1.1 这些测试方法涵盖了在标准测试条件下，在未压缩状态下，根据介电常数测定土工织物导水性（透水性）的程序。包括三个程序:使用水流装置的恒定水头和下降水头法，以及使用气流装置的气流法。 1.2 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。 1.3 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。 1.4 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. 这些试验方法被认为是令人满意的土工布商业运输验收试验，因为这些方法已广泛用于验收试验行业。 5.1.1 如果在使用这些测试方法进行商业装运验收测试时，由于报告测试结果的差异而产生争议，买方和供应商应进行比较测试，以确定其实验室之间是否存在统计偏差。建议为调查偏差提供称职的统计协助。作为最低要求，双方应尽可能均匀地从大量相关类型的材料中选取一组试样。 然后，应将试样随机分配到每个实验室进行测试。两个实验室的平均结果应使用学生的 t -测试未配对数据和双方在测试开始前选择的可接受概率水平。如果发现偏差，必须找到并纠正其原因，或者买方和供应商必须同意根据已知偏差解释未来的测试结果。 5.1.2 当争议涉及使用方法B落差测试或方法C气流测试产生的测试结果时，应使用使用50 mm水头进行的方法A恒定水头测试作为仲裁方法。 5.1.3 当争议涉及方法C时，必须记录用于水流试验的实际水温，并且必须使用试验温度下的水粘度将气流转换为第节中所述的水流 16 ，无需应用温度校正。 5.1.4 介电常数是在隔离条件下可以通过土工织物的水量的指标。 5.1.5 由于可以使用土工布的应用和环境条件很多，在尝试将这些测试方法的结果应用于土工布的现场性能时，应小心。 5.2 由于使用的土工布厚度不同，因此根据其达西渗透系数进行评估可能会产生误导。在许多情况下，评估特定横截面积上给定水头下通过土工布的水量更为重要；这表示为介电常数。 5.3 如果单个土工织物的渗透性很重要，则可以计算与岩土工程相关的标称渗透系数。将介电常数乘以土工织物的标称厚度，由试验方法确定 D5199 ，得到了标称渗透系数。 注2: 使用标称厚度是因为在试验期间难以评估土工织物上的压力，因此难以在这些试验条件下确定织物的厚度。

1.1 These test methods cover procedures for determining the hydraulic conductivity (water permeability) of geotextiles in terms of permittivity under standard testing conditions, in the uncompressed state. Included are three procedures: the constant head and falling head methods using a water flow apparatus, and the air flow method using an air flow apparatus. 1.2 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. 1.3 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. 1.4 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 These test methods are considered satisfactory for acceptance testing of commercial shipments of geotextiles since the methods have been used extensively in the trade for acceptance testing. 5.1.1 In case of a dispute arising from differences in reported test results when using these test methods for acceptance testing of commercial shipments, the purchaser and the supplier should conduct comparative tests to determine if there is a statistical bias between their laboratories. Competent statistical assistance is recommended for the investigation of bias. As a minimum, the two parties should take a group of test specimens that are as homogeneous as possible and that are from a lot of material of the type in question. The test specimens should then be randomly assigned in numbers to each laboratory for testing. The average results from the two laboratories should be compared using Student's t -test for unpaired data and an acceptable probability level chosen by the two parties before the start of testing. If a bias is found, either its cause must be found and corrected, or the purchaser and the supplier must agree to interpret future test results in light of the known bias. 5.1.2 When the dispute involves test results produced with either the Method B falling head test or the Method C air flow test, the Method A constant head test performed with a 50 mm head should be used as the referee method. 5.1.3 When the dispute involves Method C, the actual water temperature used for the water flow tests must be recorded and the viscosity of water at the test temperature must be used in the conversion from the air flow to water flow as described in Section 16 , without the application of the temperature correction. 5.1.4 Permittivity is an indicator of the quantity of water that can pass through a geotextile in an isolated condition. 5.1.5 As there are many applications and environmental conditions under which a geotextile may be used, care should be taken when attempting to apply the results of these test methods to the field performance of a geotextile. 5.2 Since there are geotextiles of various thicknesses in use, evaluation in terms of their Darcy coefficient of permeabilities can be misleading. In many instances, it is more significant to evaluate the quantity of water that would pass through a geotextile under a given head over a particular cross-sectional area; this is expressed as permittivity. 5.3 If the permeability of an individual geotextile is of importance, a nominal coefficient of permeability, as related to geotechnical engineering, may be computed. By multiplying permittivity times the nominal thickness of the geotextile, as determined by Test Method D5199 , the nominal coefficient of permeability is obtained. Note 2: The nominal thickness is used as it is difficult to evaluate the pressure on the geotextile during the test, thereby making it difficult to determine the thickness of the fabric under these test conditions.