干湿循环下节理砂岩细观能量演化规律研究

Study on Meso-Energy Evolution Law of Jointed Sandstone under Dry-Wet Cycle

为探究干湿循环作用下的节理砂岩的细观损伤劣化规律,采用颗粒流软件开展了节理砂岩细观数值模拟,研究了不同干湿循环下节理砂岩的细观力学特性和能量演化机制。研究表明:随着干湿循环次数的增大,颗粒间的接触力和平行黏结力最大值呈线性递减规律;干湿循环下节理砂岩裂纹演化主要经历缓慢增加、均匀增加、阶梯增加及突变增加4个阶段,且裂纹数目(总裂纹、拉伸裂纹及剪切裂纹)与干湿循环次数呈正相关;细观边界能、平行黏结应变能及线性黏结应变能随干湿循环次数的增加呈逐渐减小趋势,节理砂岩中耗散能与微裂纹数大致呈正相关;干湿循环作用导致颗粒间抗断裂能力弱化,使岩样能量储存能力降低,这是造成节理砂岩干湿损伤劣化的能量机制。

In order to explore the meso damage and degradation law of jointed sandstone under the drywet cycles,the particle flow software was used to carry out the meso numerical simulation of jointed sandstone,and the meso mechanical properties and energy evolution mechanism of jointed sandstone under different drywet cycles were studied.The results show that the contact force between particles and the maximum value of parallel adhesion force decrease linearly with the increase of the number of dry-wet cycles;The crack evolution of jointed sandstone under dry-wet cycle mainly experienced four stages:slow increase,uniform increase,step increase and abrupt increase,and the number of cracks(total cracks,tensile cracks and shear cracks)was positively correlated with dry-wet cycles;The meso boundary energy,parallel cohesive strain energy and linear cohesive strain energy decrease gradually with the increase of dry-wet cycles.The dissipation energy in jointed sandstone is positively correlated with the number of microcracks;The dry-wet cycles action leads to the weakening of the fracture resistance between particles and the reduction of the energy storage capacity of rock samples,which is the energy mechanism that causes the dry-wet damage and deterioration of jointed sandstone.