基于统计强度理论的破裂岩体本构模型研究

借助损伤力学思想,基于统计强度理论,提出一种适用于深部工程破裂区破裂岩体的本构模型建立方法,并通过室内试验和数值试验进行了验证。将破裂岩体划分为无数微元立方体,微元立方体的强度与岩石破裂程度有关,且各立方体强度随机分布,故可用强度反映破裂岩体的破裂程度,据此提出一种破裂岩体本构模型建立方法。其中,根据岩石破裂面间的摩擦力做功等于材料破裂后释放的应变能,得到从力学角度定义的岩石破裂程度变量;另外,假定微元立方体强度分布服从Weibull分布,应力水平满足Hoek-Brown准则。利用泥质砂岩破裂岩体典型三轴试验结果,建立泥质砂岩破裂岩体本构模型,并进行了验证,结果表明模型计算曲线与试验曲线吻合度较好。利用离散元软件PFC进行了补充数值试验验证研究,证明了泥质砂岩破裂岩体理论模型的良好计算效果,进而证明提出的本构模型建立方法的可行性。

Study on constitutive model of fractured rock mass based on statistical strength theory

With the aid of damage mechanics and on the basis of statistical strength theory, a method for establishing the constitutive model of deep fractured rock mass is proposed and verified by laboratory and numerical tests. The fractured rock mass is divided into numerous micro-cubes. The strength of micro-cubes is related to the fracture degree and the strength of each micro-cube is randomly distributed. Thus the strength can be used to reflect the fracture degree of the rock mass. Among them, based on the fact that the work done by friction between fracture surfaces is equal to the strain energy released after the material fracture, the rock fracture degree variable defined from the mechanical point of view is obtained. In addition, it is assumed that the strength distribution of micro-cubes obeys the Weibull distribution and the stress behavior satisfies Hoek-Brown criterion. The constitutive model of fractured argillaceous sandstone rock mass is then established and verified based on typical triaxial test results of fractured rock samples. The results show that the calculated curve from theoretical model is in good agreement with the test results. At last, a supplementary numerical test is carried out using discrete element software PFC, which further proves the good calculation performance of theoretical model for argillaceous sandstone and the feasibility of the constitutive model establishing method proposed in this paper.