地基土抗剪强度试验对比研究

采用不同种类的土、在不同密实状态下，系统研究了三轴与直剪两种试验方法得到的地基土强度参数的差别，三轴试验方法为不固结不排水试验，直剪试验类型为快剪。试验结果表明：对于砂性土，两种试验方法得到的结果很接近，直剪强度参数（内摩擦角）略大；但对于粘性土，两种试验结果差别很大，直剪得到的内摩擦角约为三轴指标的0．87倍，粘聚力约为三轴指标的3．47倍。根据本文研究结果，在实际工程中测定粘性地基土的强度参数时，不适宜采用直剪方法。

Comparative Research on Shear Strength Tests of Foundation Soil

A comprehensive research on shear strength tests of foundation soil is presented to obtain the effect on the shear strength indexes considering different categories of soil and different compaction status. The triaxial test is unsolidated and undrained, and the direct shear test is quick-shear. The tests show that for sandy soil, the results are very closed, the shear strength index （friction angles） obtained from direct shear test is slightly higher. For clay, there is a obvious difference between these two test methods. The friction angle from direct test is approximately 0.87 times of that from triaxial test, and the cohesive force is 3.47 times of that from triax- ial test. The direct shear test should not be recommended to obtain the shear strength indexes in engineering practice.