Method for assessing risk level of hard rock burst disaster in great-depth cavern

Abstract

The invention discloses a method for assessing the risk level of a hard rock burst disaster in a great-depth cavern. The method comprises the following steps: carrying out an in-situ ground stress test; drilling a cylindrical rock sample at a ground stress test position; emitting an ultrasonic flaw detection signal to the cylindrical rock sample by using a multi-channel ultrasonic flaw detector, and calculating the crack initiation strength sigma<ci><j> (j=1, 2, 3) and damage strength sigma<cd><j> (j=1, 2, 3) of hard rock in three states; calculating equivalent crack initiation strength sigma<ci><*> and equivalent damage strength sigma<cd><*> according to the range principle; comparing rock strength to stress ratios under a gravity stress field and a tectonic stress field with the equivalent crack initiation strength sigma<ci><*> and the equivalent damage strength sigma<cd><*>, and assessing the level of the hard rock burst disaster in the great-depth cavern. The method is implementedcomprehensively by a field ground stress test, an indoor uniaxial compression test, and an ultrasonic and acoustic emission coupling system. By adopting the method, the equivalent crack initiation strength and equivalent damage strength of the hard rock and the stress-strength ratio of rock after excavation of the cavern can be obtained effectively, and the problem concerned with stability evaluation of the great-depth cavern as well as optimization of level assessment and control measures of the hard rock burst disaster is solved.

Description

technical field [0001] The invention relates to the technical field of geological exploration, in particular to a method for assessing the risk level of rockburst catastrophe in hard rock in large deep caverns, which is suitable for risk identification and prevention and control of rockburst disasters in large deep caverns mainly composed of hard and brittle rocks optimization of measures. Background technique [0002] Rockburst is the sudden release of the elastic strain energy stored in the rock mass due to the unloading of the hard and brittle surrounding rock during the excavation of underground engineering under high ground stress conditions, resulting in bursting, loosening, peeling, ejection and even throwing, etc. A dynamical instability geological disaster of destruction phenomenon. From the time of occurrence, rockbursts are divided into immediate rockbursts and time-delayed rockbursts. According to the conditions and mechanisms of occurrence, rockbursts can be d...

AI Technical Summary

Problems solved by technology

However, most of the existing evaluation indicators use empirical methods, and the value of each indicator is a fixed value or a definite limit value. For deep cavern projects with complex and variable occurrence environments and lithological characteristics, it is not reasonable. Reflect the influence of lithology, rock mass structure and external conditions on the evaluation of rockburst grade

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