基于室内试验与数值模拟的膨胀土裂隙对强度影响规律研究

Law of strength under influence of expansive soil cracks based on the laboratory test and numerical simulation

针对室内试验测试多裂隙发育膨胀土抗剪强度指标的困难,提出以室内试验与数值模拟相结合的研究方法;以不同产状单裂隙面膨胀土三轴试样在200kPa围压下的CD试验结果为样本,基于颗粒流原理,采用PFC3D软件进行仿真试验,获得了与三轴试验结果相一致的PFC3D球颗粒参数和裂隙参数;以此参数为基础,进行不同裂隙产状膨胀土的仿真试验,初步探寻了裂隙发育对广西宁明膨胀土的强度影响规律。研究发现:裂隙发育是膨胀土强度衰减的主要原因;裂隙的空间角度、不同裂隙的组合、裂隙发育程度均对膨胀土抗剪强度指标产生影响,且对黏聚力的影响较大;与无裂隙情况相比,裂隙率达14.06%时,C值降低71.2%。

the law of strength under influence of development of fracture has always been one of the research focuses and difficulties. According to the difficulty of testing the strength of expansive soil with developing fissures, taking the CD test results in ambient pressure of 200kPa of expansive soil with different single fractured as samples, on the basis of the principle of particle flow, with PFC3D software the particles microscopic parameters can be obtained by PFC3D simulation tests, and based on the parameters, simulation tests are carried on the of expansive soil with different crack attitudes. The law that fracture development influences on the strength of Ningming expansive soil is preliminarily explored. Research shows that the space angle of cracks, combination of different cracks and fissure rate influence the strength index, and greatly influence cohesive force. Development of cracks is the main reasons of the expansive soil strength degradation. For instance, when the fracture rate is 14.06% the C value reduces to 70.9%.