Analysis of Impact Tendency and Sensitivity of Fractured Rock with Different Crack Arrest Measures

Abstract

Crack propagation leads to rock instability and failure, which seriously influence the safe and efficient operation of coal mines. According to the characteristics of fracture development and expansion, this paper takes a fractured rock with different crack numbers as the research background and studies the effects of the grouted arrest measure, anchored crack arrest measure, and grouted anchored arrest measure on the mechanical properties, energy evolution, crack expansion, and progressive instability of the fractured rock. The sensitivity of different crack arrest measures to the peak strength, elastic modulus, total crack number, and impact tendency of the fractured rock are analyzed based on the sensitive percentage. The experimental results show that the more cracks in the rock, the greater the increase of peak stress of grouted rock and grouted anchored rock, and the smaller the increase of peak stress of anchored fractured rock. With the increase of the crack number, the total crack number in anchored fractured rock specimens gradually decrease, the total crack number in grouted rocks, and grouted anchored rock specimens gradually increase. The anchored fractured rock with more cracks produces a lower total crack number when it is destroyed. The grouted rock and grouted anchored rock with more cracks produce a higher total crack number when it is destroyed. The pre-peak energy of anchored single-fractured rock is larger, the pre-peak energy of grouting multi-fractured rock is larger, and the grouted rock has a strong impact tendency. The grouted arrest measure is an important sensitive parameter to the impact energy index; the anchored crack arrest measure is the primary sensitive parameter to the peak stress, elastic modulus, and total crack number; and the grouted anchored arrest measure is an important sensitive parameter to the elastic modulus. The research results of this paper provide some guidance on the selection of crack arrest parameters and scheme design in practical rock engineering.

Experimental Investigation on the Influence of Temperature on Coal and Gas Outbursts

“…When an outburst occurs, the rock/coal/gas system transforms from a stable to an unstable state with the release of a significant volume of gas over the duration of the outburst [6][7][8][9][10]. The occurrence of this phenomenon often leads to the destruction of tunnels or even human casualties [11][12][13]. Domestic and overseas studies have reported that the burst tendency is an inherent attribute of the rock and an internal factor in the occurrence of rock bursts [14].…”

Measurement and Classification Criteria of Strength Decrease Rate and Brittleness Indicator Index for Rockburst Proneness Evaluation of Hard Rocks

“…The measurement methods and grade classification criteria of different bursting indexes have become the hot research field [26]. Most bursting indexes are defined from the perspective of energy, such as the strain energy storage index W ET [27], the peak-strength strain energy storage index W P ET , the peak-strength energy impact index A CF [28] and the residual elastic energy index A EF [29,30]. Likewise, there are also many non-energy bursting indexes, such as the modified brittleness index BIM, the deformation brittleness index K u [31], the decrease module index DMI [32], the brittleness indicator index B [33], and the strength decrease rate index SDR [34].…”