1.1 本试验方法涵盖了在恒定变形速率下测定土工合成粘土衬垫（GCL）的内部剪切阻力或GCL与相邻材料之间的界面剪切阻力的程序。 1.2 本试验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。 1.3 本试验方法适用于所有GCL。重塑或原状土样可用于试验装置中。见测试方法 D5321/D5321M 用于非GCL土工合成材料的界面剪切试验。请参阅指南 D7702/D7702M 有关使用本试验方法获得的直剪结果评估的可用信息总结。 1.4 由于剪力和位移分布不均匀，本试验方法不适合在试样内建立精确的应力-应变关系。 1.5 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不一定是精确的等价物；因此，为确保符合本标准，每个系统应独立使用，且两个系统的值不得组合。 1.6 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。 1.7 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 本测试方法中描述的用于确定GCL或GCL界面剪切阻力的程序旨在作为性能测试，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 该测试方法可用于GCL商业装运的验收测试，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。本标准用户应相互同意用于验收的测试数据解释方法。 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GCL内或GCL与相邻材料之间的总剪切阻力。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GCL的函数、材料放置和水合方法、施加的法向应力和剪切应力、用于将GCL固定到位的方法、水平位移速率和其他因素。 应尽一切努力尽可能准确地识别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GCL应用的设计，包括但不限于垃圾填埋场衬垫和盖的设计、水坝的截流和其他液压屏障。 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的不同而有很大差异。本标准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，并且本试验中在峰值强度下测得的相对水平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 internal shear resistance of a geosynthetic clay liner (GCL) or the interface shear resistance between the GCL and an adjacent material under a constant rate of deformation. 1.2 This test method is intended to indicate the performance of the selected specimen by attempting to model certain field conditions. 1.3 This test method is applicable to all GCLs. Remolded or undisturbed soil samples can be used in the test device. See Test Method D5321/D5321M for interface shear testing of non-GCL geosynthetics. See Guide D7702/D7702M for a summary of available information related to the evaluation of direct shear results obtained using this test method. 1.4 This test method is not suited for the development of exact stress-strain relationships within the test specimen due to the nonuniform distribution of shearing forces and displacement. 1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined. 1.6 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. 1.7 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 for the GCL or the GCL 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 GCLs, 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 standard. 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 within a GCL or between a GCL and adjacent material. 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 GCL used, method of material placement and hydration, normal and shear stresses applied, means used to hold the GCL in place, rate of horizontal displacement, and other factors. Every effort should be made to identify, as closely as is 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 between laboratories is incomplete. In cases of dispute, comparative tests to determine whether a statistical bias exists between laboratories may be advisable. 5.3 The test results can be used in the design of GCL applications, including but not limited to, the design of liners and caps for landfills, cutoffs for dams, and other hydraulic barriers. 5.4 The displacement at which peak strength and post-peak strength occur 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 standard is cautioned that results at a specified displacement may not be reproducible across laboratories and that the relative horizontal displacement measured in this test at peak strength may not match relative shear displacement at peak strength in a field condition.