关键词: 粉土, 三轴试验, 应力应变, 体应变, 剪胀性

Abstract:

Silt soils have been encountered in most of the estuary of Qiantangjiang River. Drained and undrained triaxial tests have been made to study the dilatancy of the saturated silts. The test results show that one of the most significant properties of Qiantangjiang silts is their dilatant characteristics in shear. The amount of potential dilatancy is governed mainly by voids ratio and confining pressure. Conclusions from the consolidated-undrained(CU) tests are the undisturbed samples of the medium density tend to dilate during shear in the cell pressures range 600 kPa while the compacted samples of the small density tend to dilate under the cell pressure of less than 400 kPa during shear. Due to their dilatant nature, the undrained strength of many silts keeps increasing during shear, for this case there is no unique “undrained strength”. The compacted samples whose quality has been demonstrated in the consolidated-drained(CD) tests to be slightly dense tend to dilate under the cell pressure of less then 400 kPa during shear. The failure of Qiantangjiang silts usually goes through larger deformations. The stress-strain curve of drained tests can be divided into four stages. It is reasonable that the point where the strain can continue without further change of volume is chosen as a failure criterion to define the drained strength of silt.

Key words: silt, triaxial test, stress-strain, volumetric strain, dilatancy