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在基坑、隧道开挖等过程中,不同部位的土体会经历不同的应力路径,在不同的应力路径下,土体可能表现出截然不同的静力学特性。同时,在工程实际中,土体的工作应变经常处于小应变范围,而在小应变情况下,土体的静力特性表现出更强的非线性和应力路径依赖性。基于广泛分布于东部地区,并且表现出诸多不良工程特性的软黏土,进行一系列不排水和排水条件下的应力路径静力试验,以研究应力路径对饱和软黏土静力特性,尤其是小应变情况下割线模量的影响。试验结果表明,不管在不排水还是在排水条件下,应力路径都对饱和软黏土的静强度产生巨大的影响,表现为围压增加的加载应力路径增大了静强度,而围压减小的卸载应力路径降低了静强度。同时,应力路径对割线弹性模量产生了更大的影响,围压增加的加载应力路径降低了割线模量,而围压减小的卸载应力路径增大了割线模量。应力路径对割线模量的影响在小应变时表现的更加明显,而这种影响主要原因是应力路径方向改变造成的土体各向异性。
In the process of foundation pit and tunnel excavation, the soil in different parts will experience different stress paths. Under different stress paths, the soil may show quite different statics. At the same time, in engineering practice, the working strain of soil is often in the range of small strain, while in the case of small strain, the static characteristics of soil show stronger nonlinear and stress path dependence. Based on a series of undrained and drained hydrostatic tests of soft clay, which are widely distributed in the eastern part of China, and show many undesirable engineering features, the stress path is used to study the influence of stress paths on the static characteristics of saturated soft clay, especially the small strain Effect of secant modulus on case. The experimental results show that the stress path has a great influence on the static strength of saturated soft clay both in undrained and drained conditions. The results show that the loading stress path with increasing confining pressure increases the static strength and the confining pressure decreases Unloading the stress path reduces the static strength. At the same time, the stress path has a greater influence on secant elastic modulus. The loading stress path with increasing confining pressure decreases the secant modulus, while the unloading stress path with decreasing confining pressure increases the secant modulus. The influence of stress path on the secant modulus is more obvious at small strain, which is mainly due to the soil anisotropy caused by the change of stress path direction.