干密度对土工格栅与膨胀土界面拉拔性状的影响

Effect of dry density on pull-out behaviors of interface between geogrids and compacted expansive soils

采用高密度聚乙烯(HDPE)单向土工格栅与聚脂(PET)双向土工格栅,以及南水北调中线工程新乡段的膨胀性泥灰岩风化土,在填土尺寸为600 mm×600 mm×600 mm的大型叠环式剪切仪上进行拉拔试验,研究了干密度对土工格栅与膨胀土界面拉拔性状的影响.结果表明:干密度较大时,土工格栅刚体平动及其速率增大时的拉拔力较大,峰值拉拔力较大,峰值时土工格栅的变形量较大;干密度较大时,筋土界面摩阻力-相对位移曲线更偏于弹塑性特征,其界面切向刚度较小;干密度对界面似摩擦角的影响显著,而对似粘聚力的影响较小.

A filling with dimension of 600 mm×600 mm×600 mm laminated shear test apparatus is adopted to carry out a series of pull-out tests,with HDPE uniaxial geogrid and PET biaxial geogrid,and the weathered expansive marlite in Xinxiang,the middle route of the South-to-North Water Transfer Project（SNWTP）,to investigate effect of dry density on behaviors of the interface between geogrids and compacted expansive soils.The results show that,with higher dry density,the pull-out force increases when the velocity of geogrid＇s rigid movement increases,and the peak pull-out force and the deformation of geogrid develops greater.Curve of interface friction and relative displacement tends to be elastoplastic behavior with high dry density;and the interface rigidity is smaller.The dry density has a significant effect on the interface quasi-friction angle,but unconspicuous effect on the quasi-cohesion.