不同内径圆环砂岩试件温水耦合动态劈裂力学试验研究

Mechanical test study on thermo-water coupled dynamic splitting of annular sandstone specimens with different inner diameters

煤矿巷道围岩经常处于地下水和温度共同作用环境中。由于岩石动抗拉强度远小于其动抗压强度,当受到掘进爆破等动载作用时岩体破坏往往取决于动抗拉强度,温水耦合岩石在动荷载扰动下动态抗拉力学性能值得深入研究。对不同内径圆环砂岩试件(外径50 mm,内径0~25 mm)进行温水耦合作用,开展X射线衍射和扫描电子显微镜试验,并利用霍普金森压杆试验装置进行动态劈裂力学特性试验研究。结果表明:温水耦合作用使砂岩试件产生损伤劣化,基本物理参数发生变化,动力学性能呈现出弱化现象;相同加载条件下,圆环砂岩试件内径增大,试件更易发生张拉破坏;劈裂后的半圆环发生了挤压断裂;相同内径时,温水耦合作用砂岩试件碎块更加明显;从能量耗散角度对试件破碎形态进行分析。

Surrounding rock of coal mine tunnels is often in an environment where groundwater and temperature interact together.Due to the fact of dynamic tensile strength of rocks is much smaller than its dynamic compressive strength,rock failure often depends on its dynamic tensile strength when subjected to dynamic load,such as excavation blasting.Therefore,dynamic tensile mechanical properties of thermo-water coupled rock under dynamic load disturbances are worthy of in-depth study.Here,thermo-water coupled tests were conducted for annular sandstone specimens with outer diameter of 50 mm and different inner diameters of 0-25 mm.X-ray diffraction(XRD)and scanning electron microscopy(SEM)tests were conducted for these specimens.Their dynamic splitting mechanical characteristics were also studied using split Hopkinson pressure bar(SHPB)test device.The results showed that thermo-water interaction causes damage and deterioration of sandstone specimens,their basic physical parameters change and their dynamic performance is weakened;under the same loading conditions,inner diameters of annular sandstone specimens increase,they are easier to have tensile failure;after splitting,semi-circular rings undergo compression fracture;when inner diameter is the same,the thermo-water interaction makes fragmentation of sandstone specimens more obvious;fracture morphologies of specimens are analyzed from the perspective of energy dissipation.