《Journal of Geotechnical and Geoenvironmental Engineering》杂志刊登“滞水特性对低塑性土小应变剪切模量的影响”

 
作者：Ali Khosravi ; John S. McCartney
刊物：《Journal of Geotechnical and Geoenvironmental Engineering》，2012年11月，138卷第11期，1326–1333页
关键词：非饱和土；滞水特性；小应变剪切模量；本构模型
摘要：试验研究表明：当用基质吸力函数作图时，由于非饱和土的滞水特性使得小应变剪切模量（Gmax）在吸水情况下测量值远远大于排水情况。为充分了解这个问题，建立了一个半经验模型来说明应力状态和滞水特性对低塑性土体的Gmax的影响。与以前的Gmax经验关系不同的是该模型包含了弹塑性本构关系，弹塑性本构关系将平均有效应力的影响和硬化的影响耦合在一起，其中硬化是由体积的塑性变化或饱和度的变化引起的。 同时将有效应力定义为有效饱和度与基质吸力的乘积和净法向应力的总和，这样使得土水特征曲线参数能很容易地耦合到模型中。本研究采用了一个可测量滞水特性情况下压实粉土的Gmax的试验检验程序来建立数据对模型标准的确认方法。利用有吸力-饱和度控制的固定-自由式共振柱试验机测得不同平均净法向应力，并将其定义为Gmax的滞后趋势。本文提出的用于定义模型参数的方法包含了相关关系的使用，也包含了对饱和条件下或排水过程中土体Gmax的试验测量。结果表明：模型与试验所测的Gmax随吸力、饱和度、排水过程中的有效应力的变化趋势能够很好地吻合，并且在一定程度上可预测Gmax随着吸水过程的变化。

Impact of Hydraulic Hysteresis on the Small-Strain Shear Modulus of Low Plasticity Soils

Authors: Ali Khosravi ; John S. McCartney
Journal: Journal of Geotechnical and Geoenvironmental Engineering, Volume 138, Issue 11 (November 2012), 1326–1333
Key words: Unsaturated soils;Hydraulic hysteresis;Small-strain shear modulus; Constitutive model
Abstract: Experimental studies have observed that the small-strain shear modulus (Gmax) of unsaturated soils measured during hydraulic hysteresis has a greater magnitude during imbibition than during drainage when plotted as a function of matric suction. To capture this behavior, a semiempirical model was developed to interpret the impacts of the stress state and hydraulic hysteresis on Gmax of low plasticity soils. Different from previous empirical relationships for Gmax, this model incorporates elastoplastic constitutive relationships, which integrate the effects of mean effective stress and hardening because of either plastic changes in volume or changes in the degree of saturation. The effective stress is defined as the sum of the net normal stress and the product of the effective saturation and matric suction, facilitating integration of the soil-water retention curve parameters into the model. An experimental testing program involving measurement of Gmax of compacted silt during hydraulic hysteresis was used to develop data to validate a methodology for model calibration. Specifically, hysteretic trends in Gmax were defined for different mean net normal stress values using a fixed-free resonant column device with suction-saturation control. The proposed methodology to define the model parameters includes use of correlations from the literature, as well as experimental measurements of Gmax for soils in saturated conditions and during drainage. The model was found to fit the trends in experimental Gmax data with suction, degree of saturation, and effective stress during drainage, and provided adequate prediction of the Gmax data upon subsequent imbibition.

原文链接：http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000713
翻译：孙庆雷；审核：安鹏