Stage division method for large deformations of tunnel surrounding rock in survey and design stage

Abstract

The invention relates to the technical field of rock mass engineering, and provides a stage division method for large deformations of tunnel surrounding rock in a survey and design stage. Firstlylargedeformation grades of the surrounding rock are divided into n grades; then the maximum principal stress, lithology and rock mass integrity data, and active fault data of a tunnel site area are obtained; then the maximum principal stress and the lithology and rock mass integrity data of the tunnel site area are combined for performing an initial assessment, and the maximum principal stress and theactive fault data of the tunnel site area are combined for performing a second preliminary assessment to calculate the preliminary assessment grade of the surrounding rock large deformation in the tunnel site area; then groundwater situation data, the angle between the rock layer direction and the tunnel axis, and the inclination of the rock layer in the tunnel site area are obtained and combinedto calculate grade correction parameters to correct the preliminary assessment grade of the surrounding rock large deformations in the tunnel site area to obtain the surrounding rock large deformation correction level in the tunnel site area. According to the stage division method for the large deformations of the tunnel surrounding rock in the survey and design stage, the risk level of the large-scale deformation disaster of the surrounding rock in the survey and design stage can be evaluated, index selection is relatively comprehensive and easy to obtain, and thus the grade division accuracy is improved.

Description

technical field [0001] The invention relates to the technical field of rock mass engineering, in particular to a method for grading the large deformation of tunnel surrounding rock in the survey and design stage. Background technique [0002] The large deformation of the surrounding rock is a phenomenon in which the rock mass around the excavation surface of the underground engineering forms a significant deformation under the action of engineering disturbance stress and expansion stress, which exceeds the allowable value of the engineering design. The large deformation of the surrounding rock under high stress extrusion usually has the characteristics of large deformation, high deformation rate, long duration, various support failure forms, and large damage range of the surrounding rock, which will cause great damage to the normal construction and operation of the tunnel. threats to personal safety and economic losses. [0003] At present, my country's infrastructure const...

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Problems solved by technology

[0004] At present, there is still no unified standard for the classification of the large deformation of the surrounding rock of the tunnel. The classification scheme is mostly divided into 3 or 5 grades according to a single index, and the classification index is mostly the strength-stress ratio or its equivalent form, which is too simple

Among them, the invention patent applications with application numbers 201811170774.3, 201810245461.3, and 201810228740.9 respectively proposed three methods for identifying large deformations of surrounding rocks, but they are all evaluations during construction and the identification indicators are relatively simple, so they have a large impact on surrounding rocks during the survey and design stage. Deformation evaluation and grading guidance have limited significance

On the one hand, in the actual survey and design stage, it is extremely difficult to accurately obtain the in-situ parameters of rock and soil mass and ground stress, and it is difficult to operate according to the existing commonly used strength-stress ratio classification standards, and the reliability is not high, and the randomness is large

On the other hand, it has been found through research that the occurrence of large deformation disasters in surrounding rocks is closely related to factors such as lithology and rock mass integrity, in-situ stress and faults, and is also affected by the development of groundwater, the angle between the rock stratum direction and the tunnel axis, and the rock strata. Due to the important influence of factors such as inclination angle, the existing large deformation classification method of tunnel surrounding rock does not take into account the important factors that affect the large deformation of surrounding rock, such as groundwater, rock formation and other factors, so the classification accuracy is low

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