Method for predicting toppling instability of layered rock mass underground engineering high side wall in excavation process

Abstract

The invention provides a method for predicting toppling instability of a high side wall of layered rock mass underground engineering in an excavation process. According to the invention, the method comprises the steps: employing the microseism monitoring technology for capturing a microseism event in a high side wall area in the excavation process of the layered rock mass underground engineering;embedding rock mass degradation information reflected by the micro-seismic data into the numerical calculation model to realize prediction of excavation surrounding rock mechanical response; then, performing deducing by adopting a cantilever beam theory and a sudden change theory to obtain an instability criterion of toppling deformation of the rock stratum of the anti-toppling structure; dispersing the upper edge and the lower edge of the rock stratum with the potential toppling instability risk on the research profile of the instability risk area into a plurality of small sections, extracting stress values corresponding to end points of the small sections, and substituting the stress values into an instability criterion formula to predict the toppling deformation stability of the anti-toppling high side wall. The rock stratum toppling instability criterion formula used in the method fully considers the influence of the secondary stress field of the surrounding rock of the undergroundengineering, and the accuracy of toppling deformation instability of the high side wall of the layered rock underground engineering can be improved.

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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