裂隙岩体渗流–损伤–断裂耦合模型及其应用

COUPLING MODEL OF SEEPAGE-DAMAGE-FRACTURE IN FRACTURED ROCK MASSES AND ITS APPLICATION

从岩体结构力学和细观损伤力学的角度出发,根据裂隙发育与工程尺度的关系,建立合理且适用的裂隙岩体渗流–损伤–断裂耦合数学模型,该模型能真实反映渗流场与应力场耦合作用下裂隙岩体的损伤演化特性,并能模拟由于渗透压的存在和变化引起的拟连续岩体内翼形裂纹的开裂、扩展和贯通等损伤演化特性和高序次贯通裂隙的张开、闭合。建立考虑渗透压力的三维含水裂隙岩体弹塑性断裂损伤本构方程和损伤应力状态作用下流体渗流方程,给出该数学模型的求解策略与方法,开发裂隙岩体渗流–损伤–断裂耦合分析的的三维有限元计算程序DSDFC.for。该计算程序能模拟岩体分步开挖、应力和渗流边界的动态变化,对裂隙岸坡蓄水加载过程进行渗流–损伤–断裂耦合分析,发现水库蓄水后岸坡山体的竖向抬升,随水位上升岸坡破损区增大,断层塑性区向岸坡深部扩展,与裂隙渗流比较,拟连续岩体渗流滞后。

From the aspects of structural mechanics of rock mass and meso-damage mechanics, a practical mathematical model of seepage-damage-fracture coupling is established based on the relation between the dimensions of fractures and the engineering scale. It can reveal damage evolvement characteristics of fractured rock masses under coupling analysis of seepage field and stress field; and it can also simulate the damage evolvement of fractured rock masses, which is led by wing-crack generation, propagation and coalescence in quasi-continuous rock masses because of the existence and change of seepage pressure. Three-dimensional elastoplastic damage-fracture constitutive relation and fluid seepage constitutive equation under damage stress state were established. Strategy and methods to solve this mathematical model are also presented. A three-dimensional finite element codes DSDFC.for for analysis of coupled seepage-damage-fracture processes in fractured rock masses were developed. The program can simulate excavation of rock masses and the dynamic change of boundaries of stress and seepage step by step. The detailed 3D numerical simulation for the fractured rock slope of a reservoir during the rising of water level in reservoir is given. The result shows that the lifting deformation of valley of the reservoir is achieved; the damage and plastic areas in slope increases with the rising of water level and the plastic area in faults are enlarged. Compared with discrete fractured medium, the hysteresis flow effect in quasi-continuous rock masses is remarkable.