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浅层坍滑是膨胀土边坡在大气干湿循环作用下必然发生的地质灾害,常给膨胀土地区工程建设带来极大困扰。为探究特定边界条件下膨胀土的真实强度,文章开展了干湿循环含低应力条件下百色膨胀土常规饱和慢剪试验,对比分析了摩尔库伦直线、双直线、广义幂函数法拟合所得抗剪强度参数及低应力段三法拟合值与实测值的差异,得到随循环次数增加,三法拟合所得抗剪强度参数均呈大幅衰减,且衰减主要体现在粘聚力(或纵轴交点值)的大幅降低上,内摩擦角虽有减小,但降幅不大;低应力段抗剪强度实测值与摩尔库伦直线法拟合值差异大,而双直线、广义幂函数法差异小,表明低应力下膨胀土强度包线具有明显非线性特征,验证了已有研究成果的合理性。
Shallow collapse is the geological disasters of expansive soil slope inevitably occurring under the action of dry-air circulation in the atmosphere, which often brings great trouble to the engineering construction of expansive soil area. In order to explore the true strength of expansive soils under certain boundary conditions, the paper conducts a conventional saturated slow shear test of Baise expansive soils under wetting and wetting conditions with low stress. Comparing the results of Mohr-Coulomb linear and bilinear curves, Shear strength parameters and the low stress section of the three methods fitting the measured value and the measured value, get the number of cycles increases, the three law fitting the resulting shear strength parameters showed a sharp decline, and the attenuation is mainly reflected in the cohesion (or vertical axis But the decrease was not significant. The difference between the measured value of shear strength in low stress section and the fitted value of Moore Coulomb linear method was large. However, the difference between the two straight lines and generalized power function method was small , Which indicates that the envelope strength of expansive soil under low stress has obvious nonlinear characteristics, which verifies the rationality of the existing research results.