Numerical Simulation Study On The Crack Propagation Of The Cement Mortar Block Under Explosion Load

With the development of society,concrete has become the main raw material for urban construction,road construction and other fields,it has a wide prospect of application.But the study of concrete under static load is very more,the dynamic load is very less,especially under explosion load,the rock crack propagation is more complex,the precise analysis and study are very little.Blasting technology has been widely used in various fields,the direction and degree of rock breakage can be controlled very well by study the crack propagation of concrete under explosion load.Concrete is composed of different degree of aggregate,and poor uniformity,the study on the breaking condition of the concrete under dynamic load is very difficult.This paper uses the relative uniformity of cement mortar block instead of concrete,the study on the crack propagation of the cement mortar block under explosion load,block crack extension,Especially in special blasting such as smooth blasting,pre-splitting blasting.It can control the direction of blasting and rock crack development trend very well,and provide a certain engineering blasting.The method of using the HX-3 high-speed camera shoot the process that different doses of explosive blast crack in cement mortar block,the damage of concrete under blasting gas,and understanding the breakage mechanism of the block through the experiment.Using oscilloscope measure the crack propagation time of a certain distance on the block surface,crack propagation velocity is obtained by dealing with the data.By ANSYS LS-DYNA finite element software to simulate the process of the explosion stress wave in the cement mortar block,and the block damage,the experiment results compared with the simulation results,the following conclusions:(1)It can be concluded that when the explosive is exploded in the test block,the crack propagation rate is faster with the increase of the dose,and the crack propagation is mainly reflected by stretching,and the effect of propagation is more obvious by using the electrical measuring method.(2)Block under the explosion load,the crack propagation process is the explosion stress forms the micro cracks around the blast hole,blasting raw gas increase the crack propagation in the micro crack,explosion stress forms the reflection tensile stress increasing crack extension again in the boundary.Crack propagation process mainly has two parts.First it is explosion stress,reflecting tensile stress and critical raw gas form a flaw,second other cracks are the explosion stress,reflecting tensile stress,explosive gas and the process that the first crack produces the circular tensile stress combined actions.The first crack expends a lot of energy.and Produces circumferential tensile stress.Therefore,other crack propagation velocity is a few faster than the first crack.(3)The experiment was simulated by using the JHC concrete model in ANSYS software,the simulation results compared with the experimental results concluded that JHC damage model can simulate the explosion stress wave propagation,the stress size,the damage degree,the degree of stress and damage can show the fragmentation of the block.The experimental results and simulation results are basically identical,it can descript the block crack propagation process and the breaking condition of the block.