弱化后粗粒岩土力学特性及其对边坡稳定性的影响研究
Study on Mechanical Properties of Coarse Grained Rock and Soil After Weakening and Its Effect on Slope Stability
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摘要: 为探清某露天露天矿边坡长期积水后岩土体抗剪指标弱化情况,分别对砂砾土、泥岩及两者混合样采取了固结不排水剪法进行了松散土岩大三轴剪切试验。试验结果显示:砂砾土剪切强度和内摩擦角由38 kPa和23.2°降低为7.4 kPa和18.8°;泥岩的抗剪强度和内摩擦角由136 kPa和27.3°降低为7.8 kPa和20.7°。采用滑坡反分析验证了试验结果的可靠性,并对现状边坡进行了稳定性计算;结果表明,边坡长期受水浸泡及风化影响,其抗剪强度弱化明显,不利于边坡的安全,该结果可为边坡稳定评价及参数优化提供科学依据。Abstract: To investigate the weakening situation of shear resistance index of rock and soil mass after long-term water accumulation in the slope of an open-pit mine, large triaxial shear tests of loose soil and rock are carried out by the consolidated undrained shear method for gravel soil, mudstone and their mixture. The results show that the shear strength and internal friction angle of sand-gravel soil decreases from 38 kPa and 23.2° to 7.4 kPa and 18.8°, respectively; meanwhile, the shear strength and internal friction angle of mudstone decreases from 136 kPa and 27.3° to 7.8 kPa and 20.7°, respectively. The reliability of the test results is verified by back analysis of landslide, and the stability of the existing slope is calculated. The results show that the shear strength of the slope is obviously weakened due to long-term water immersion and weathering, which is not conducive to the safety of the slope. The results can provide a scientific basis for the slope stability evaluation and parameter optimization.
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