重复压缩-回弹条件下土石混填体变形规律与压实指标相关性试验研究

Experimental study for soil-rock mixture about deformation law and correlation between compaction indexes under repeated compression-rebound

从湖南省龙(山)—永(顺)高速公路大坝隧道弃碴填筑体取样,开展土石混填体压实模拟及压实评价指标室内对比试验。研究结果表明:土石混填体压缩曲线呈上凸型;回弹曲线平缓圆滑,呈微下凹型;第i+1次压缩回弹曲线均位于第i次曲线下方,线形相似;土石混填体变形具有记忆效应;湿化对土石(灰岩)混填体压实变形特征影响不明显;分级加载比1次加载产生的变形大;随着循环荷载和加载次数增加,累积总变形、累积塑性变形和累积塑性变形率增大,压缩5次基本不再增大;分级总变形、分级塑性变形和分级塑性变形率随加载次数增加而减小,减小率也不断减小;当循环荷载超过400 kPa时,分级总变形、分级塑性变形和分级塑性变形率基本接近;在工地碾压过程中,采用高吨位压路机或者轻重机具组合碾压5次,能有效提高土石混填体的压实度;压实评价指标K30(地基系数)、Ev1(静态变形模量)与e(孔隙比)具有较好的相关性,Ev2(静态变形模量)、Evd(动态变形模量)与e(孔隙比)的相关性较差;K30和Ev1可作为土石混填体压实质量评价指标。

Samples were obtained from the Daba tunnel of the Longyong highway in Hunan Province,and compaction simulating and comparative test of compaction quality indexes were carried out.The results show that the compression curves of soil rock mixture are overall convex type in plate loading test,and the rebound curves are smooth and slightly concave type.The(i+1)th compression-rebound curve is located below the ith curve,and has the similar linearity.The over-pressure curve has memory effect.The effect on wetting compaction deformation characteristics of soil-rock(limestone)mixture is not obvious.The deformation caused by the step loading is larger than that of the single loading.All of the cumulative total deformation and cumulative plastic deformation and ratio of accumulative plastic deformation increase with the increase of cyclic loading and loading times,but do not increase when cyclic times exceed5times.The classification total and plastic deformation and ratio of classified plastic deformation decrease with the increase of loading times,and the decreasing rate also decreases.But when cyclic loading exceeds400kPa,the classification total deformation and plastic deformation and ratio of classified plastic deformation are approximately equal.In the site rolling process,the use of high tonnage roller and5times combination rolling of light and weight equipment can effectively improve the compaction degree of soil rock mixture.Void ratio e has good correlation with compaction quality index K30(foundation coefficient)and Ev1(static deformation modulus),but little correlation with compaction quality index Evd(dynamic deformation module)and Ev2(static deformation modulus).K30and Ev1may be effective in evaluating indicators of compaction quality for soil-rock mixture.