压实黏土的三轴拉伸特性试验研究

Experimental study on triaxial tensile property of compacted clay

研制了一种新型的卧式三轴拉压试验仪。该仪器采用应变控制式加载方式,可消除土体自重的影响,轴向刚度大,可以测定三轴条件下土体拉伸破坏全过程应力位移曲线。对糯扎渡和双江口高心墙堆石坝心墙土料进行三轴拉伸(伸长)试验,发现黏土试样的破坏可能表现为低室压时的纯拉断、高室压时的纯剪切以及中室压时的张拉-剪切复合破坏三种形式。根据试验结果,提出了一种适用于压实黏土三轴拉伸破坏的联合强度准则。

A new-type of horizontal triaxial tension-compression apparatus for soil test was developed.It adopts strain-control loading mode and can eliminate the influence of self weight of soil specimen.It has a large axial rigidity and can be used to obtain a full stress-displacement curve of compacted clay in tensile failure under triaxial condition.Application to the triaxial tensile（extensile） test on the core clay materials of the Nuozhadu and Shuangjiangkou high earth-rockfill dams reveals three failure modes,i.e.pure tensile failure under low cell pressure,pure shear failure under high cell pressure,and tensile-shear coupled failure under middle cell pressure.Based on the test results,a joint strength criterion for triaxial tensile failure of compacted clay is proposed.