A construction method for deep buried soft rock tunnel

Abstract

The invention discloses a construction method of a deeply-buried soft rock tunnel. The construction method of the deeply-buried soft rock tunnel comprises the following steps that 1, basic mechanicalparameters of surrounding rock are determined; 2, a primary support structure of the tunnel is determined; a tunnel side wall instability judgment is carried out; a top plate caving arch rise of the tunnel side wall in a stable state is determined; the top plate caving arch rise of the tunnel side wall in a cracking-sliding-type shear failure state of the tunnel side wall and a sliding face dip angle, an inner side height, an outer side height and collapse width of the side wall cracking and sliding collapse area are determined; the top plate caving arch rise of the tunnel side wall in an inclined surface shear failure state of the tunnel side wall and collapse width in a side wall inclined surface collapse area are determined; support structure is determined; 3, tunnel excavation and primary support structure construction are carried out; 4, a second lining construction of tunnel is carried out; 5, construction of the next section is carried out, and 6, step 5 is repeated multiple times until all tunnel constructions are completed. The construction method of the deeply-buried soft rock tunnel can carry out a design for the support structure of the tunnel anchoring support system based on the tunnel side wall instability judgment, and the deformation and failure of tunnel surrounding rock can be effectively controlled and the construction cost is low.

Description

technical field [0001] The invention belongs to the technical field of tunnel construction, and in particular relates to a construction method for a deep buried soft rock tunnel. Background technique [0002] In recent years, with the rapid development of my country's transportation industry, a large number of deep-buried mountain tunnels will pass through water-rich and high-in-situ stress areas. Improper construction will easily lead to the reduction of the tunnel section and the instability of the supporting structure, which will seriously affect the rapid construction of the tunnel and the safe operation in the future. For a long time, many experts and scholars have carried out in-depth research on the deformation mechanism and support technology of soft rock tunnels (also known as weak surrounding rock tunnels). He Benguo et al. took the Muzhailing high geostress tunnel as the engineering background, analyzed the deformation characteristics, energy accumulation, mechani...

AI Technical Summary

Problems solved by technology

[0004] Although many research results have been obtained in the deformation of surrounding rock and support technology of soft rock tunnels, and the research on the collapse and floor heaving of soft rock tunnels is also relatively in-depth, but the research on the common tunnel spall disasters in soft rock tunnels is still incomplete. Rarely, on-site treatment measures for slabs still rely on construction experience, and the treatment effect is not ideal

Especially for soft rock tunnels with unstable side walls, there is almost no construction experience for reference

[0005] In addition, practice has shown that the basic theory of Platts' caving arch reflects the objective law of ground pressure to a certain extent, but there are still the following deficiencies in soft rock engineering: First, there is a lack of stability conditions for tunnel side walls (also called tunnel sides) Research: Studies have shown that the stability of the tunnel side wall is closely related to the strength of the rock mass itself, the depth of the tunnel, and the excavation height of the tunnel. When the lithology of the tunnel side wall and the tunnel depth are constant, the greater the tunnel height The worse its stability is; Research: When the tunnel side wall is unstable, the side wall will undergo shear failure, such as pull cracking-slip shear failure and single-slope shear failure

Therefore, when applying the basic theory of Platts' caving arch to calculate the caving arch sagittal height and determine the surrounding rock pressure, there are often deviations, which directly affect the accuracy of tunnel support parameters determination.

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