固化轻质土在干湿循环及大变形条件下力学特性研究

A study of the mechanical properties of curing light soil under the condition of drying-wetting circles and large deformation

为了研究在多变自然气候环境影响下新型土工材料——固化轻质土的力学特性,以自行研制的固化轻质土为研究对象,通过控制含水率变化模拟干湿循环作用,研究不同密度固化轻质土强度随干湿循环次数变化的规律。利用GCTS环剪仪对不同密度的固化轻质土分别进行单级剪切、多级剪切和预剪切3种不同形式的环剪试验,分析固化轻质土抗剪强度指标c,φ值以及残余强度在不同剪切方式下的变化规律。结果表明:在干湿循环作用下,固化轻质土的抗剪强度在剪切初期明显下降,随后趋于稳定,土体密度越大,龄期越长,衰减趋势越小。对固化轻质土孔隙率测试表明,土孔隙率随着干湿循环次数的增加呈现出先增大后趋于平缓的变化趋势,从内部机理上解释了强度的变化规律。在大变形条件下,多级剪切形式下土体残余抗剪强度最大,预剪切次之,单级剪切最小。同种剪切方式下固化轻质土的残余抗剪强度与密度和法向应力成正比。

In order to study the mechanical properties of a new geotechnical material curing light soil under the influence of changeable natural climate environment,the self-developed curing light soil is taken as the research object,and the change in the strength of the curing light soil of different densities with the number of drying and wetting cycles is simulated by controlling the change in moisture content.The curing light soil of different densities is carried on a single shear,pre-shear and multistage shear test by GCTS ring shear apparatus for researching the rule that the shearing mode changes along with c,φand the residual shear strength.The experimental results suggest that under the drying-wetting circles,the curing light soil shows the obvious trends of attenuation and the stability in drying-wetting circles.The greater the density of soil is,the greater the rends of attenuation increase.The porosity of the soil shows a increasing trend and is steady with the increasing drying-wetting cycles.This explains the change trend of strength from internal mechanism.Under the large deformation,multistage shear has the greatest effect on the residual shear strength,the pre-shear second,and the single shear the lowest.The residual shear strength of the curing light soil is proportional to the density and normal stress.