Prediction method for toppling instability of high side walls in layered rock mass underground engineering during excavation

Abstract

The invention provides a method for predicting the toppling and instability of high side walls of layered rock mass underground engineering during excavation. The method utilizes microseismic monitoring technology to capture microseismic events in the high side wall area during the excavation process of layered rock mass underground engineering, and The rock mass degradation information reflected by the microseismic data is embedded in the numerical calculation model to realize the prediction of the mechanical response of the excavated surrounding rock, and then the instability criterion for the toppling deformation of the anti-dipping structure rock layer is derived by using the cantilever beam theory and the catastrophe theory, which will be in the state of failure. The upper and lower edges of rock formations with potential toppling and instability risks on the research section of the stability risk area are discrete into many small sections, and the stress values ​​corresponding to the endpoints of each small section are extracted, and substituted into the instability criterion formula to realize the toppling of the high side wall on the anti-tilt side. Prediction of deformation stability. The rock formation toppling instability criterion formula used in the method of the invention fully considers the influence of the secondary stress field of the surrounding rock of the underground engineering, and can improve the accuracy of the toppling deformation and instability of the high side wall of the layered rock mass underground engineering.

Description

technical field [0001] The invention belongs to the field of geotechnical engineering, and relates to a method for predicting the toppling instability of a layered rock mass underground engineering high side wall during excavation. Background technique [0002] my country's rapid economic development, increasing energy demand and the continuous and in-depth implementation of the "Western Development" strategy have prompted the construction of a number of large-scale traffic tunnels and hydropower underground caverns in the western mountainous areas. The wide distribution of layered rock mass makes most large-scale underground projects such as traffic tunnels or hydropower underground caverns built in this type of rock mass. Compared with other structural planes such as joints, layered rock mass has a relatively constant occurrence and better The spatial continuity also makes it easy to intersect with the entire underground engineering building, and the degree and scope of in...

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Problems solved by technology

[0003] The traditional prediction method of toppling deformation and instability is mainly aimed at layered rock slopes. The current methods for predicting the toppling deformation and instability of surrounding rock in underground caverns are all based on the research results in the field of slopes, only from the geometric point of view. The difference between the side wall and the slope of the chamber does not take into account the huge difference in the secondary stress field between the slope and the surrounding rock of the underground cavern. Especially for hydropower underground caverns with complex sections, the traditional prediction method is more is very limited in application

[0004] Although there are many studies on the stability analysis of toppling deformation and failure, most of them are aimed at layered rock slopes, and the secondary stress field of the surrounding rock of hydropower underground caverns with complex cross-section forms is unstable to the toppling deformation of high side walls. The influence effect of is not reflected in the traditional prediction model of toppling instability

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