裂隙岩体几何与力学尺寸效应的关联性研究

Correlation of the geometrical and mechanical size effects of fractured rock masses

利用块体化程度指标,从岩体空间结构角度,揭示岩体几何与力学尺寸效应的关联性。基于GeneralBlock软件构建35种不同结构面延展性和间距组合的岩体多尺度三维裂隙网络模型,利用所提出的块体化程度修正理论,计算不同尺度岩体的块体化程度,确定裂隙岩体的几何特征尺寸(即几何REV);通过GeneralBlock–3DEC模型关联参数的对接,构建多尺度岩体离散裂隙网络模型,分析岩体抗压强度、弹性模量等特征力学参数随岩体尺寸的变化规律,计算裂隙岩体的力学特征尺寸(即力学REV);比较几何REV与力学REV的计算结果,探讨岩体几何尺寸效应与力学尺寸效应的关联性。研究表明:岩体几何REV尺寸小于岩体力学REV尺寸,且岩体力学尺寸效应主要由岩体几何尺寸效应引起;随着岩体尺度的增加,反映岩体结构特性的几何特征参数先趋于稳定(即先期达到几何REV),达到力学REV后岩体的力学特征参数趋于稳定。

Based on the blockiness index,this study attempts to unravel the correlation of the geometrical and mechanical size effects of fractured rock masses from the perspective of the spatial structures of rock masses.First of all,a total of 35 types of multi-scale three-dimensional fracture networks of rock masses,possessing various combinations of different persistence and spacing of discontinuities,were established by GeneralBlock.Using the improved blockiness evaluation method developed by the authors,the blockiness values of the rock masses with different scales were measured,and the geometrical representative element volumes of rock masses(i.e.,geometrical REV)were obtained.Then,multi-scale discrete fractures networks of rock masses were built by the combined use of GeneralBlock and 3 DEC,the change law of the rock mass compressive strength and elasticity modulus with rock mass sizes was discussed,and the mechanical representative element volumes(i.e.,mechanical REV)were determined.Finally,the geometrical and mechanical REVs were compared,and then the correlation of the geometrical and mechanical size effects of fractured rock masses was evaluated.The results show that the geometrical REV is lesser than the mechanical REV,and the mechanical size effect is induced by the geometrical size effect;with the increase in the scales of rock masses,the geometrical parameters tend to be stable,and then the mechanical parameters are the same(i.e.,the geometrical REV is achieved earlier than the mechanical REV).