孔隙结构特征及其对岩石力学性能的影响

 以砂岩为研究对象，利用统计学原理和FLAC3D软件重构了三维孔隙模型。在三维孔隙模型的基础上，应用数值模型试验的方法，通过多组孔隙分布特征参数的巴西圆盘劈裂数值模拟试验，分析并探讨了孔隙结构参数(孔隙率、孔径分布和空间位置分布)对孔隙砂岩力学性能的影响。研究结果表明：孔隙率严重地影响着孔隙圆盘模型的破坏状态，孔隙率较小时圆盘以拉伸破坏为主，孔隙率增大时出现拉伸和剪切共同作用的破坏方式。随着孔隙率的增大，圆盘模型的抗拉强度呈指数递减的趋势；随着孔径分布控制参数的减小，圆盘劈裂破坏区域增大且更加分散。当孔隙率较小时孔径分布对抗拉强度有一定的影响；孔隙空间位置的改变对圆盘破坏的影响主要体现在裂纹产生的位置上，没有改变圆盘的破裂方式和裂纹的数目，对圆盘抗拉强度也没有太大的影响。研究结果揭示了孔隙岩石变形破坏的内在机制，为研究孔隙结构参数对岩石物理力学性能的影响提供一定的参考。

INFLUENCE OF POROUS STRUCTURE PROPERTIES ON MECHANICAL PERFORMANCES OF ROCK

Using principle of statistics and FLAC3D，the three-dimensional porous structural models of sandstone are reconstructed. On the basis of the 3D porous structural models，the influences of porous structure parameters(pore number，pore radii distribution and space position distribution) on mechanical performances of sandstone are explored through a number of Brazil disk split tests with different pore distribution characters parameters by means of numerical simulation. The results indicate that porosity affects the failure states of disk models greatly. When the porosity is smaller，the tensile failure is main failure mode. When the porosity is larger，the tensile failure and shear failure act together. With the increase of porosity，the tensile strength decreases with exponential distribution. The split failure region of disk model is larger with the smaller pore radii distribution parameters. The pore radii distribution has some influences on tensile strength of disk model with smaller porosity. The influence of pore space position distribution on disk model failure mode is mainly concentrated in the place of crack occurring. It does not change failure mode and crack number of disk model. The effect of pore space position on tensile strength of disk model can be ignored. The achieved results disclose the intrinsic mechanisms of deformation and failure of rock and supply references for studying the influence of porous structure parameters on physical-mechanical performances.