Theoretical Analysis Of Key Block Movement Of Cave Surrounding Rock Under Stress Wave

With the increasing tightening of aboveground exploitable space,the excavation and utilization of underground space has become an effective means to solve the problem of land resources.Rock mass is a complex medium composed of structural surfaces and structural bodies.The study shows that the stability of the surrounding rock is mainly controlled by the properties of the structural surface.After the excavation of the underground cave,the original static balance state of the surrounding rock is broken.When the air surface exists,the rock block cut by the structural surface may collapse or fall.The collapse of one block provides space for other moving blocks to fall,which may trigger a series of blocks and eventually cause the collapse of the entire chamber,affecting the safety of the chamber.Therefore,the stability analysis of the local mass in the surrounding rock is of great research significance.However,the traditional theoretical analysis method adopts the equivalent static method for analyzing the dynamics,and the disadvantage is that the sliding instability process of the block cannot be analyzed.Based on the above background,the dynamic response of the mass under the action of stress wave.This paper summarizes the calculation method involved in the theoretical analysis,and then obtains the formula of the response of the block motion.The accuracy of the theoretical calculation method is verified by comparing the obtained theoretical calculation results with the numerical simulation results.Then,the parameters of the mass size,the incident wave frequency,the joint stiffness and the pressure of the surrounding mass were analyzed.By numerical analysis of the method,the motion response of different shapes were compared,and the trapezoidal blocks were most likely to drop.The parameter analysis of joint inclination angle,mass size,incident wave frequency,joint stiffness and surrounding rock pressure shows the influence of each parameter change on the sliding law of parallelogram and trapezoidal mass.After the above analysis,the innovative results are as follows:(1)Based on the theoretical analysis method of stress wave propagation,the deduction of the motion equation of the key block under the action of stress wave was carried out,the Matlab program was written to calculate the motion response of the block,and the influence of the block size,incident wave frequency,joint stiffness and surrounding rock pressure on the vertical slide law of the key block was analyzed.(2)Based on the numerical simulation of UDEC software,the dynamic response rules of the key block shape as parallelogram and trapezoid under the action of stress waves are further analyzed.The results show that the incident wave frequency has the most significant influence on the key block movement compared with other influencing factors.