人工制备互层土的静三轴剪切力学特性研究

Experimental study on static triaxial shear behavior of artificially prepared interlayered soil

互层土是一种广泛分布的特殊土体,目前对其基本力学特性的认识仍不充分。采用人工制备的粉质黏土与粉砂互层土,通过固结不排水三轴试验对其基本力学特性进行研究,重点分析了层厚比对互层土不排水剪切应力-应变、孔压、抗剪强度及破坏形态的影响规律。研究表明,互层土的力学性质介于两单层土(正常固结粉质黏土与中密粉砂)的力学特性之间,但并非二者的某种简单组合,而是受粉质黏土层与粉砂层的层厚比影响;随着互层土中粉质黏土层厚的增加,其应力-应变曲线由软化型变为硬化型,孔压发展由负孔压转变为正孔压,应变局部化(剪切带)破坏模式受到抑制,粉质黏土层的控制作用逐渐增强。

The interlayered soil is a type of widely distributed special soil.Its mechanical behavior has not been fully understood so far.The soil samples of silty clay interlayered by silty sand are artificially prepared for experiments.The consolidated-undrained triaxial tests are carried out to study the basic mechanical behavior of the prepared interlayered soils.The effects of the layer thickness ratio on the stress-strain relationship,pore pressure responses,shear strength and sample failure modes are analyzed.The results show that the mechanical behavior of the interlayered soil falls in between the behavior of the two constituent layers of soil,i.e.,a normally consolidated silty clay and a medium dense sand,but it is not a simple combination of the two.Instead,the layer thickness ratio plays an important role.As the thickness ratio of silt clay increases in the interlayered soil,its stress-strain curve transits from the softening type to the hardening one,the pore pressure changes from negative to positive,and the shear band type localization is suppressed,implying an enhanced role of silty clay layer.