1.1本规程涵盖了岩石力学领域中使用的各种类型伸长计的描述、应用、选择、安装、数据收集和数据简化。 1.2第节介绍了每种类型引伸计系统的局限性 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SI值仅供参考。 1.4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。 1.5 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，应与专业判断结合使用。 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。 1.6 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和健康实践，并确定监管限制的适用性。 ====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、收敛等的大多数装置。 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、潜在不稳定斜坡上的安全监测装置，并用于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。 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 extensometers used in the field of rock mechanics. 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 SI values given in parentheses are provided for information purposes only. 1.4 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. 1.5 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 judgement. 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. 1.6 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 and health practices and determine the applicability of regulatory limitations prior to use. ====== 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 installation. No single instrument is suitable for all applications. 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.