced, circulation time for forming support is shortened, secondary expansion excavation is avoided, whole construction speed is quickened, and safety is guaranteed.

Description

technical field [0001] The invention relates to a deformation control method for the construction of lower steps of tunnels with high ground stress and weak surrounding rocks. Background technique [0002] After the excavation of tunnels with weak surrounding rocks, the deformation of the surrounding rocks is relatively large. The reserved deformation is not only related to the characteristics of the surrounding rocks, buried depth, ground stress, and tunnel diameter, but also to the support conditions, stiffness, and support time. Therefore, after the key factors of the tunnel surrounding rock lithology, buried depth, tunnel diameter and ground stress are determined, the support type, time, and stiffness of the support structure become the key to determine the deformation of the surrounding rock. Before the excavation of the lower step, the support system of the upper step has been formed, and the surrounding rock has tended to be stable. The excavation of the lower step wi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21D11/10E21D21/00
Inventor 辜文凯卿三惠杨家松沙宗天刘士恩杨龙伟
Owner CHINA RAILWAY NO 2 ENG GRP CO LTD
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