关键词: 储气砂土, 应力路径, 表观凝聚力, 抗剪强度, 基质吸力

Abstract:

In order to reveal the influences of stress path on the deformation behavior and strength characteristic of unsaturated sand, the four kinds of stress path experimental study of conventional triaxial compression (CTC), reduced triaxial compression (RTC), conventional triaxial extension (CTE) and reduced triaxial extension (RTE) on shallow gassy sand from the Hangzhou Bay is carried out by GDS unsaturated triaxial system. The results show that the stress-strain relationship of unsaturated sand in unloading stress paths of RTC and RTE appears strain softening, and the light strain softening and significant strain hardening deformation behaviors for loading stress paths of CTC and CTE relatively. The shear strength parameters of unsaturated sand are also different under the condition of unloading and loading stress paths, the effective cohesion value of the former is higher than the latter; and the internal friction angle is the opposite. However, the relationships between the apparent cohesion and the matric suction in various stress paths of unsaturated sand are effectively described by the power function , and the test parameters of a and b are different. Therefore, the shear strength formula can be used to express the strength characteristic of unsaturated sand reasonably.

Key words: shallow gassy sand, stress path, apparent cohesion, shear strength, matric suction