既有铁路路基挤密桩加固中水泥改良土特性试验研究

Experimental Study on Characteristics of Cement-improved Soil in Reinforcement of Compaction Piles for Existing Railway Sugrade

对宁启铁路中某段现场的粉质黏土进行室内试验,采用的水泥掺入比分别为4%,7%,10%,13%。对水泥改良土样进行分组击实、养护及无侧限抗压强度试验,获得了不同水泥掺入比改良土的击实特性及力学特性。试验结果表明:水泥掺入比对改良土的最优含水率及最大干密度影响不大,可依据原路基粉质黏土填料的压实标准作为控制水泥改良粉质黏土的压实标准。水泥改良粉质黏土的最优水泥掺入比是10%,7天的养护期即可满足现场施工挤密桩加固不低于1 MPa的要求。

The laboratory test was carried out on the silty clay in certain section of Nanjing-Qidong Railway with the cement content being 4 %, 7 %, 10 % and 13 % respectively; then the compaction, maintenance and unconfined compressive strength tests in groups on the specimen of cement-improved soil to get the compaction and mechanical properties thereof. The test results show that the cement content has minor effect on the optimal water content and max. dry density of such improved soil, the compaction standard of cement- improved silty clay may accord with that of original subgrade filler of silty clay. The best cement content for cement improved silty clay is 10 %, and 7-day maintenance gives the strength not less than 1 MPa, which can meet the requirement of reinforcement of compaction piles in the site construction.