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为了研究砂岩的强度特性以及破坏规律,利用分离式Hopkinson装置对砂岩巴西圆盘进行不同冲击速度的动态劈裂试验,并利用三维非线性动力学分析软件LS-DYNA模拟这一劈裂过程。通过对试验所得应力应变曲线与模拟所得应力应变曲线的对比,确定数值模型的有效性。结合试验结果以及模拟结果可以得出,总体上砂岩的动态抗拉强度随着平均应变率的增大而增大,但并不是线性关系,而是当平均应变率低于某一值时,动态抗拉强度随着平均应变率的增加急剧增大,当平均应变率高于这一值时,动态抗拉强度随着平均应变率的增加而缓慢的增加;在动态劈裂过程中,砂岩巴西圆盘的破坏并不都是从中心位置起裂的,初始起裂位置与平均应变率的大小有关,当平均应变率小于某一值时,初始起裂位置在靠近入射杆一端,当平均应变率大于某一值时,初始起裂位置在靠近透射杆一端;砂岩试件的总体破坏顺序是由靠近入射杆端或者靠近透射杆端向中间位置扩展,同时由试件表面向内部扩展,最终上下表面导通,试件被劈裂成两半。
In order to study the strength characteristics of sandstone and the failure rules, the dynamic Hopkinson apparatus was used to test the dynamic splitting of sand disks with different impact velocities. The 3D nonlinear dynamic analysis software LS-DYNA was used to simulate the splitting process. The validity of the numerical model is confirmed by comparing the stress-strain curve with the stress-strain curve obtained from the simulation. According to the test results and the simulation results, it can be concluded that the dynamic tensile strength of sandstone generally increases with the increase of average strain rate, but not linearly. However, when the average strain rate is lower than a certain value, the dynamic The tensile strength increases sharply with the increase of the average strain rate. When the average strain rate is higher than this value, the dynamic tensile strength increases slowly with the increase of the average strain rate. During the dynamic splitting, sandstone Brazil The failure of the disc does not all start from the center. The initial initiation position is related to the average strain rate. When the average strain rate is less than a certain value, the initial initiation position is near the end of the rod. When the average strain When the rate is greater than a certain value, the initial rupture position is close to the end of the transmission rod. The overall failure sequence of the sandstone specimen extends from near the end of the rod or near the end of the rod to an intermediate position, The upper and lower surfaces are conductive, and the test piece is split into two halves.