高面膜土石坝防渗结构中土工膜弯折（褶皱）试验研究

Experimental study on geomembrane bending (folding) in anti-seepage structure of membrane-faced rockfill dam

针对面膜土石坝防渗结构设计与施工过程中存在防渗土工膜弯折(褶皱)问题,将弯折定性分为结构性弯折和非结构性弯折两种类型,为定量评价弯折作用造成的损伤及其规律,基于稳定性理论的薄板(壳)理论推演了影响土工膜弯曲变形的计算参数,并在理论分析的基础上自主研发一套试验装置。试验方案选用两种不同PVC土工膜作为试验材料,取90°最大弯折角度进行试验研究,并模拟4℃库水温度试验环境,试验结果表明弯折作用造成土工膜力学性能指标衰减,弯折作用120 d后,SY-GM土工膜断裂强度衰减度达到58.71%。根据试验数据分析成果,提出了增大弯折曲率半径和减小曲面弯折角度结构措施降低指标衰减度。

In view of the problem of bending(folding) of anti-seepage geomembrane in the design and construction of the anti-seepage structure of membrane-faced rockfill dam, the bending nature is divided into two types: structural bending and non-structural bending. In order to quantitatively evaluate the damage caused by the bending and its laws, the parameters affecting the bending deformation of geomembrane are deduced based on the thin plate(shell) theory of stability theory, and a set of test equipment is independently developed on the basis of theoretical analysis. Two different PVC geomembranes are selected as the experimental materials, and under the maximum bending angle of 90 degrees, the 4℃ water temperature test environment is simulated. The test results show that the bending effect causes the attenuation of mechanics performance index of the geomembrane. After the bending effect of 120 days, the attenuation degree of fracture strength of SY-GM type geomembrane reaches 58.71%. Based on the analysis results of experimental data, some measures are proposed to reduce the attenuation degree of the index by increasing the bending radius of curvature and reducing the bending angle of curved surface.