配合比对三合土抗剪强度影响的试验研究

Influence of Mix Ratio on Shear Strength of Tabia

按2因素3水平完全试验设计方法拟定了9组三合土配合比,然后进行各试验组的击实试验,根据每组最大干密度和相应最优含水率进行了直剪强度试块制作并分别标准条件养护7天和28天进行抗剪强度试验,得到了各个试验组的抗剪强度指标黏聚力和内摩擦角。通过极差分析和趋势分析,得出结论:7天和28天龄期三合土的砂对内摩擦角的影响均大于黏土的影响;7天龄期砂对黏聚力的影响大于黏土的影响,28天龄期砂对黏聚力的影响小于黏土的影响;三合土内摩擦角最大的配合质量比为石灰:黏土:砂=1:4:5;黏聚力最大的配合质量比为石灰:黏土:砂=1:6:3;对7天养护龄期的情况,以竖向压力196 kPa为大小分界,可分别得到抗剪强度较大的两种配合比。研究成果可为工程应用中合理选择三合土配合比提供参考。

Nine groups of mix proportions of tabia are proposed by complete test design method with 2 factors and 3 lev-els,and compaction test of each group is carried out.Shear strength test blocks are made according to the maximum dry density and the corresponding optimum moisture content of each group,and maintained on standard conditions for 7 days and 28 days respectively for shear strength test.The shear strength index of cohesion and internal friction angle of each test group are ob-tained.The following conclusions are obtained through range analysis and trend analysis.The influence of sand in tabia with 7 days and 28 days on the internal friction angle is greater than the influence of clay;the influence of sand with 7 days on cohesion is greater than that of clay,while influence of sand with 28 days on cohesion is less than that of clay.The mix ratio of tabia that reached maximum internal friction angle is lime:clay:sand=1:4:5,and the mix ratio of tabia that reached maximum cohesion is lime:clay:sand=1:6:3.For 7 days,taking the vertical pressure of 196 kPa as critical value in magnitude,two kinds of mix proportions with maximum shear strength of tabia can be obtained respectively.The research results may provide reference for rational selection of mix proportion of tabia in engineering application.