1.1 本试验方法涵盖了在恒定变形速率下，测定土工合成材料对土壤的剪切阻力或土工合成材料对另一种土工合成材料的剪切阻力的程序。 1.1.1 该测试方法旨在通过尝试模拟某些现场条件来指示所选样本的性能。从该方法获得的结果在适用于试验中考虑的特定条件方面可能受到限制。 1.2 本试验方法适用于所有土工合成材料，但土工合成粘土衬垫（GCL）除外，其在试验方法中有说明 D6243/D6243M . 1.3 由于剪切力和位移分布不均匀，该试验方法不适合建立试样的精确应力-应变关系。 1.4 以国际单位制或英寸-磅单位表示的数值应单独视为标准值。每个系统中规定的值可能不是精确的等效值；因此，每个系统应相互独立使用。将两个系统的值合并可能会导致不符合标准。 1.5 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户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（TBT）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》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 本试验方法中描述的用于测定土壤和土工合成材料或土工合成材料和土工合成材料界面的抗剪强度的程序旨在作为性能试验，为用户提供一组测试条件的设计值。试样和条件（包括法向应力）通常由用户选择。 5.2 本试验方法可用于土工合成材料商业装运的验收试验，但建议谨慎，如中所述 5.2.1 . 5.2.1 剪切阻力只能用实际试验条件表示（参见 注释2和 3. ). 确定的值可能是施加的法向应力、材料特性（例如，土工合成材料）、土壤性质、样品尺寸、含水量、排水条件、位移率、位移幅度和其他参数的函数。 注2: 如果验收测试需要使用土壤，用户必须提供土壤样本、土壤参数和直剪测试参数。出于验收目的的测试数据解释方法应由本测试方法的用户共同商定。 注3: 本试验方法下的试验应由具有土壤直剪试验资质且符合实践要求的实验室进行 D3740 尤其是由于测试结果可能取决于现场特定条件和测试条件。 5.2.2 本试验方法测量土工合成材料和支撑材料（底层）或土工合成材料和上覆材料（上层）之间的总剪切阻力。 总剪切阻力可能是材料组件滑动、滚动和联锁的组合。 5.2.3 本试验方法不区分单个机制，这些机制可能是所用土壤和土工合成材料、材料放置和水合方法、施加的法向应力和剪切应力、用于将土工合成材料固定到位的方法、剪切位移速率和其他因素的函数。应尽一切努力尽可能确定试样的剪切面积和失效模式。应注意，包括在测试后对样本进行仔细的目视检查，以确保测试条件代表所调查的条件。 5.2.4 实验室之间的精度信息不完整。在有争议的情况下，可以进行比较测试，以确定实验室之间是否存在统计偏差。 5.3 试验结果可用于土工合成材料应用的设计，包括但不限于:垃圾填埋场、采矿堆沥滤场、尾矿蓄水池、水坝和其他液压屏障、土工合成加筋挡土墙、路堤和基层的衬里和盖的设计；在将土工合成材料放置在斜坡上的应用中；用于确定土工合成材料重叠要求；或在土壤和土工合成材料之间或两种土工合成材料之间可能发生滑动的其他应用中。 5.4 由于试样安装、夹持表面和材料制备的差异，峰值强度和峰后强度发生的位移以及剪切应力-剪切位移曲线的形状可能因试验装置而异。本试验方法结果的使用者应注意，在指定位移下的结果可能无法在实验室中再现，并且本试验在峰值强度下测得的相对剪切位移可能与现场条件下峰值强度下的相对剪切位移不匹配。

1.1 This test method covers a procedure for determining the shear resistance of a geosynthetic against soil, or a geosynthetic against another geosynthetic, under a constant rate of deformation. 1.1.1 The test method is intended to indicate the performance of the selected specimen by attempting to model certain field conditions. Results obtained from this method may be limited in their applicability to the specific conditions considered in the testing. 1.2 The test method is applicable for all geosynthetics, with the exception of geosynthetic clay liners (GCLs), which are addressed in Test Method D6243/D6243M . 1.3 The test method is not suited for the development of exact stress-strain relationships for the test specimen due to the nonuniform distribution of shearing forces and displacement. 1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the 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 The procedure described in this test method for determination of the shear resistance of the soil and geosynthetic or geosynthetic and geosynthetic interface is intended as a performance test to provide the user with a set of design values for the test conditions examined. The test specimens and conditions, including normal stresses, are generally selected by the user. 5.2 This test method may be used for acceptance testing of commercial shipments of geosynthetics, but caution is advised as outlined in 5.2.1 . 5.2.1 The shear resistance can be expressed only in terms of actual test conditions (see Notes 2 and 3 ). The determined value may be a function of the applied normal stress, material characteristics (for example, of the geosynthetic), soil properties, size of sample, moisture content, drainage conditions, displacement rate, magnitude of displacement, and other parameters. Note 2: In the case of acceptance testing requiring the use of soil, the user must furnish the soil sample, soil parameters, and direct shear test parameters. The method of test data interpretation for purposes of acceptance should be mutually agreed to by the users of this test method. Note 3: Testing under this test method should be performed by laboratories qualified in the direct shear testing of soils and meeting the requirements of Practice D3740 , especially since the test results may depend on site-specific and test conditions. 5.2.2 This test method measures the total resistance to shear between a geosynthetic and a supporting material (substratum) or a geosynthetic and an overlying material (superstratum). The total shear resistance may be a combination of sliding, rolling, and interlocking of material components. 5.2.3 This test method does not distinguish between individual mechanisms, which may be a function of the soil and geosynthetic used, method of material placement and hydration, normal and shear stresses applied, means used to hold the geosynthetic in place, rate of shear displacement, and other factors. Every effort should be made to identify, as closely as practicable, the sheared area and failure mode of the specimen. Care should be taken, including close visual inspection of the specimen after testing, to ensure that the testing conditions are representative of those being investigated. 5.2.4 Information on precision among laboratories is incomplete. In cases of dispute, comparative tests to determine whether a statistical bias exists among laboratories may be advisable. 5.3 The test results can be used in the design of geosynthetic applications including, but not limited to: the design of liners and caps for landfills, mining heap leach pads, tailings impoundments, cutoffs for dams and other hydraulic barriers, geosynthetic-reinforced retaining walls, embankments, and base courses; in applications in which the geosynthetic is placed on a slope; for determination of geosynthetic overlap requirements; or in other applications in which sliding may occur between soil and a geosynthetic or between two geosynthetic materials. 5.4 The displacement at which peak strength and post-peak strength occurs and the shape of the shear stress versus shear displacement curve may differ considerably from one test device to another due to differences in specimen mounting, gripping surfaces, and material preparation. The user of results from this test method is cautioned that results at a specified displacement may not be reproducible across laboratories and that the relative shear displacement measured in this test at peak strength may not match relative shear displacement at peak strength in a field condition.