1.1 本试验方法包括在室温下测定岩石物质或垂直于完整各向同性圆柱岩石试样纵轴的不连续性的直接抗拉强度。 1.2 本标准不包括非各向同性甚至横观各向同性试样。 1.3 圆柱形岩石样本可从现场钻取岩芯或将岩块运至实验室，并在那里获得钻取岩芯样本。 1.4 本标准不包括除圆柱形试样以外的试样形状，如狗骨头形状。 1.5 试样可在恒定载荷或变形速率下进行测试。 1.6 以国际单位制表示的数值应视为标准值。括号中提供的值仅供参考。 1.7 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 除非被本标准取代。 1.8 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。 1.9 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====== 5.1 岩石的拉伸比压缩弱得多。因此，在确定岩石结构的破坏条件时，许多研究人员将组分岩石的抗拉强度用作结构的破坏强度。 岩石的直接拉伸应力是确定岩石抗拉强度的最基本测试。然而，直接拉伸试验通常会在沿试样纵轴的最薄弱环节处断裂，无论是岩石物质还是比相邻岩石物质弱的任何不连续性。除非直接拉伸试验的目的是获得穿过不连续面的强度，否则试验结果是保守的，更能代表岩石物质尺度下的拉伸强度。看见 注释2 了解更多重要信息和使用信息。 注2: 这些实践产生的结果的质量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 通常认为能够胜任客观的测试和采样。提醒这些实践的用户遵守实践 D3740 本身并不能保证可靠的结果。可靠的结果取决于许多因素；实践 D3740 提供了一种评估其中一些因素的方法。

1.1 This test method covers the determination of the direct tensile strength of the rock substance or discontinuities normal to the longitudinal axis of intact, isotropic cylindrical rock specimens at room temperature. 1.2 Non-isotropic or even transversely isotropic specimens are not covered by this standard. 1.3 Cylindrical rock specimens can be drill core from the field or rock blocks transported to the laboratory and drill core specimen obtained there. 1.4 Specimen shapes other than cylindrical specimens, such as dog bone-shaped, are not covered by this standard. 1.5 Test specimens may be tested under constant load or deformation rate. 1.6 The values stated in SI units are to be regarded as standard. The values provided in parenthesis are for information only. 1.7 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026 unless superseded by this standard. 1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use.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. 1.9 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 Rock is much weaker in tension than in compression. Thus, in determining the failure condition for a rock structure, many investigators employ the tensile strength of the component rock as the failure strength for the structure. Direct tensile stressing of rock is the most basic test for determining the tensile strength of rock. However, direct tensile tests will typically break at the weakest link along the longitudinal axis of the specimen, whether it is the rock substance or any discontinuity that is weaker than the adjacent rock substance. Unless the purpose of the direct tension tests is to get the strength across discontinuities the test results are on the conservative side and are more representative of the tensile strength at the rock substance scale. See Note 2 for additional significance and use information. Note 2: The quality of the result produced by these practices is dependent upon 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 and sampling. Users of these practices are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.