孔隙水压和应力路径对软土卸荷力学参数的影响

The Effect of Pore Water Pressure and Stress Path on Soft Soil Unloading Mechanical Characteristics

摘要: 不同卸荷比和孔隙水压作用下软土的卸荷力学特性是软土地下空间设计计算重点关注的科学问题之一。但目前软土地下空间设计时忽视了孔隙水压和卸荷比对软土力学特性的弱化作用。针对该问题，为模拟基坑开挖不同位置经受的卸荷应力路径，以全自动应力应变控制式三轴仪进行卸荷力学特性试验。试验发现，软土对卸荷应力路径非常敏感，且随着孔隙水压的增大软土卸荷强度明显降低。

Abstract: The primary objective of the important scientific difficulties in the design and calculation of soft soil underground space is the unloading mechanical characteristics of soft soil under varying unloading ratios and pore water pressures. However, the weakening effect of pore water pressure and unloading ratio on the mechanical properties of soft soil is ignored in the design of soft soil underground space. An unloading mechanical characteristic test was carried out using a completely automated stress-strain control triaxial instrument in order to replicate the unloading stress path encountered by various positions of foundation pit excavation. According to the test, soft soil is extremely sensitive to the unloading stress route, and its unloading strength clearly declines as pore water pressure increases.