In this paper, a comprehensive laboratory study was done on the shear behavior of the interface between geomembrane and an adjacent sandy layer using a modified direct shear test apparatus. The key parameters for this investigation included roughness of geomembrane surface, sedimentation angles of a specifically selected sand, and applied normal stress, for which a total of 162 tests were conducted, excluding reliability tests. As an indicator of all the mentioned samples, a formulation was obtained using response surface methodology (RSM) model. The results of the study were in line with previously published findings in this subject matter. The test results indicated that friction angle is highly influenced by the sand anisotropy where the maximum frictional resistance occurred at an orthogonal angle and decreased with the increase in the degree of induced anisotropy. The variations were more noticeable for the sand than sand–geomembrane interface with a minimum for the roughest interface that confirmed the reduction in anisotropy effects on shear strength with the increase in surface roughness.

中文翻译：

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固有各向异性对砂-纹理土工膜界面剪切行为的影响

在本文中，使用改进的直剪试验装置对土工膜与相邻砂层之间界面的剪切行为进行了全面的实验室研究。本次调查的关键参数包括土工膜表面粗糙度、特定沙子的沉降角和施加的法向应力，共进行了162次测试，不包括可靠性测试。作为所有提到的样品的指标，使用响应面方法 (RSM) 模型获得了一个公式。该研究的结果与之前发表的有关该主题的发现一致。试验结果表明，摩擦角受砂体各向异性影响较大，最大摩擦阻力出现在正交角处，并随着诱导各向异性程度的增加而减小。砂的变化比砂 - 土工膜界面更明显，最粗糙的界面最小，这证实了随着表面粗糙度的增加，各向异性对剪切强度的影响降低。