岩石损伤模量分析

从能量的角度出发定义损伤变量,通过应力-应变曲线卸载段有效应力与总应力之间的假定关系,确定损伤模量的计算方法。在单轴和三轴条件下,对岩石损伤相关参数进行统计研究,重点对损伤模量进行计算和对比分析。结果表明,单轴及低围压下损伤模量基本呈逐渐减小的趋势,而随着围压的增大,损伤模量呈先减小后保持动态稳定的趋势。损伤变量的计算充分考虑到围压的影响,可进一步增进对岩石损伤的认识。

Analysis of Damage Modulus of Rock

Rock is a typical brittle non-uniform material that is rich in various internal defects (cracks, pores, joints fissures), which make the rock damage and failure mechanism very complex. Theoretical and laboratory experimental studies indicate that energy plays an important role during rock deformation and failure and abrupt energy release causes rock failure. Under certain conditions, this energy release can constitute an energy dissipation catastrophe. From the thermodynamics perspective, the process of rock damage is irreversible and energy release, the essential characteristic of rock deformation and failure, reflects the process of the propagation of internal defects and decreasing strength. The process of rock damage is one of constant energy evolution, so rock deformation and fracture can be well described from the energy viewpoint. Based on previous studies of rock damage, we know that the elastic modulus decreases while plastic strain emerges in the loading process. Based on the above analyses, we can define the damage variable with respect to energy. By relating the effective and total stress in the unloading stage of the stress-stain curve, we can determine a method for calculating the damage modulus. We conducted a statistical analysis of the damage parameters of rock under uniaxial and triaxial states to calculate and contrast the damage moduli. The results show the damage modulus to have a gradual decreasing trend with increasing confining pressure, whereby the damage modulus first decreases and then tends to stabilize. In addition, our method for calculating the damage modulus takes full account of the influence of the confining pressure. Building on the studies mentioned above, the analysis results of this paper promote further understanding of rock damage and failure.