水力耦合条件下预制节理砂岩裂纹扩展和能量演化细观数值模拟

Mesoscopic Numerical Simulation on Crack Expansion and Energy Evolution of Sandstone With Prefabricated Joint Under Hydro-Mechanical Coupling Condition

为了研究水力耦合作用条件下预制节理砂岩三轴压缩裂纹扩展和能量演化规律,建立预制节理砂岩流固耦合数值模型,得到预制节理砂岩应力-应变曲线.通过分析平行黏结破碎演化过程,获得不同预制节理角度下微裂纹发育规律.基于颗粒流程序(PFC)离散元能量追踪体系,研究得到各细观能量变化响应和能量耗散与转换规律.分析结果表明:预制节理角度越大,试样峰值强度越大,侧向变形和轴向变形峰值应变先增大后减小,在预制节理角度为60°时取得最大值;平行黏结破碎起始于预制节理,进而扩展贯通,次生黏结破碎带始于节理面直至贯穿试样边界;试样的黏结能峰值和应变能峰值均与预制节理角度成正比,黏结强度峰值应变和应变能峰值应变与预制节理角度成反比;耗散能主要表现为摩擦作用,整个加载过程中弹性应变能吸收率最大.

In order to study the crack expansion and the energy evolution from the prefabricated joint sandstones under the triaxial compression test,a numerical model of prefabricated joint sandstone combining with fluid-solid coupling was established,and the stress-strain curves of prefabricated joint sandstone was obtained.The crack development under different prefabricated angles was found by analyzing the evolution process of parallel bond rupture.Based on energy tracking system from particle flow code（PFC）,the microscopic energy variation and relation curves of dissipated energy were presented.The results indicate that with the increase of prefabricated joint angle,the peak strength of the sample increases,the peak strains in lateral and axial directions initially increase and then decrease,and reach maximum at 60°.The rupture of parallel bond extends from prefabricated joint,and then cuts through specimen;the secondary bond rupture begins from the joint plane,then cuts through the sample boundary.The bond strength peak and strain energy peak of samples are proportional to the prefabricated joint angle,the bond strength peak strain and strain energy peak strain of samples are inversely proportional to the prefabricated joint angle.The main dissipation energy is the friction action,and the elastic strain energy absorption is the maximum during the whole loading process.