1.1 该试验方法包括测量土工膜对垂直于样品初始平面施加的力的平面外响应。 1.2 当土工膜变形到规定的几何形状（球体或椭球体的弧）时，提供公式将测试数据转换为双轴拉伸应力-应变值。这些公式不能用于其他几何形状。对于其他几何形状，可以获得变形与压力的比较数据。 1.3 该试验方法需要一个大直径的压力容器（610 mm）。从这种测试方法获得的信息可能比许多小规模指数测试更适合用于设计目的。 1.4 以国际单位制表示的数值应视为标准。 本标准不包括其他计量单位。 1.5 本标准并不旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ====意义和用途====== 5.1 已安装的土工膜会受到来自多个方向的力，包括垂直于土工膜表面的力。 土工膜的平面外变形可能有助于评估底土沉降可能有问题的承台材料。 5.2 与其他相对较小的指数测试相比，该测试的失效机制可能有所不同，并且可能有利于设计目的。 5.3 在预计会出现局部沉降的应用中，此测试可被视为性能测试。 5.4 对于土工膜不能按照本试验方法规定的方式变形的应用，应将本试验方法视为指数试验。 5.5 由于执行此测试所需的时间较长，因此将其视为质量控制测试并不实用。

1.1 This test method covers the measurement of the out-of-plane response of a geomembrane to a force that is applied perpendicular to the initial plane of the sample. 1.2 When the geomembrane deforms to a prescribed geometric shape (arc of a sphere or ellipsoid), formulations are provided to convert the test data to biaxial tensile stress-strain values. These formulations cannot be used for other geometric shapes. With other geometric shapes, comparative data on deformation versus pressure is obtained. 1.3 This test method requires a large-diameter pressure vessel (610 mm). Information obtained from this test method may be more appropriate for design purposes than many small-scale index tests. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 Installed geomembranes are subjected to forces from more than one direction, including forces perpendicular to the surfaces of the geomembrane. Out-of-plane deformation of a geomembrane may be useful in evaluating materials for caps where subsidence of the subsoil may be problematic. 5.2 Failure mechanisms on this test may be different compared to other relatively small-scale index tests and may be beneficial for design purposes. 5.3 In applications where local subsidence is expected, this test can be considered a performance test. 5.4 For applications where geomembranes cannot be deformed in the fashion this test method prescribes, this test method should be considered an index test. 5.5 Due to the time involved to perform this test, it is not considered practical as a quality control test.