复合土工膜-垫层材料界面摩擦特性试验研究

Experimental study on interface friction characteristics of composite geomembrane-cushion

复合土工膜防渗结构界面摩擦特性对工程的安全稳定性至关重要。为探寻复合土工膜-垫层界面摩擦特性,进行了室内直剪摩擦试验、斜板试验、室内拖板试验及现场原位试验,并统计分析一布一膜、二布一膜与砂浆垫层及砂砾石垫层的界面摩擦性能。结果表明:对于不同垫层材料,砂砾石垫层界面摩擦特性较优,比砂浆界面的摩擦角和凝聚力分别大5.0°和4.2 kPa;对不同类型的复合土工膜,二布一膜比一布一膜的界面摩擦角和凝聚力分别大3.4°和1.2 kPa;在不同试验中,直剪摩擦试验与斜板试验结果相近,与拖板试验相比摩擦角偏小约30%,凝聚力偏低约4~6 kPa;拖板试验结果与原位试验相近。因此,在防渗结构的设计中,垫层宜采用散粒体材料,复合土工膜宜选用二布一膜,并以拖板试验结果进行评定。

The interfacial friction of composite geomembrane impermeable structures plays an important role in the safe and stable operation of an engineering project.In order to explore the interfacial friction characteristics of composite geomembrane-cushion,the indoor direct shear friction test,inclined plate test,indoor towing plate test and in situ test were carried out to statistically analyze the interfacial friction properties between two different geomembranes and cushions,including one piece of cloth&one piece of film,two pieces of cloth&one piece of film as the geomabranes,mortar and gravels as the cushions.The results show that for different cushion materials,the interfacial friction characteristics of sand and gravel cushion was better,its friction angle was 5.0°larger than that of mortar,and the cohesion was 4.2 kPa higher;for different types of composite geomembrane,the interfacial friction angle of two pieces of cloth&one piece of film was 3.4°larger than that of one piece of cloth&one piece of film,and the cohesion was 1.2 kPa higher.In different tests,the results of the direct shear test were closer to those of the inclined plate test;however the friction angle of the direct shear test was about 30%smaller and the cohesion was about 4-6 kPa lower compared with the towing plate test.The results of the towing plate test were similar to those of the in situ test.Therefore,it is favorable to choose granular material as the cushion,and two pieces of cloth&one piece of film as the composite geomembrane in the design of the anti-seepage structure,and the towing plate test is a better choice for the evaluation of its performance.