Dynamic Behavior of Clay-Aggregate Mixtures

Kang Fei,Jinxin Xu

doi:10.1155/2017/2479507

Abstract

Clay-aggregate mixtures are frequently used in engineering practice. To improve the understanding of the effects of coarse particles on the dynamic behavior of clay-aggregate mixtures, series of stress controlled cyclic triaxial tests were performed on clay specimens with various glass bead contents. The results show that the initial shear modulus of clay-aggregate mixtures increased with the increase of the coarse aggregate content and the confining stress. At the confining stress of 100, 200, and 400 kPa, the addition of 32% coarse particles caused an increase in the initial shear modulus of 117%, 110%, and 67%, respectively. Moreover, the normalized shear modulus decreased and damping ratio increased with the coarse aggregate content, and the influence of the confining stress on the strain-dependent dynamic properties was negligible. The specimen with a higher coarse aggregate content was observed to have larger cyclic shear strength and smaller excess pore water pressure, but the effects of the coarse aggregate content became less pronounced under large cyclic stresses.

Highlights

Clay-aggregate mixtures refer to clays mixed with sand, gravel, or cobble particles
At large cyclic shear stress (CSR = 0.25), the soil skeleton consisting of clay and coarse particles was susceptible to collapse after a few loading cycles; the pore water pressure generation was dominated by the clay fraction
To improve the understanding of the dynamic behavior of clay-aggregate mixtures, series of stress controlled cyclic triaxial tests were performed on clay specimens mixed with different amounts of coarse particles

Summary

Introduction

Clay-aggregate mixtures refer to clays mixed with sand, gravel, or cobble particles. These types of composite soils are frequently used in engineering practice. Studies of the dynamic behavior of soil mixtures have concentrated mostly on the effects of clay content on the cyclic shear strength of clay-sand mixtures. A different pattern in dynamic properties with the coarse aggregate content was observed by Meidani et al [27] They concluded that the samples with higher gravel content have higher normalized shear modulus and lower damping ratio. To obtain a full understanding of the effects of the coarse particles on the dynamic characteristics of clay-aggregate mixtures, stress controlled cyclic triaxial tests were carried out in this study. On the basis of the test results, the effects of the coarse aggregate content on the strain-dependent shear modulus, the damping ratio, the dynamic pore water pressure, and the cyclic strength were analyzed

Experimental Program

Test Results

Conclusions