1.1 本试验方法包括通过CERCHAR耐磨性指数（CAI）法测定岩石的耐磨性。该测试方法包括使用两个测试设备中的一个，在规定的10mm距离内，测量由刚破碎或锯切的岩石表面划伤引起的锥形钢触针尖端的磨损和已知的洛氏硬度。 1.2 本试验方法适用于刚破碎的岩石表面；然而，当不能获得令人满意的岩石表面时，锯切表面被覆盖。 1.3 触针的洛氏硬度（HR）会对结果产生深远影响。本试验方法的重点是每次试验的HRC值为55 ( 1. , 2. ) . 2. 然而，在某些情况下，可以使用具有不同洛氏硬度的触针。因此，该测试方法包括对具有不同洛氏硬度的触针的讨论。 1.3.1 洛氏硬度（HR）值基于材料的压痕硬度。洛氏试验， 第18页 ，测量大载荷（大载荷）下压头的穿透深度，与预载荷（小载荷）下的穿透深度相比。 ( 3. ) 有不同的刻度，用一个字母（a到F）表示，使用不同的载荷或压头。结果是一个标注为HRA、HRB、HRC等的无量纲数字，其中最后一个字母是相应的洛氏硬度计，在本试验方法中为硬度计C，用于硬化钢。 1.4 基本上，CERCHAR测试是对触针尖端和岩石样品表面相对不同硬度的测量。触针尖端由具有已知洛氏硬度的钢制成。实验表明，CAI与触针硬度成反比。使用相同钢型触针但硬度不同的测试结果需要归一化为标准触针硬度 ( 2. ) . 1.5 划痕距离应限制在10 mm。通常，85 % 在划痕长度的前2mm期间发生触针磨损。其余15个 % 在划痕长度的最后8mm期间发生触针磨损。因此，当划痕长度的变化保持在±0之间时，划痕长度从测试到测试的微小变化不会显著影响触针的总磨损和产生的CAI。 5. 长度mm ( 3. ) . 1.6 所有观测值和计算值应符合实践中制定的有效数字和四舍五入准则 D6026 . 1.6.1 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。所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；并且通常的做法是增加或减少报告数据的有效数字以与这些考虑相称。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。 1.7 单位- 以国际单位表示的值应视为标准值。本标准不包括其他计量单位。 1.8 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建立适当的安全、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 CERCHAR测试和相关的CAI是在法国夏令营研究中心（CERCHAR）对机械挖掘机应用需求增加的时候开发的 ( 5. ) CAI用于评估机械开挖岩石的耐磨性。岩石磨蚀性决定了圆盘刀具的性能、更换速度以及随后的隧道成本。地下开挖方法的进步，尤其是隧道掘进机（TBM）的使用，需要了解岩石的磨蚀性。耐磨性表示岩石的行为特征，而不是基本的物理或机械特性。 5.2 CAI试验最初是在天然断裂表面上进行的。对于非均质岩石类型，如砾岩、粗粒花岗岩或片岩，使用锤子进行机械破碎无法获得合适的新鲜试验表面。在这些情况下，可接受使用金刚石锯切割的“光滑”表面的CAI值，但应通过 等式2 或 等式3 在报告之前 ( 4. ) . 5.3 原始CERCHAR装置的测试速度约为10 mm/s，而西部CERCHAR装置的测试速率约为1 mm/s。两种测试速度的CAI值 ( 4. ) 估计是相等的。 注1: 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 通常认为能够胜任和客观的测试和取样。这些实践的使用者应注意遵守实践 D3740 其本身不能保证可靠的结果。可靠的结果取决于许多因素；实践 D3740 提供了评估其中一些因素的方法。

1.1 This test method covers the determination of the abrasiveness of rock by the CERCHAR Abrasiveness Index (CAI) method. The test method consists of measuring the wear on the tip of steel stylus with a cone shape and known Rockwell Hardness, caused by scratching against a freshly broken or saw cut rock surface for a prescribed 10 mm distance using one of the two test apparatus. 1.2 This test method is intended for freshly broken rock surfaces; however, saw cut surfaces are covered for when a satisfactory rock surface cannot be obtained. 1.3 The Rockwell Hardness (HR) of the stylus can have a profound effect on the results. The focus of this test method is an HRC value of 55 for every test ( 1 , 2 ) . 2 However, there are situations where styli with different Rockwell Hardness can be used. Therefore, this test method includes discussions on stylus with different Rockwell Hardness. 1.3.1 The Rockwell hardness (HR) value is based on the indentation hardness of a material. The Rockwell test, E18 , measures the depth of penetration of an indenter under a large load (major load) compared to the penetration made by a preload (minor load). ( 3 ) There are different scales, denoted by a single letter (A to F), that use different loads or indenters. The result is a dimensionless number noted as HRA, HRB, HRC, etc., where the last letter is the respective Rockwell scale which in this test method is the scale C, which is for harden‐steel. 1.4 Basically, the CERCHAR test is a measurement of the relative different hardness of stylus tip and rock specimen surface. The stylus tip is made of steel having a known Rockwell Hardness. Experiments have shown that CAI varies inversely with stylus hardness. Test results with the same steel type stylus but with different hardness need to be normalized to standard stylus hardness ( 2 ) . 1.5 The scratch distance shall be limited to 10 mm. In general, 85 % of the stylus wear occurs during the first 2 mm of scratch’s length. The remaining 15 % of the stylus wear occurs during the last 8 mm of the scratch’s length. Therefore, minor variation in the scratch’s length from test to test doesn’t significantly affect the total stylus wear and the resulting CAI when variation in scratch length is kept between ±0.5 mm in length ( 3 ) . 1.6 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026 . 1.6.1 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. 1.7 Units— The values stated in SI units are to be regarded as standard. No other units of measurement are included in 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 The CERCHAR test and associated CAI were developed at a time of more demand for application of mechanical excavation machines at the Laboratoire du Center d' Études et Recherches des Charbonnages de France (CERCHAR) ( 5 ) . CAI is used to assess the abrasiveness of rock for mechanical excavation. Rock abrasiveness governs the performance of disc cutters, the rate of its replacement and therefore subsequent tunnel costs. Advances in methods of underground excavation, in particular the use of the tunnel boring machine (TBM), necessitates knowledge of rock abrasiveness. Abrasiveness expresses a behavioral characteristic of rock rather than a fundamental physical or mechanical property. 5.2 CAI tests were originally carried out on natural broken surfaces. In heterogeneous rock types such as conglomerates, coarse grained granite or schistose rock, suitable fresh test surfaces are not achieved by mechanical breakage using a hammer. In these cases CAI values for “smooth” surfaces cut with a diamond saw are acceptable for use but shall be normalized by Eq 2 or Eq 3 before they can be reported ( 4 ) . 5.3 The test velocity for the Original CERCHAR apparatus is approximately 10 mm/s and 1 mm/s for the West CERCHAR apparatus. The CAI values obtained for both testing velocities ( 4 ) are estimated to be equal. Note 1: 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.