Abstract
In order to investigate the dynamic mechanical properties of the fractured rocks reinforced with different slurries, the prefractured and grouted sandy mudstone specimens were tested on a Split Hopkinson Pressure Bar (SHPB), and their dynamic failure processes were shot via a high-speed camera. The test results showed that under dynamic loading, grouting reinforcement can relieve the rock failure at the fracture part. With the increase of the impact speed, the dynamic specific strength of the modified epoxy resin grouting increases from 0.85 to 1.01, and its specific strain rate increases from 1.09 to 1.04; the dynamic specific strength and specific strain rate of cement slurry grouting increase from 1.78 to 0.95 and from 0.60 to 0.98, respectively. As a whole, the specimen reaches or approaches the dynamic parameters of the intact rock specimen after grouting repair, the stability of the rock reinforced by modified epoxy resin grouting is superior to that of the rock reinforced by cement slurry grouting, and the latter can acquire high dynamic strength under low-speed impact. The improved damage-type Zhuwangtang (ZWT) model can be used to describe the dynamic mechanical behaviors of the fractured rocks reinforced by grouting very well.
Highlights
During the deep coal mining and tunneling process, the mining activity breaks the original mechanical equilibrium
An impact test of fractured rock masses reinforced by different grouting materials was carried out under different strain rates on a Split Hopkinson Pressure Bar (SHPB), and their dynamic failure process was captured via a high-speed camera. e results contributed to understanding of the dynamic failure laws of fractured surrounding rocks, revealed the impact resistance of fractured rock masses reinforced with different slurries under different strain rates, and provided a reference for the grouting reinforcement engineering for fractured rock mass
With the impact speed increased, the specimen filled with epoxy resin showed a gradually declining specific strain rate, which was approaching 1, and the specific strain rate of the specimen filled with cement slurry gradually rose and approximated to 1. e specific strain rate of the specimen filled with cement slurry seemed to have stronger sensitivity to the impact speed, and the change was more evident, but the specific strain rate of the specimen filled with epoxy resin
Summary
During the deep coal mining and tunneling process, the mining activity breaks the original mechanical equilibrium. E range of dynamic load strain rate is large and the impact strength is high, which will usually result in secondary failure of fractured rock mass after grouting reinforcement. It is urgent to explore into the impact resistance and failure laws of fractured rock mass after grouting reinforcement, and studying the dynamic characteristics of fractured rock masses reinforced by different slurries under different strain rates will be of great realistic significance. E results contributed to understanding of the dynamic failure laws of fractured surrounding rocks, revealed the impact resistance of fractured rock masses reinforced with different slurries under different strain rates, and provided a reference for the grouting reinforcement engineering for fractured rock mass An impact test of fractured rock masses reinforced by different grouting materials was carried out under different strain rates on a Split Hopkinson Pressure Bar (SHPB), and their dynamic failure process was captured via a high-speed camera. e results contributed to understanding of the dynamic failure laws of fractured surrounding rocks, revealed the impact resistance of fractured rock masses reinforced with different slurries under different strain rates, and provided a reference for the grouting reinforcement engineering for fractured rock mass
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