EPS粒径对轻量土抗剪强度的影响规律  

Influence law of EPS size on shear strength of light weight soil

作　　者：侯天顺[1,2] 徐光黎[2] 

机构地区：[1]西北农林科技大学水利与建筑工程学院,陕西杨凌712100 [2]中国地质大学生物地质与环境地质教育部重点实验室,湖北武汉430074

出　　处：《岩土工程学报》2011年第10期1634-1641,共8页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(40572152);生物地质与环境地质教育部重点实验室开放基金项目(BGEGF200814)

摘　　要：为了确定EPS粒径对轻量土抗剪强度的影响,通过直剪试验研究了水泥掺入比12%、20%,EPS颗粒体积比40%的3种EPS粒径混合土的抗剪强度特性。结果表明:轻量土的剪应力–剪切位移关系曲线有硬化、软化两种形态,取决于水泥掺入比、法向应力等因素。抗剪强度包线为折线型包线,与传统结构性土体包线形态一致。水泥掺入比与EPS颗粒体积比相同时,随着EPS粒径增大,轻量土密度不变,抗剪强度减小,单价降低,但强度衰减率远远低于单价降低率;剪切面上EPS发生剪缩与剪断,受水泥掺入比、EPS粒径的控制;黏聚力随EPS粒径增大而减小,内摩擦角没有显著变化规律。轻量土剪切破坏过程,可以划分为变形协调、逐渐破损、纯摩擦3个阶段。提出了固化土、EPS 3界面接触抗剪强度模型,从理论上证明了混合土强度随EPS粒径增大而衰减的规律。根据混合土的强度衰减率低于单价降低率,推荐实际生产过程中可以采用3～5 mm的EPS球粒,进行配方寻优,适当降低造价。To determine influence of EPS （Expanded polystyrene） size on shear strength of light weight soil, the shear strength characteristics of mixed soil （cement mixed ratio of 12% and 20% and EPS volume ratio of 40%） with three kinds of EPS sizes are studied by means of direct shear tests. The results show that there are two types of shear stress-shear displacement relation curves： strain hardening and strain softening, and they are decided by cement mixed ratio, normal stress and so on. Its shear strength envelope is broken line, and it has the same shape as that of traditional structural soil. When the cement mixed ratio and EPS volume ratio are the same, with the increase of the EPS size, the wet density of light weight soil is constant, the shear strength decreases, the unit price reduces, but the strength reduction rate is far below the reduction rate of the unit price. Shear contraction or shear fracture may occur in EPS on shear planes, and it is decided by the cement mixed ratio and EPS size, Cohesion decreases with the increase of the EPS size, and internal friction angle has no obvious variation law. Shear failure processes of light weight soil can be divided into three stages： deformation coordination, progressive damage and pure friction. A shear strength model for 3 interfaces （stabilized soil-stabilized soil, stabilized soil-EPS, EPS-EPS） is brought forward. The strength reduction law of light weight soil with the increase of the EPS size is theoretically proved. According to the fact that the strength reduction rate is far below the reduction rate of unit price, EPS beads whose diameter is 3-5 mm should be used in construction, and prescription can be optimized, then the cost can be reduced appropriately.

关 键 词：轻量土 抗剪强度 EPS 粒径 直剪试验 

分 类 号：TU411.3[建筑科学—岩土工程]