1.1 此练习提供了一种计算2 % 使用试验方法测定0.5 mm至5 mm（20密耳至200密耳）聚乙烯土工膜的割线模量 6693天/6693米 . 1.2 这种做法将通过标准化推导应力-应变曲线上进行计算的点的方法，促进类似材料的模量比较。 1.3 以国际单位制表示的数值应视为标准。括号中给出的值仅供参考。 1.4 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。 1.5 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====== 4.1 在用聚乙烯土工膜进行拉伸试验时，通常不清楚在哪里画切线来确定弹性模量。这个问题导致测试结果有很大的变化，因此，这一特性在比较中不可靠。 4.2 基于2的割线模量 % 在材料之间进行比较、质量控制以及在非标准环境下比较同一样品时，应变是有用的。 4.3 割线模量是弹性模量的近似值，并且通常导致比弹性模量的值更低的值。 4.4 尽管测量2的技术 % 割线模量在这里描述，其他百分比的割线模量可以通过这种做法来测量。

1.1 This practice presents a technique for calculating the 2 % secant modulus for polyethylene geomembranes between 0.5 mm and 5 mm (20 mil and 200 mil) using Test Method D6693/D6693M . 1.2 This practice will facilitate modulus comparisons of similar materials by standardizing the method for deriving the points on the stress-strain curve from which the calculations are performed. 1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only. 1.4 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. 1.5 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 ====== 4.1 Where to draw the tangent to determine the modulus of elasticity is often unclear when performing tensile tests with polyethylene geomembranes. This problem results in a wide variation in test results and, therefore, makes this property unreliable for comparisons. 4.2 A secant modulus based on 2 % strain can be useful when making comparisons between materials, in quality control, and in comparing the same sample after being subjected to a nonstandard environment. 4.3 Secant modulus is an approximation of modulus of elasticity and generally results in a lower value than that for the modulus of elasticity. 4.4 Although the technique for measuring 2 % secant modulus is described here, other percent secant moduli can be measured by this practice.