1.1 本规程涵盖了岩石力学领域中使用的各种接触式引伸计的描述、应用、选择、安装、数据收集和数据简化。此处不包括激光或其他非接触式伸长计。 1.2 每种类型引伸计系统的局限性见第节 5. . 1.3 以英寸-磅为单位的数值应视为标准值。括号中给出的值是到国际单位制的数学转换，仅供参考，不被视为标准值。如适用，添加“以英寸以外的单位报告测试结果- pound不应被视为不符合本标准。 1.4 所有观察值和计算值应符合实践中确定的有效数字和舍入准则 D6026 . 1.4.1 本标准中用于规定如何收集/记录或计算数据的程序被视为行业标准。此外，它们代表了通常应保留的有效数字。使用的程序不考虑材料变化、获取数据的目的、特殊目的研究或用户目标的任何考虑因素；通常的做法是增加或减少报告数据的有效位数，以与这些考虑因素相称。 考虑工程设计分析方法中使用的有效数字超出了本标准的范围。 1.5 本标准的文本引用了提供解释材料的注释和脚注。这些注释和脚注（不包括表和图中的注释和脚注）不应视为本标准的要求。 1.6 本实践提供了一组用于执行一个或多个特定操作的说明。本文件不能取代教育或经验，应与专业判断一起使用。并非本指南的所有方面都适用于所有情况。 本ASTM标准不代表或取代必须根据其判断给定专业服务的充分性的谨慎标准，也不应在不考虑项目的许多独特方面的情况下应用本文件。本文件标题中的“标准”一词仅表示该文件已通过ASTM共识程序获得批准。 1.7 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。 1.8 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====== 4.1 引伸计广泛应用于工程领域，包括用于测量位移、分离、沉降、收敛等的大多数设备。 4.2 对于隧道仪器，伸长计通常用于测量顶板和侧壁移动，并定位隧道开口周围的张拉拱区。 4.3 引伸计还广泛用作隧道、地下洞室、潜在不稳定斜坡的安全监测装置，以及监测岩石支护系统的性能。 4.4 应根据预期用途、所需测量精度、预期变形范围和安装细节选择伸长计。没有一种仪器适用于所有应用。 4.5 在岩石施工应用中，精确测量通常可以识别岩石运动的显著、可能危险的趋势； 然而，精确测量远不如整体运动模式重要。 4.6 伸长计的数据收集可以是简单的或低技术的，例如在仪器位置手动读数，也可以是复杂的或高技术的，其中有现场采集的电子读数，可以在仪器位置下载，也可以传输到数据收集和分析中心。 4.7 了解每种类型引伸计之间的优缺点和成本很重要。在手动读数的情况下，可能收集不到太多的数据，重要数据可能会丢失，读数的人可能会受到伤害，并且可能无法在最需要数据或数据变得更重要时安全地继续收集数据。 然而，随着系统变得更加复杂，通过电子数据收集，收集的数据可以更安全地完成，提供可能遗漏的重要数据，并允许进行更及时、更准确的实时数据分析。 4.8 当某些开挖要求进行非常精确的测量时，例如，确定隧道开口周围的张拉拱区，应使用可在安装后现场调整的引伸计。在所有情况下，除了传感器的灵敏度外，还应给出通过校准确定的伸长计精度。 注1: 尽管本试验方法中包含精度和偏差声明，但本试验方法的精度取决于执行人员的能力以及所用设备和设施的适用性。符合实践标准的机构 D3740 通常认为能够胜任和客观测试。这些试验方法的使用者应注意遵守规程 D3740 本身不能确保可靠的结果。可靠的测试取决于许多因素；实践 D3740 提供了一种评估其中一些因素的方法。

1.1 This practice covers the description, application, selection, installation, data collecting, and data reduction of the various types of contact type extensometers used in the field of rock mechanics. Laser or other non-contact extensometers are not covered here. 1.2 Limitations of each type of extensometer system are covered in Section 5 . 1.3 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. Add if appropriate, “Reporting of test results in units other than inch-pound shall not be regarded as nonconformance with this standard. 1.4 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026 . 1.4.1 The procedures used to specify how data are collected/recorded or calculated in this standard are regarded as the industry standard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do not consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the user’s objectives; and it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations. It is beyond the scope of this standard to consider significant digits used in analysis methods for engineering design. 1.5 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard. 1.6 This practice offers a set of instructions for performing one or more specific operations. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process. 1.7 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. 1.8 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 Extensometers are widely used in the field of engineering and include most devices used to measure displacements, separation, settlements, convergence, and the like. 4.2 For tunnel instrumentation, extensometers are generally used to measure roof and sidewall movements and to locate the tension arch zone surrounding the tunnel opening. 4.3 Extensometers are also used extensively as safety monitoring devices in tunnels, in underground cavities, on potentially unstable slopes, and in monitoring the performance of rock support systems. 4.4 An extensometer should be selected on the basis of its intended use, the preciseness of the measurement required, the anticipated range of deformation, and the details accompanying the installation. No single instrument is suitable for all applications. 4.5 In applications for construction in rock, precise measurements will usually allow the identification of significant, possibly dangerous, trends in rock movement; however, precise measurement is much less important than the overall pattern of movement. 4.6 Data collection of extensometers can be simple or low tech, such as manual readings at the instrument location, or complex or high tech where there are electronic readings taken at the site and either downloaded at the instrument locations or transmitted to a data collection and analysis center. 4.7 It is important to realize the pros and cons and costs between each type of extensometers. In the case of manual readings, not as much data may be collected, important data may be missed and the person taking the readings may be put in harm’s way and may not be able to safely continue collecting data just when the data is needed the most or becomes more important. Whereas, with electronic data collection as the system becomes more sophisticated, the data collected can be done more safely, provide important data that might be missed, and may allow for real-time data analyses that are timelier and more accurate. 4.8 When very accurate measurements are dictated by certain excavations, for example, the determination of the tension arch zone around a tunnel opening, extensometers which can be adjusted in the field after installation shall be used. In all cases, the accuracy of extensometers, either determined through calibration, should be given in addition to the sensitivity of the transducers. Note 1: Notwithstanding the statements on precision and bias contained in this test method, the precision of this test method is dependent on the competence of the personnel performing it and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing. Users of these test methods are cautioned that compliance with Practice D3740 does not in itself ensure reliable results. Reliable testing depends on many factors; Practice D3740 provides a means of evaluating some of those factors.