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土体抗剪强度是边坡稳定性分析的重要力学参数,而大型直剪试验是确定粗粒土抗剪强度指标较为有效的方法,但获取所需原状土样较为困难。通过现场挖取边坡残坡积原状土样,开展原状土样和击实土样的室内常规小型直剪对比试验,证明在有效控制密度、干密度和含水率条件下采用击实土样获取的直剪强度指标可替代原状土样试验结果。击实土样的大型直剪与原状土样的常规直剪试验结果对比分析表明,由常规小型直剪试验获得残坡积土的抗剪强度略高于大型直剪试验结果。由于室内常规小型直剪试验获取的抗剪强度指标往往比边坡实际发生滑动时的抗剪强度指标稍大,建议在边坡稳定性分析中对抗剪强度指标选取时,采用以大型直剪试验获得的有效控制密度、干密度和含水率条件下击实土样的峰值强度和残余强度,由此进行的边坡稳定性计算将更为科学合理。
The shear strength of soils is an important mechanical parameter for slope stability analysis. However, the large-scale direct shear test is a more effective method to determine the shear strength index of coarse-grained soils, but it is difficult to obtain the required intact soil samples. Through on-site excavation of slope slope slope intact soil samples, to carry out the original soil samples and compacted soil indoor conventional small direct shear contrast test, to prove that the effective control of density, dry density and moisture content obtained by compaction soil samples The direct shear strength index can replace the original soil test results. Comparing and analyzing the results of conventional direct shear tests of the large scale direct shear specimens and the undisturbed soil specimens, it shows that the shear strength of the residual soil obtained by the conventional small scale direct shear test is slightly higher than that of the large scale direct shear test. Because the shear strength index obtained by conventional small-scale direct shear tests in the interior tends to be slightly larger than the shear strength index when the slope actually slides, it is suggested that when the shear strength index is selected in the slope stability analysis, It is more scientific and reasonable to calculate the peak strength and residual strength of soil samples under the conditions of effective control density, dry density and water cut.