厚壁圆筒花岗岩在动静耦合循环冲击作用下的动态力学特性试验研究

Experimental Study of Dynamic Mechanical Characteristics of Thick-walled Cylindrical Granite Under Dynamic and Static Coupled Cyclic Impact

为研究动静耦合循环冲击作用下厚壁圆筒花岗岩的动态力学特性,利用改进的霍普金森杆,选取不同轴向预应力对花岗岩试样进行等幅循环冲击。试验结果表明:轴向预应力为83 MPa,试件的反射波和透射波在冲击破坏时出现最大和最小峰值;不同轴向预应力对试件的动态变形模量和最大应变具有不同的影响;随轴向预应力的增大,试件的组合强度呈递增趋势,表现出一定的"强化效应"。试件在循环冲击过程中,动态强度和应变率成相反规律,表现出较好的应变率效应;轴向预应力影响着试件的破坏形态,随轴向预应力的增加,试件由剪切-拉伸混合破坏向剪切为主的剪切-拉伸破坏模式过渡。

In order to study the dynamic mechanical characteristics of thick-walled cylindrical granite under the action of dynamic and static coupled cyclic impact,an improved Hopkinson bar was used to select different axial prestresses to perform constant amplitude cyclic impact on granite samples.The test results show that,the axial prestress is 83 MPa,and the reflected wave and transmitted wave of the specimen appear the maximum and minimum peak during impact failure.Different axial prestresses have different effects on the dynamic deformation modulus and the maximum strain of the specimen.With the increase of axial prestress,the combined strength of the specimen shows an increasing trend,showing a certain"strengthening effect".In the process of cyclic impact,the dynamic strength and strain rate of the specimen are opposite,showing a good strain rate effect.The axial prestress affects the failure form of the specimen.With the increase of the prestress,the specimen transforms shear-tensile failure to shear-dominated failure mode.