1.1 本规程概述了使用脉冲回波法对土工膜进行超声波检测的设备和程序。 1.2 超声波在固体材料中的传播与材料的物理力学性能和条件有关。在超声波测试中，通常确定两种波传播特性:速度（基于波传播时间测量）和衰减（基于波振幅测量）。波传播速度用于确定材料的厚度、密度和弹性特性。 固体材料中的波衰减用于确定材料的微观结构特性。此外，还分析了波的频率特性，以研究测试材料的特性。行程时间、振幅和频率分布测量用于评估材料的状况，以识别固体材料中的损伤和缺陷。超声波测量也用于确定与试样接触的材料/介质的性质。测量在时间内进行- 域（时间与振幅）或频域（频率与振幅）。 1.3 一个或多个超声波传输特性的测量是基于特定测试程序的要求进行的。 1.4 以国际单位制表示的数值应视为标准。本标准不包括其他计量单位。 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====== 5.1 本规程涵盖了使用超声波检测对土工膜进行无损评估所需的测试安排、测量技术、采样方法和计算。 5.2 可以为特定的土工膜（针对特定的聚合物类型、特定的配方、特定的密度）确定波速。可以在速度与土工膜的密度和拉伸特性之间建立关系。试验方法中介绍了使用超声波测定聚乙烯密度的一个例子 D4883 速度测量可用于确定土工膜的厚度 ( 1. ， 2. ) 。 4. 传输波的传播时间和振幅可用于评估土工膜的状况，并识别土工膜中的缺陷，包括表面缺陷（例如划痕、切口）、内部缺陷（例如土工膜内的不连续性）和穿透整个土工膜厚度的缺陷（例如针孔） ( 3. ， 4. ) .土工膜片之间的结合可以使用行进时间、速度或阻抗测量来评估接缝 ( 5- 10 ) .实践中介绍了使用超声波测试通过行程时间和速度测量（导致厚度测量）来确定现场和工厂接缝完整性的示例 D4437 和 D4545 分别地超声波检测设备通常用于现场评估预制沥青土工膜的接缝 ( 11 ) 可以使用超声波测量及时监测土工膜的完整性。 注1: 由于施加的压力和探头尺寸等测试条件的差异，超声波测量和使用其他方法进行的测量之间可能存在差异。一个例子是超声波和机械厚度测量。 5.3 该方法适用于在实验室和现场对母材和接缝进行测试。测试持续时间非常短，因为通过土工膜的波传输发生在微秒内。

1.1 This practice provides a summary of equipment and procedures for ultrasonic testing of geomembranes using the pulse echo method. 1.2 Ultrasonic wave propagation in solid materials is correlated to physical and mechanical properties and condition of the materials. In ultrasonic testing, two wave propagation characteristics are commonly determined: velocity (based on wave travel time measurements) and attenuation (based on wave amplitude measurements). Velocity of wave propagation is used to determine thickness, density, and elastic properties of materials. Attenuation of waves in solid materials is used to determine microstructural properties of the materials. In addition, frequency characteristics of waves are analyzed to investigate the properties of a test material. Travel time, amplitude, and frequency distribution measurements are used to assess the condition of materials to identify damage and defects in solid materials. Ultrasonic measurements are used to determine the nature of materials/media in contact with a test specimen as well. Measurements are conducted in the time-domain (time versus amplitude) or frequency-domain (frequency versus amplitude). 1.3 Measurements of one or more ultrasonic wave transmission characteristics are made based on the requirements of the specific testing program. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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 This practice covers test arrangements, measurement techniques, sampling methods, and calculations to be used for nondestructive evaluation of geomembranes using ultrasonic testing. 5.2 Wave velocity may be established for particular geomembranes (for specific polymer type, specific formulation, specific density). Relationships may be established between velocity and both density and tensile properties of geomembranes. An example of the use of ultrasound for determining density of polyethylene is presented in Test Method D4883 . Velocity measurements may be used to determine thickness of geomembranes ( 1 , 2 ) . 4 Travel time and amplitude of transmitted waves may be used to assess the condition of geomembranes and to identify defects in geomembranes including surface defects (for example, scratches, cuts), inner defects (for example, discontinuities within geomembranes), and defects that penetrate the entire thickness of geomembranes (for example, pinholes) ( 3 , 4 ) . Bonding between geomembrane sheets can be evaluated using travel time, velocity, or impedance measurements for seam assessment ( 5- 10 ) . Examples of the use of ultrasonic testing for determining the integrity of field and factory seams through travel time and velocity measurements (resulting in thickness measurements) are presented in Practices D4437 and D4545 , respectively. An ultrasonic testing device is routinely used for evaluating seams in prefabricated bituminous geomembranes in the field ( 11 ) . Integrity of geomembranes may be monitored in time using ultrasonic measurements. Note 1: Differences may exist between ultrasonic measurements and measurements made using other methods due to differences in test conditions such as pressure applied and probe dimensions. An example is ultrasonic and mechanical thickness measurements. 5.3 The method is applicable to testing both in the laboratory and in the field for parent material and seams. The test durations are very short as wave transmission through geomembranes occurs within microseconds.