Experimental Study On The Mechanical Characteristics Of Lightweight Soil In Highway Widening Application In Mountainous Area

Foamed lightweight soil is a new type of subgrade filling material,which has many advantages,such as high strength,light weight,self-setting,convenient construction and so on.According to the mechanical properties of the light soil subgrade,and based on mechanical experiment,model experiment and simulation combined analysis method.This paper study the basic mechanical properties,deformation characteristics and damage mechanism in lightweight soil subgrade in the process of load-failure.The variation law of the strength of the foamed light soil after adding the raw soil(silty sand),the three axis mechanical properties of the light soil,and the variation of strain,stress distribution and the law of deformation in the process are obtained.The paper provides some theoretical and reference basis for the design and construction of the light soil subgrade.The main research results are as follows:(1)The compressive strength of foamed mixture lightweight soil linear decrease with the increase of raw soil,when raw soil contents more than 32%,it effects much and the porosity increased clearly.(2)In the process of three axial compression,the lightweight soil has obvious brittle failure characteristics,which is different from other filling material for subgrade.but under the condition of large confining pressure,the stress-strain relation of the lightweight soil is close to that of the soft soil.(3)In the process of load-failure of the lightweight soil subgrade,when the load reaches 175 kPa,plastic deformation firstly occur to the middle subgrade in the left side until the damage.With the increase of load,the junction between lightweight soil subgrade and old subgrade is affected by the interaction of the settlement deformation of old subgrade and the failure deformation of new subgrade to having bending shear failure crack,resulting in subgrade instability.The foamed lightweight soil subgrade load-failure mode is from inside to outside with elastic deformation to plastic yield,finally to shear failure,it is local damage to overall instability.