基于孔穴扩张理论的黏性土不排水剪强度计算

确定黏性土不排水抗剪强度(c_u)的常规测试方法存在着取样扰动或测试深度不足等缺陷,提出了基于孔穴扩张理论的黏性土不排水抗剪强度的测试方法,并应用于花岗岩残积黏性土、辉绿岩残积黏性土和花岗岩残积砂质黏性土的旁压试验和静力触探试验成果解释中,将两种试验得到的c_u值进行对比。结果表明:旁压理论的假设条件导致旁压试验得到的c_u值较静力触探试验得到的c_u值大,其中等容剪切法计算过程对初始扰动和应变数据的选择非常敏感,导致计算结果差异较大;直接传统法能够克服初始扰动,c_u值受临塑压力的影响较小,计算结果与土体性质以及试验点深度较吻合,其c_u值约为静力触探试验的1.2倍,是一种简单、有效的确定黏性土不排水抗剪强度的方法。

Calculation of undrained shear strength of clayey soils based on cavity expansion theory

There are defects such as sampling disturbances and inadequate test depth in conventional test methods of determining undrained shear strength of clayey soils, so test method based on cavity expansion theory were suggested and applied to result interpretation of pressure meter test and cone penetration test for granite residual clayey soils, diabase residual clayey soil and granite residual sandy clay, and the cu values derived from these two tests were compared. The results show that the assumptions of pressuremeter theory resulted in higher cu values compared with that derived from cone penetration test. In particular, The calculation process of iso-volumetric shear method is sensitive to drilling disturbances and strain value, so the results obtained from this method are easily fluctuated; while cu values obtained by direct traditional method, usually 1.2 times of cone penetration test value, are in agreement with the soil properties and depth of testing points because its sensitivity to initial disturbances is less, demonstrating that direct traditional method is a simple and effective method in determination of undrained shear strength of clayey soils. 