褶皱土工膜+针刺钠基膨润土防水毯复合衬里的剪切试验研究

Experimental research on the shear characteristics of the composite liner consisting of wrinkled geomembrane and needle punched geosynthetic clay liner

防渗工程中土工膜的褶皱现象普遍存在,然而目前关于土工膜界面剪切特性的研究大都忽略了褶皱的影响。以糙面土工膜(GM)和针刺钠基膨润土防水毯(GCL)组成的复合衬里为研究对象,利用水化变形试验证实两步水化法能有效地加速含褶皱GM+GCL复合衬里的水化步骤,使用大尺寸温控水浴直剪仪对含褶皱GM+GCL复合衬里的剪切特性进行了试验研究。通过将含褶皱GM+GCL复合衬里的剪切特性与无褶皱复合衬里进行对比分析,揭露了GM褶皱对复合衬里剪切特性的影响机制。GM褶皱的存在使得GM+GCL复合衬里的剪切应力-位移曲线产生较大差异,并使得低压下复合衬里的抗剪强度明显降低。GM褶皱使复合衬里产生明显的渐进破坏效应,复合衬里内部能出现多种破坏模式共存的现象。

Wrinkles in geomembrane are common among anti-seepage engineering.However,the wrinkling effect has been neglected in most of the current studies on the interface shear properties of geomembrane.The composite liner consists of a textured geomembrane(GM)and a needle punched geosynthetic clay liner(GCL)was taken as the research object,and the hydration deformation tests confirmed that the two-step hydration method was effective in accelerating the hydration of the wrinkled GM+GCL composite liner.The shear properties of the wrinkled GM+GCL composite liner was studied by a large-scale temperature-controlled submerged direct shear apparatus.The shear characteristic of the wrinkled GM+GCL composite liner was analyzed compared to the shear results of the composite liner without GM wrinkle,and the influence mechanism of GM wrinkles on the shear characteristics of the composite liner was clarified.Experimental researches show that the existence of GM wrinkle will change the shear stress-displacement curve of the GM+GCL composite liner a lot,and the peak shear strength of the composite liner under low normal stress can be obviously reduced by the GM wrinkle.Significant progressive failure could be observed in the wrinkled GM+GCL composite liner.Besides,multiple failure modes can coexist inside the composite liner under unique normal stress as well.