堆石坝面防渗膜-垫层料界面力学特性试验研究

堆石坝面防渗土工膜与垫层料界面的力学特性关系到防渗体的抗滑稳定性以及整个大坝的安全性.采用土工合成材料界面直剪拉拔仪分别对复合膜和HDPE纯膜与无砂混凝土及聚合物透水混凝土两种垫层料、加糙PVC膜与表面复合细骨料聚合物透水混凝土的界面力学特性进行了试验研究.试验结果表明：HDPE纯膜与两种垫层界面的剪应力-剪位移关系具有不同程度的应变软化特征,界面峰值强度高于残余强度;而复合膜与两种垫层界面的剪应力-剪切位移关系无明显软化现象;复合土工膜与两种垫层界面抗剪强度高于纯膜与两种垫层界面的抗剪强度;聚合物透水混凝土和无砂混凝土与复合膜界面抗剪强度差别不大,聚合物透水混凝土界面抗剪强度略低;糙面PVC膜与表面为细骨料聚合物透水混凝土的咬合力较大.

Experimental Study of Mechanical Properties of Interfaces between Geomembrane Applied to Rockfill Dam and Cushion Materials

The mechanical properties of interface between geomembrane used to control seepage in rockfill dams and cushion layer are related to the stability of impervious body and the security of the entire dam. By u- sing geosynthetics interface direct shear-pullout apparatus, the interface characteristics between two geomem- brane including composite geomembrane and HDPE and two kinds of cushion materials including porous con- crete and polymer concrete and that between reinforced PVC and polyurethane concrete are studied. The re- sults show that. the shear stress - shear displacement relationship of the interface between HDPE and two kinds of cushion layers have different degree strain softening characteristics that the peak strength of interface is higher than the residual strength of it~ while there is no obvious strain softening phenomenon occurred in the shear stress-shear displacement relationship of the interface between composite geomembrane and two kinds of cushion layers. The shear strength of the interface between composite geomembrane and two kinds of cushion layers is higher than that of the interface between HDPE and two kinds of cushion layers. The shear strength of the interface between polymer concrete and composite geomembrane is similar with that of the in- terface between porous concrete and composite geomembrane. The shear strength of the interface between polymer concrete and composite geomembrane is a little lower. The cohesion of reinforced PVC and polymer concrete whose surface is fine aggregate is larger.