Abstract
Rock burst is a common tunnel and mine dynamic disaster, especially for deep buried tunnels, which often leads to tunnel construction delay and even induces tunnel collapse and subsidence of strata. Rock drilling is one of the effective pressure relief methods to prevent these disasters. In order to study the influence of borehole diameter on rock mass pressure relief effect, indoor acoustic emission characteristics and numerical simulation of rock samples with different borehole diameter were studied. The research result shows that with the increase in borehole diameter, the effect of borehole pressure relief is better. Different borehole diameters do not change the overall trend of acoustic emission evolution, but it will lead to different acoustic emission count characteristics of rock damage and failure, especially the maximum acoustic emission count characteristics and corresponding strain values. The existence of drilling will lead to the failure stress of rock in advance. Moreover, the existence of drilling causes a great change in the failure mode of the specimen.
Highlights
Rock burst is a common tunnel and mine dynamic disaster, especially for deep buried tunnels, which often leads to tunnel construction delay and even induced tunnel collapse and subsidence of strata [1,2,3,4]. erefore, the control and research of tunnel rock burst are hot and difficult topics
Krajcinovic and Silva [7] through the experimental test studied the diameter and spacing of drilling hole on the pressure relief effect, and the research result shows that the pressure relief effect is good when the hole diameter is 300 mm and the hole spacing is 1.5 m–2.0 m; if the hole spacing is increased to 3 m, the pressure relief effect is reduced
Zhai et al [8] thought that large-diameter drilling is more suitable for large area stress relief. e research results of Jia et al [11] showed that the stress release caused by crack propagation and penetration around the borehole is the fundamental reason for the pressure relief effect of the borehole, and the larger the diameter and depth of the borehole, the smaller the spacing between the boreholes, the better the pressure relief effect of the borehole
Summary
Rock burst is a common tunnel and mine dynamic disaster, especially for deep buried tunnels, which often leads to tunnel construction delay and even induced tunnel collapse and subsidence of strata [1,2,3,4]. erefore, the control and research of tunnel rock burst are hot and difficult topics. Drilling pressure relief technology is to form a weakening zone in the rock mass through drilling holes and provide release space for the accumulated energy so as to reduce the risk of rock burst. E above research analyzes the mechanism and effect of drilling pressure relief from the stress, deformation and the layout form, and characteristics of drilling, which is of great significance for engineering safety control. The current research rarely analyzes the influence of the change of borehole diameter on the pressure relief effect and failure characteristics of rock mass. The pressure relief effect of different borehole diameters on rock mass is analyzed; secondly, the acoustic emission characteristics of rock failure are analyzed; the propagation and evolution process of microcracks are analyzed, and the failure mechanism of borehole sandstone is revealed. The pressure relief effect of different borehole diameters on rock mass is analyzed; secondly, the acoustic emission characteristics of rock failure are analyzed; the propagation and evolution process of microcracks are analyzed, and the failure mechanism of borehole sandstone is revealed. e research provides certain guidance and reference for drilling pressure relief of coal and rock mass
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