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复合土工膜是由高分子聚合物制成的一种平面柔性薄膜并在其侧面黏有织物的土工合成材料,因其具有良好的防渗性能及施工简便等优点而得到广泛应用。针对我国水电工程中大量运用复合土工膜快速修建高水头土石围堰过程中普遍存在拉断、撕裂等集中破坏渗漏现象,分析发现复合土工膜在刚性基础锚固或防渗墙接头等工程结构物的软硬交界区域因应变集中且超出其极限延伸率而导致结构性的损坏,而目前计算方法均难以反映该性状。从复合土工膜材料力学性能、复合膜与周围填料及锚固接头相互作用机制出发,参照面板坝周边缝单元有限元处理模式,建立反映复合土工膜应变集中的“周边膜”单元的几何与物理描述方法,并将其本构关系及位移模式植入三维有限元程序,计算获取了高度为85 m的白鹤滩水电站上游围堰复合土工膜应变集中部位的应变状态,为高水头、大变形等复杂受力条件下复合土工膜的安全利用和推广起到有益的理论支持作用。
The composite geomembrane is a kind of flat and flexible film made of macromolecule polymer and glued on the side of the geotextile fabric. It has been widely used because of its good impermeability and easy construction. In view of the common phenomenon of concentrated breakage such as pull-off and tear in the rapid construction of high-head rock-soil cofferdam by using a large number of composite geomembranes in hydropower projects in our country, it is found that the composite geomembrane in the rigid foundation anchors or impervious wall joints and other engineering structures The hard and soft interface region of the object is structurally damaged due to the concentration of strain and beyond its ultimate elongation, which is hardly reflected by the current calculation methods. Based on the mechanical properties of the composite geomembrane material and the interaction between the composite membrane and the surrounding fillers and the anchorage joint, the geometrical and mechanical properties of the “perimeter membrane” unit reflecting the strain concentration of the geomembrane Physical description method, and the constitutive relationship and displacement model embedded in the three-dimensional finite element program to obtain the height of 85 m Baihetan Hydropower Station upstream cofferdam composite geomembrane strain concentration concentrated strain site for the high head, large deformation Such as complex geometries under the conditions of the safe use and promotion of composite geomembranes play a useful theoretical support.