A Numerical Simulation Of Rock Failure In Three Dimension

Social development while resource shortage makes human being increase the use of underground space.Excavation has been one of important ways.However,excavation break the original balance of rock,leading stress redistribution.Consequently,the rock explodes,which brings the threat to life and property.Therefore,the research of rock burst mechanism is meaningful for reducing or avoiding rock explosion.Considering confining pressure,this paper studies the failure characteristics on the condition that remove the axial load in a very short time.In order to get closer to the real state of rock,the study was divided into two parts,including loading and unloading.In loading phases,the way of restart was used.While in unloading,this paper studied three ways,such as slow-fast,fast-slow and straight,form the perspective of the max stress,the start time of rock break and the lasting time of destruction.Finally,it showed the straight way was better.On the basic of it,the paper had studied stress evolution,redistribution,the mechanism of element failure at a micro level with changing confining pressure.The following conclusions can be drawn from the numerical simulations.Notwithstanding the maximum principal stress and the occurrence of broken of the straight unloading way stays middle,duration is the longest.To the phase of stress initialization,the trend of stresses is the same,and all of them stay desired point in lower confining pressures.In higher confining pressures,however,they settle at different values,with the occurrence of stress circle.When the sample is in lower confining pressures,it happens to be tension failure,with the phenomenon of laminar paralleling to the bottom.Oppositely,both tension and compression failures occur in higher confining pressures.To the pressed elements,when the confining pressure is higher,the element changes from tensile to compressive stress before the final rupture.While the value is much higher,the element has always been in a state of compression,but there is a sudden increase before the destruction.