Underground pumped storage power plant (UPSP) is an innovative concept for space recycling of abandoned mines. Its realization requires better understanding of the dynamic performance and durability of reservoir rock. This paper conducted ultrasonic detection, split Hopkinson pressure bar (SHPB) impact, mercury intrusion porosimetry (MIP), and backscatter electron observation (BSE) tests to investigate the dynamical behaviour and microstructure of sandstone with cyclical dry-wet damage. A coupling FEM-DEM model was constructed for reappearing mesoscopic structure damage. The results show that dry-wet cycles decrease the dynamic compressive strength (DCS) with a maximum reduction of 39.40%, the elastic limit strength is reduced from 41.75 to 25.62 MPa. The sieved fragments obtain the highest crack growth rate during the 23rd dry-wet cycle with a predictable life of 25 cycles for each rock particle. The pore fractal features of the macropores and micro-meso pores show great differences between the early and late cycles, which verifies the computational statistics analysis of particle deterioration. The numerical results show that the failure patterns are governed by the strain in pre-peak stage and the shear cracks are dominant. The dry-wet cycles reduce the energy transfer efficiency and lead to the discretization of force chain and crack fields.

中文翻译：

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干湿循环对砂岩动态特性和微观结构的影响：实验和建模


地下抽水蓄能电站（UPSP）是废弃矿山空间回收的创新概念。它的实现需要更好地了解储层岩石的动态性能和耐久性。本文通过超声波检测、分体式霍普金森压杆（SHPB）冲击、压汞孔隙率测定（MIP）和背散射电子观测（BSE）测试，研究了干湿循环损伤砂岩的动力学行为和微观结构。建立了再现细观结构损伤的有限元-离散元耦合模型。结果表明，干湿循环使动态压缩强度(DCS)降低，最大降低39.40%，弹性极限强度从41.75 MPa降低到25.62 MPa。筛分碎片在第 23 个干湿循环期间获得最高的裂纹扩展速率，每个岩石颗粒的预计寿命为 25 个循环。大孔隙和微细孔的孔隙分形特征在早期和后期循环中表现出较大差异，验证了颗粒劣化的计算统计分析。数值结果表明，破坏模式受峰前阶段应变控制，且剪切裂纹占主导地位。干湿循环降低了能量传递效率并导致力链和裂纹场的离散化。