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在自然环境中,干缩裂缝是导致土质堤坝、土坡及黏土衬垫等产生渐进破坏的重要因素之一,亟待发展有效的定量研究手段来揭示黏性土干缩裂缝演化的力学机制。为此,基于已有的黏性土干缩机理建立了离散元模型,模型中颗粒半径、颗粒胶结接触参数均随含水率的变化而变化;进而采用PFC3D软件模拟了圆形薄层黏性土试样在粗糙边界条件下干缩裂缝的产生及扩展过程,采用图像技术定量分析了表面裂缝的几何参数,并与室内试验结果进行了对比分析。结果表明,模拟的开裂机制反映了拉应力和内部缺陷的共同作用;模拟的裂缝扩展过程表现出三阶段特征,表面裂缝参数的演化规律与室内试验结果基本一致;边界黏结强度对裂缝形态的影响规律与前人成果吻合。
In natural environment, shrinkage cracking is one of the most important factors that lead to gradual destruction of soil dams, soil slopes and clay linings. It is urgent to develop effective quantitative research methods to reveal the mechanical mechanism of the evolution of shrinkage cracks in clay soil. For this reason, a discrete element model was established based on the existing shrinkage mechanism of cohesive soil. The particle radius and particle-cementing contact parameters in the model all changed with the change of water content. Then the PFC3D software was used to simulate the effect of circular thin cohesive soil The generation and propagation of dry shrinkage cracks under rough boundary conditions were analyzed by using image technique. The geometrical parameters of surface cracks were quantitatively analyzed and compared with the indoor experimental results. The results show that the simulated cracking mechanism reflects the combined effect of tensile stress and internal defects. The simulated crack propagation process shows three-stage characteristics. The evolution law of surface crack parameters is basically the same as the indoor test results. The influence of the boundary bond strength on the fracture morphology Law consistent with previous achievements.