花岗岩热破裂裂隙动态演化特性数值模拟研究

Numerical simulation of dynamic evolution characteristics of thermal fracture in granite

为揭示不同压力条件下花岗岩热破裂裂隙演化规律,采用数值计算方法,结合细观损伤理论,建立了岩石热-弹性本构模型,提出了适用于Comsol Multiphysics数值计算软件的矿物颗粒形态提取技术。开展了静水压力及单轴压力下花岗岩热破裂数值模拟研究,分析了拉伸和剪切裂隙动态发育过程。研究结果表明:花岗岩内矿物热破裂顺序依赖于各自的力学特性、强度,3种矿物的破裂顺序为云母、长石、石英,热破裂裂隙网络由拉伸裂隙和剪切裂隙组成,拉伸裂隙的发育主导了裂缝网络形成。裂隙演化可划分为3个阶段:微裂隙萌生阶段、裂隙爆发阶段、稳定增长阶段。热破裂阈值受最小主应力控制,单轴压力对阈值的影响较小,受静水压力的影响较大。静水压力下裂隙发育没有明显的方向性,单轴压力压扩展方向垂直于最小主应力,压力越大方向性越明显。

To investigate the evolution of thermal fracture cracks in granite under varying pressure conditions,numerical methods were employed in conjunction with microscopic damage theory to establish a rock thermal elastic constitutive model.A mineral particle morphology extraction technique tailored for Comsol Multiphysics software was introduced,facilitating numerical simulations on thermal fractures in granite under static water and uniaxial pressures.The dynamic progression of tensile and shear cracks was analyzed.Findings suggest that the sequence of thermal fractures in granite minerals is contingent upon their individual mechanical properties and strength,with the rupture sequence of the three minerals is mica,feldspar and quartz.The thermal fracture network comprises both tensile and shear fractures,with tensile fractures predominantly shaping the network.Fracture evolution unfolds in three stages:micro-fracture initiation,fracture eruption,and stable growth.The thermal fracture threshold is governed by the minimum principal stress,with uniaxial pressure exerting a minor influence compared to hydrostatic pressure.Fracture development under hydrostatic pressure lacks clear directionality.Uniaxial pressure propagates perpendicular to the minimum principal stress,with directionality becoming more pronounced as pressure increases.