侧向卸荷条件下结构性软黏土典型力学特性

为研究海积结构性软黏土在侧向卸荷路径下的结构损伤特性,通过温州瑞安软黏土侧向卸荷条件下的应力路径试验,研究侧向卸荷路径和结构性对软黏土应力-应变关系、强度、初始卸荷模量等典型力学特性的影响;分析应力路径和土样深度对初始结构性及损伤特性的影响.试验结果表明:温州软黏土应力-应变关系呈明显应变软化型,具有较强的结构性;侧向卸荷条件下,初始切线模量与平均固结压力呈线性关系,斜率为加荷条件的1.4倍;侧向卸荷条件下达到峰值强度时对应的应变较常规加荷条件小.拓展了应力比结构性参数的应用范围,计算结果表明侧向卸荷条件下初始应力比结构性参数明显大于常规加荷条件.结构损伤曲线可分为平稳损伤、加速损伤和减速损伤三段,常规加荷条件下加速损伤段的损伤速率明显大于卸荷条件,这种差异与其各向异性有关,施工时需予以重点关注.

Typical mechanical characteristics of structural soft clay under lateral unloading condition

To study the structural damage characteristics of marine soft clay under lateral unloading path,stress path tests under lateral unloading condition on the clay obtained from Ruian, Wenzhou were carried out to study the influence of lateral unloading path and structure on stress-strain relationship, shear strength, initial tangent modulus, and other typical mechanical properties. The influences of stress path and soil depth on initial structure and characteristics of structural damage were analyzed. The experimental results show that the structure of Wenzhou soft clay is strong and its stress-strain relation is obviously strain-softening. Under lateral unloading condition, the initial tangent modulus is linearly related to the average consolidation pressure, and the slope is 1.4 times that of the loading condition. The corresponding strain at peak strength of shear stress is smaller than that under loading conditions. The stress ratio structural parameters of soft clay under lateral unloading condition were presented.The results show initial stress ratio structural parameters under lateral unloading condition is obviously larger than those under loading condition. The structural damage curves can be divided into three sections: smooth damage, accelerated damage and deceleration damage.The structural damage rate under loading condition in accelerated damage section is faster than that under lateral unloading condition. The difference of structural damage rate which needs more attentionis related to the anisotropy of soft clay.