岩样变形特性的二元介质模拟

围压低时岩石材料表现为应变软化。应变软化的合理描述对岩石工程非常重要。在岩土破损力学的理论框架内，认为加载过程中胶结元逐渐破损转化为摩擦元，二者共同抵抗外部荷载作用，胶结元（胶结块）在破损以前的应力应变特性可以用理想的弹脆性材料描述，胶结元破损后转化成的摩擦元（软弱带）的应力应变特性可以用硬化型弹塑性模型来描述。通过引入反映破损过程的破损参数（破损率和应变集中系数），建议了一个岩石材料的二元介质模型。最后与砂岩岩样的三轴试验结果进行了对比，表明所建议的模型具有较好的适用性。

Modeling the deformation properties of rock samples by Binary Medium Model

Rock materials exhibits strain softening at low confining pressure. How to accurately describe the strain softening is very important for rock engineering. A new model, referred to as Binary Medium Model for rock matrials, is formulated under the theoretical framework of breakage mechanics for geomaterials. In the model, rock materials is conceptualized as binary medium consisting of bonded blocks and weakened bands which are idealized as bonded elements and frictional elements respectively. During the loading process the bonded elements gradually fracture and transform to be the frictional elements. The deformation properties of the bonded elements are described by ideal elastic-brittle materials and those of the frictional elements are described by hardening elasto-plastic model. Two sets of breakage parameters, i.e., breakage ratios and strain concentration coefficients, describing the influence of rock structure on the process of failure are introduced. The proposed model has been used to predict the behavior of sandstone sample in triaxial compression test. By making comparisons of predictions with experimental data it is demonstrated that the new model provides satisfactory modeling of many important features of the behavior of rock materials.