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.