Study of influences of rock hardness on crack evolution rule under hydraulic fracturing

Abstract

In order to study the crack evolution rules of hydraulic fracturing rock with different hardness, a numerical model of hydraulic fracturing rock was established. It explored the expansion length, expansion width, propagation rate of crack and initiation pressure of hydraulic fracturing different hardness rocks. The results show that the expansion length, the propagation rate along length and the initiation pressure of crack were positively correlated with the rock hardness, and the expansion width and propagation rate along width were negatively correlated with the rock hardness. In addition, considering the effect of in-situ stress difference, it took granite as an example, and studied the effect of in-situ stress difference on crack propagation. It is found that as the in-situ stress difference increases, the initiation pressure of the crack decreases, and the crack expansion length and the propagation rate along length shows a linear increase, but it has little effect on the crack expansion width. The results can provide theoretical references for improving the application of hydraulic fracturing technology in hard rock excavation, such as the coal roadway excavation, the tunnel excavation and so on.

An ultrafast time-resolution method based on picosecond pulsed laser for determining rock fracture toughness at multipoint during the crack propagation

“…For example, effective rock fracture may improve the ore recovery ratio through effective separation of minerals along their grain boundaries in mineral processing 32 – 35 . Jialiang Liu et al studied the crack evolution rules of hydraulic fracturing rock with different hardness 36 . By conducting a series of calculation analyses of the crack rheological fracture under different hydraulic pressures, Yanlin Zhao et al found that wing crack propagation can be divided into two parts: the transient crack propagation at very high velocity and subcritical crack propagation at extreme low velocity 37 .…”

Investigation into Macro- and Microcrack Propagation Mechanism of Red Sandstone under Different Confining Pressures Using 3D Numerical Simulation and CT Verification

“…The distribution and expansion of its fissures directly affect mining safety, such as underground water inrush and roof failure which are all developed and evolved from cracks and other weak surfaces [8,9]. In underground mining, the development of fissures is one of the major causes leading to the destruction of rock projects [10][11][12]. Understanding the crack propagation mechanism can provide a feasible basis for engineering safety design.…”