高速公路改扩建膨胀土路堤处置方法研究

Study on Treatment Method of Expansive Soil Embankment in Expressway Reconstruction and Extension

为在高速公路改扩建工程中充分利用膨胀土填料,该文借鉴膨胀土直接筑路的成功经验,依托G40沪陕高速公路合肥至大顾店段改扩建项目,提出采用土工格栅加筋膨胀土包边的路基处置方案。通过室内试验开展膨胀土填料的路用特性和膨胀性试验,确定填料的适用范围和压实控制指标。最后,通过路堤湿胀量预估、土工格栅加筋边坡稳定性分析和经济效应分析,对处置方案的可行性进行论证。结果表明:填料胀缩总率为1.12%,R_(CBR)大于3%,初步验证了该膨胀土样可采取包边、加筋等物理处置后用作下路堤填料的可行性。若采用湿法击实试验所确定的压实控制指标,路堤湿胀量预估值将比干法的小1个数量级。各层土工格栅的抗拔安全系数均满足规范不小于2.0的要求,不会存在拔出风险。相比石灰改良方案,该方案可极大地缩短工期和节约造价。

In order to fully utilize expansive soil as filler in highway reconstruction and expansion projects,this paper draws on the successful experience of using expansive soil directly in road construction.It proposes an embankment treatment scheme that involves the use of geogrid-reinforced expansive soil with edge wrapping,based on the reconstruction and expansion project of the Hefei to Dagudian section of the G40 Shanghai-Shaanxi Expressway.Through laboratory tests,the road performance and swelling characteristics of the expansive soil filler were investigated to determine the applicable scope and compaction control indices of the filler.Then,the feasibility of the embankment treatment scheme was demonstrated through the prediction of the embankment swelling,stability analysis of geogrid-reinforced slopes,and economic effect analysis.The results show that the total swelling-shrinkage ratio of the filler is 1.12%,and its R_(CBR) is greater than 3%,preliminarily verifying the feasibility of using physically treated expansive soil filler,such as edge wrapping and reinforcement,as lower embankment material.If the compaction control index determined by the wet compaction test is used,the estimated value of the embankment swelling will be an order of magnitude smaller than that determined by the dry compaction method.The anti-pullout safety factors of the geogrids at each layer meet the standard requirements of not less than 2.0,avoiding the risk of pullout.Compared to the lime improvement scheme,this scheme can significantly shorten the construction period and reduce costs.