Numerical Simulation Of The Effect Of Anomalously Low Friction Of Deep Rock Masses Based On FLAC-3D

With the increase of mining depth, the dynamic behavior of rock mass shows new features and new phenomena, and the mechanism of anomalously low friction effect of deep rock masses is one of the key scientific issues. Due to the anomalously low friction effect, equilibrium relationship and constraint conditions of rock mass are destroyed, and rock mass prone to translation and rotation, which induces dynamic disaster such as rock burst, coal burst and poses a huge threat to mining safety. Therefore, it is of great value and practical significance to study the anomalously low friction effect of deep rock mass to mining safety and coal rock dynamic disaster's forecasting and prevention.Using granite block model, anomalously low friction effect of deep rock masses is simulated by FLAC-3D numerical software under two kinds of load conditions, including the interaction of vertical impact and lateral static and the interaction of vertical impact and lateral impact. The horizontal displacement and normal force evolution law of work block of model are calculated, and distribution characteristics of vertical and horizontal stress of block model are also calculated.The results show that:under two kinds of load conditions, with the increase of the amplitude of the vertical impact load, vertical force amplitude and horizontal residual displacement of working block increase correspondingly, which lead to the anomalously low friction effect occurring, and it is becoming more and more obvious. With the increase of impact load frequency, attenuation speed of the normal force of contact surface of work block increase, and the horizontal residual displacement is reduced, so that the anomalously low friction effect of deep rock masses weaken; With the increase of mining depth, vertical force amplitude and horizontal residual displacement of working block are gradually increasing, anomalously low friction effect is becoming more and more obvious. When vertical impact and horizontal impact act on the granite block model, either horizontal impact load before or after vertical impact load applied to the model, the normal force amplitude range are increased, and the anomalously low friction effect tends to be more significantly. The horizontal residual displacement caused by the horizontal impact load is much greater than the horizontal residual displacement caused by the vertical impact load. Therefore, the horizontal impact of parallel direction of contact surface is the main influence factors of the effect of anomalously low friction of deep rock masses.