Abstract
For ensuring safety and efficiency during the construction of deep engineering, it is essential to explore the failure mode of the surrounding rock mass under dynamic disturbance and high geo-stress. We conducted true triaxial load tests for rock-like material with a preexisting circular hole, and monitored the acoustic emission (AE) signal during the whole test. The result demonstrates the evolution characteristics of damage and failure mode with different cyclic dynamic load amplitudes and intermediate principal stress. With the increase in cyclic dynamic load amplitude or the decrease in intermediate principal stress, the failure source mainly occurs at the two horizontal side walls of the surrounding rock where the failure patterns change from the slabbing to wall caving and, finally, to rockburst. The former failure mode can actually serve as an important precursor for the latter. Based on such mechanisms, the precursor can be indirectly detected in forms of AE signal released by microcracking. The research can provide a reliable guidance for the rock stability control and faithfully forecasting the larger-scale failure during the excavation of deep circular cavern.
Highlights
Deep-earth resource exploitation is very popular in recent years since the mineral resources in the shallow have been excessively depleted and, nowadays, the demand for mineral resources is increasing
In order to compare the responses of the surrounding rock to cyclic dynamic load amplitude, the failure modes under a certain number of cycles should be targeted for the analysis
The results show that the acoustic emission (AE) activity at the later period of cyclic dynamic loading phase become active when the cyclic dynamic load amplitude gradually increases from 4 MPa to 6 MPa and, to 8 MPa
Summary
Deep-earth resource exploitation is very popular in recent years since the mineral resources in the shallow have been excessively depleted and, nowadays, the demand for mineral resources is increasing. There are three methods to study the damage and failure characteristics of surrounding rock in deep engineering: theoretical analysis, numerical simulation, and laboratory or in situ tests. Because theoretical research and numerical analysis cannot completely simulate the actual construction scheme and engineering environment, the study of deformation and failure characteristics of the surrounding rock still needs to be supported by in situ and laboratory tests. Such experimental configurations aim at simulating the deformation and damage behaviors in the surrounding rocks of the deep circular tunnels.
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