卸荷应力路径下海积软土力学性质试验

摘要

利用GCTS空心圆柱扭剪仪对天津滨海新区第一海相沉积软土进行了卸荷应力路径下的三轴试验，探讨等P、减P应力路径下土样的应力-应变、孔隙水压力、有效应力路径、应变速率等特性。试验结果表明：不同应力路径下土样的力学性质有很大的不同，减P土样最终破坏时的应变量要比等P土样的小很多；不同应力路径下土的峰值强度不同；试样的孔隙水压力经历了先增加后减小的过程，当孔压达到峰值时，土样的抗剪强度最小，也是基坑开挖最危险的时刻。其研究成果可为解决软土地区的基坑开挖、隧道施工等卸荷工程问题提供理论支持。%Triaxial tests under unloading stress path were conducted in first marine sedimentary soft soil of Tianjin Binhai new area by using GCTS hollow cylinder torsional shear apparatus, exploring the tress-strain, pore water pressure, effective stress path, strain rate of soil under two kinds of stress paths:DG (constant P) and DE (reduce P).The experimental results pointed that mechanical properties of soil under different stress paths were quite different. The deformation of DE (reduce P) soil samples are much smaller than the DG (constant P)soil samples, when the soil sample is eventually destroyed. The peak strength under different stress paths is not the different. The pore water pressure of the sample in creases firstly and then de-creases. When the pore pressure reaches the peak, the shear strength of soil samples is minimal, which is also the most dan-gerous moment of excavation. Research results give theoretical support to excavation, tunneling and other geotechnical en-gineering problems in the soft soil area.