基于软硬石模板库的土石混合体细观损伤与力学特性分析

为了探究含软、硬两种岩性碎块石土石混合体的变形破坏过程与力学性质，发展了一种基于软硬石模板库的土石混合体建模方法。通过在PFC2D中建立符合原位结构特征的软硬石模板库，利用此模板库生成了不同含石量土石混合体颗粒流模型，对土石混合体进行了单轴压缩颗粒流模拟。结果表明：土石混合体破坏始于土-石接触面，土石介质分离大多因剪切破坏导致，加载前期微裂纹迅速增长，中、后期微裂纹增长速率减缓，但宏观变形渐趋显著；随着含石量的增加，土石混合体单轴抗压强度逐渐降低，块石的转动与侧向移动会加剧土石混合体的整体破坏；相同含石量下，随着软石比例的增加，单轴抗压强度呈下降趋势，试验后试样破裂率与单个软石颗粒的破裂程度均保持在较高水平，软石颗粒破裂是引起土石混合体单轴抗压强度降低的重要原因。

Analysis of mesoscopic damage and mechanical behaviors of soil-rock mixture based on template database of soft and hard rocks

To explore the failure process and mechanical properties of soil-rock mixture (SRM) which contains soft and hard rock blocks, a modeling method for SRM is proposed based on the template database of soft and hard rocks. In the particle flow code in two dimensions (PFC2D) the template database of soft and hard rocks is established, which conforms to in-situ structural characteristics. The particle flow models of SRM with different rock block proportions (RBP) are generated, and then a series of uniaxial compression tests is simulated by the particle flow code. The simulation results indicate that the failure of SRM initiates from the interface between rock block and soil, and the separation of soil-rock medium is mostly caused by shear failure. The microcrack grows rapidly at the earlier stage of loading, and the growth rate of microcracks slows down at the middle and later stages, while the macroscopic deformation gradually becomes significant. The uniaxial compressive strength of SRM decreases with the increase of RBP. The rotation and lateral movement of rock block can aggravate the integral destruction of SRM. At a certain RBP, the uniaxial compressive strength of SRM shows a decreasing tendency with the increase of soft rock block proportion. The rupture rate of specimen and the rupture degree of single soft rock granule are maintained at a high level after the test, and the rupture of soft rock granules is an important reason for the decline of SRM’s uniaxial compressive strength.