珠三角地区典型淤泥质土硬化土本构模型参数研究

Study on constitutive model parameters of hardening soil for typical silt soil in the Pearl River Delta region

为了探讨硬化土本构模型对珠三角地区软土地下工程数值分析的适用性,基于4种不同应力路径三轴试验,分析了本地区典型淤泥质土力学性态及其硬化土本构模型参数的变化规律。研究表明,侧向卸荷及排水条件对淤泥质土硬化土本构模型强度参数c'、φ'值以及刚度参数E_(50)^(rd)、E_(ur)^(rd)和m影响显著,但对破坏比R_(f)的影响较小。对于固结不排水侧向卸荷条件,珠三角地区典型淤泥质土硬化土本构模型主要参数为:参考割线模量E_(50)^(ref)为2.34MPa,参考切线模量E_(oed)^(ref)为1.59MPa,参考加-卸载模量E_(ur)^(ref)为11.67MPa,破坏应力比R_(f)为0.98,刚度应力水平相关幂指数m为1.84;其中:E_(50)^(ref)约为E_(ord)^(ref)的1.47倍,E_(ur)^(ref)约为E_(ord)^(ref)的7.34倍。珠三角地区某软土深基坑工程实践证明,硬化土本构模型适用于模拟该地区软土力学性态。

In order to explore the applicability of the hardening soil constitutive model for numerical analysis of soft soil underground engineering in the Pearl River Delta region,and based on four different stress path triaxial tests,the mechanical properties and variation of constitutive model parameters of hardening soil were analyzed for the typical silty soil in this region.Research results have shown that lateral unloading and drainage conditions have significantly impact on the partial parameters of constitutive model,such as the strength parameters of e'andφ',the stiffness parameters such as E_(50)^(ref)、E_(ur)^(ref)and m,but the impact on the failure ratio R_(f)is relatively small.For the consolidated undrained lateral unloading condition,the main parameters of the constitutive model for typical sily soil in the Pearl River Delta region are shown as the reference secant modulus E3o is 2.34 MPa,with reference to tangent modulus E_(oed)^(ref),is 1.59 MPa,with reference to the loading unloading modulus E_(ur)^(ref)is 11.67 MPa,with a failure stress ratio of R_(f)is 0.98,and the power exponent m related to siffifess stress level is 1.84;Among them:E_(50)^(ref)is 1.47 timesof E_(oed)^(ref),E_(ur)^(ref)is 7.34 times of E_(oed)^(ref).The praetice of a deep foundation pit of soft soil in the Pearl River Delta has proven that the constitutive model of hardening soil is suitable for simulating the mechanical properties of soft soil in this region.