1.1 本规程描述了与现有试验方法一起用于确定收缩次数的程序 米 基于厚度、单位面积质量和纤维特性的机械粘结非织造土工织物 1.2 收缩数是非织造土工织物的一个特性，它与开口尺寸互补，以预测其过滤性能。它可用于区分开口尺寸相似但结构（厚度、重量、纤维直径等）不同的无纺土工织物。然而，在比较两种不同开口尺寸的产品时，需要更多的研究来评估其重要性。 1.3 在过滤应用中，需要以较高的置信度控制管道或堵塞问题，即在关键土壤中进行过滤应用时，应考虑收缩的数量。 1.4 本标准仅用于设计目的，不用于质量控制目的。 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建立适当的安全、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《国际标准、指南和建议制定原则决定》中确立的国际公认标准化原则制定的。 =====意义和用途====== 5.1 本规程提供了确定收缩次数的计算方法 米 无纺土工布（或复合材料层）。本标准不适用于机织土工布、针织土工布，热粘结土工布或任何其他类型的土工合成材料。 5.2 收缩的数量表示由三个或更多纤维界定的“窗口”的数量，土壤颗粒可以在其中迁移。已发现该值与解释具有相似开口尺寸但不同结构的无纺土工织物在不同土壤条件下的不同过滤行为有关（见 附录X1 详细信息）。 5.3 该值将用于过滤研究，以评估具有类似开口尺寸的各种非织造土工织物的过滤效率和有效性的预测（试验方法 第6767页 ). 5.4 解释 米 使用本标准计算时，应小心，因为- 编织结构可能不反映用于建立所提出方程的假设（参见 附录X1 详细信息）。

1.1 This practice describes the procedure used along with existing test methods to determine the number of constrictions m of mechanically bonded non-woven geotextiles, based on thickness, mass per unit area, and fiber properties 1.2 The number of constrictions is a property of non-woven geotextiles, which is complementary to opening size to predict their filtration behavior. It can be used to differentiate non-woven geotextiles with similar opening sizes but different structures (thickness, weight, fiber diameter, etc.). However, more research is needed to assess its significance when comparing two products with different opening sizes. 1.3 Consideration of the number of constrictions is relevant in filtration applications where piping or clogging concerns are to be controlled with a high level of confidence, that is, for filter applications in critical soils. 1.4 This standard is for design purposes only and is not intended for quality control purposes. 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 This practice provides a calculation method for determining the number of constrictions m of a non-woven geotextile (or of a layer of a composite material). This standard is not applicable to woven geotextiles, knitted geotextiles, heat-bonded geotextiles, or any other type of geosynthetic. 5.2 The number of constrictions represents the number of “windows” delimited by three or more fibers, in which soil particles could migrate. This value has been found to be relevant to explain the different filtration behaviors of non-woven geotextiles with similar opening sizes but different structures for various soil conditions (see Appendix X1 for details). 5.3 This value will be used in filtration research to evaluate the prediction of filtration efficiency and effectiveness of various non-woven geotextiles with similar opening sizes (Test Method D6767 ). 5.4 Interpretation of the significance of m as calculated using this standard shall be done with care, as some non-woven structures may not reflect the hypothesis used to establish the proposed equation (see Appendix X1 for details).