淤泥再生混合轻质土强度特性试验研究

Experimental study on strength properties of mixed lightweight soil from recycled sludge

为揭示混合轻质土的强度特性,该文对以工程废弃淤泥为原料土、发泡聚苯乙烯(EPS)颗粒为轻质材料配制并固化而成的淤泥再生混合轻质土的强度特性与强度机理进行了试验研究。通过不固结不排水三轴试验和直剪试验分析了EPS颗粒体积分数、围压、养护龄期及水泥掺入比等因素对其强度特性的影响。结果表明:不同EPS颗粒体积分数和水泥掺入比下混合轻质土试样的p-q曲线呈线性关系,q=mp+α。EPS颗粒体积分数越大,α值越小,水泥掺入比越大,α值越大,两参数均对m值影响较小。在一定应力范围内,混合轻质土的抗剪强度包络线是一条直线,其抗剪强度与水泥掺入比、EPS颗粒体积分数、围压、龄期等均有关系。试样的抗剪强度随着围压的增大而增大。粘聚力随水泥掺入比的增大而增大,随EPS颗粒体积分数的增大而减小。养护龄期越长,混合轻质土的强度和粘聚力越高。混合轻质土的强度发展机理与一般粘性土类似,其强度为粘聚分量、剪胀分量和摩擦分量之和。

In order to reveal the strength properties of mixed lightweight soil,the strength properties and mechanism of mixed lightweight soil from recycled sludge are investigated experimentally,which is prepared and solidified with the engineering waste sludge as raw soil and expanded polystyrene(EPS) beads as light materials.The effects of the cement content,volume fraction,confining pressure and curing age,etc of EPS beads on their strength properties are analyzed by unconsolidated undrained triaxial test and direct shear test.The results show that the p-q curves of mixed lightweight soil are linear for different EPS beads volume fraction and cement contents,q=mp+α.The larger the EPS beads volume fraction is,the smaller the value of α is,but the value of m changes a little.The larger the cement content is,the larger the value of α is,but the value of m changes a little.At a certain stress range,the shear strength envelope curve of mixed lightweight soil is a straight line,and the shear strength is connected with the cement content,EPS beads volume fraction,confining pressure and curing age,etc.The shear strength of the samples increases with the increase of confining pressure.The cohesive force increases with the increase of cement content and decreases with the increase of EPS beads volume fraction.The longer the curing age is,the higher the strength and cohesive force of the mixed lightweight soil are.The strength development mechanism of mixed lightweight soil is similar with that of ordinary soil,and its strength can be divided into cohesive component,dilatation component and friction component.