1.1 本试验方法中的细粒土仅限于含量不超过15%的土壤 % 细砂（100 % 通过425 μm（40号）筛且不超过15 % 保留在75 μm（200号）筛）。 本标准末尾有“变更摘要”一节。 1.2 本试验方法提供了在排水条件下进行扭转环剪试验的程序，以确定细粒土的残余抗剪强度。本试验方法通过以受控位移速率剪切重组、过度固结、预剪切试样，直到在由仪器配置确定的单个剪切表面上建立恒定排水剪切阻力。 1.3 在本试验中，试样沿一个方向旋转，直到建立恒定或残余剪切阻力。 使用试样的平均半径将旋转量转换为位移，并将其乘以移动的度数和0.0174。 1.4 可以使用完整的试样或具有自然剪切表面的试样进行测试。然而，获得自然滑动面样本、确定现场剪切方向以及在环剪装置中修剪和对齐通常非水平剪切面是困难的。因此，本试验方法的重点是使用复原试样来确定残余强度。可以实现无限量的连续剪切位移，以获得环形剪切装置中的残余强度条件。 1.5 可从该试验方法中获得剪切应力-位移关系。然而，剪切应力- 由于剪切带的高度未知，因此无法通过本试验方法确定应变关系或任何相关量，例如模量，因此无法确定准确或具有代表性的剪切应变。 1.6 设计分析中有效法向应力的选择和抗剪强度参数的确定由要求测试的专业人员或办公室负责。通常，在多阶段试验中，向试样施加三个或更多有效正应力，或者可以为每个有效正应力使用一个新试样，以确定排水残余破坏包络线。 1.7 以国际单位制表示的数值应视为标准值。括号中给出的值仅供参考，不被视为标准值。 括号中给出的值是英寸-磅单位的数学转换。以国际单位制以外的单位报告试验结果不应视为不符合本标准。 1.8 所有测量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。 1.8.1 用于指定如何在标准中收集/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。 1.9 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。 1.10 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. 环形剪切试验适用于相对快速地测定排水残余剪切强度，因为通过薄试样的排水路径较短，剪切期间剪切表面的横截面积恒定，单向旋转位移无限，以及在不同有效法向应力下测试一个试样的能力，以获得与剪切方向平行的粘土颗粒，从而获得残余剪切强度包络线。 5.2 该装置允许在排水剪切之前对重组样本进行过度固结和预剪切。重建样本的过度固结和预剪切显著减少了达到残余状态所需的水平位移，因此减少了土壤挤压、壁摩擦和其他问题（Stark和Eid，1993） 3. . 这模拟了先前存在的剪切面，沿该剪切面可以调动排水残余强度。 5.3 环形剪切试样是环形的，因此从内边缘到外边缘的角位移不同。在残余条件下，整个试样的剪切强度是恒定的，因此试样内外边缘之间的剪切应力差可以忽略不计。 注1: 尽管本试验方法中包含精度和偏差声明: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 通常认为能够进行合格测试。本试验方法的使用者应注意遵守规程 D3740 无法确保可靠的测试。可靠的测试取决于几个因素；实践 D3740 提供了一种评估其中一些因素的方法。

1.1 Fine-grained soils in this Test Method are restricted to soils containing no more than 15 % fine sand (100 % passing the 425 μm (No. 40) sieve and no more than 15 % retained on the 75 μm (No. 200) sieve). A Summary of Changes section appears at the end of this standard. 1.2 This test method provides a procedure for performing a torsional ring shear test under a drained condition to determine the residual shear strength of fine-grained soils. This test method is performed by shearing a reconstituted, overconsolidated, presheared specimen at a controlled displacement rate until the constant drained shear resistance is established on a single shear surface determined by the configuration of the apparatus. 1.3 In this test, the specimen rotates in one direction until the constant or residual shear resistance is established. The amount of rotation is converted to displacement using the average radius of the specimen and multiplying it by numbers of degrees traveled and 0.0174. 1.4 An intact specimen or a specimen with a natural shear surface can be used for testing. However, obtaining a natural slip surface specimen, determining the direction of field shearing, and trimming and aligning the usually non-horizontal shear surface in the ring shear apparatus is difficult. As a result, this test method focuses on the use of a reconstituted specimen to determine the residual strength. An unlimited amount of continuous shear displacement can be achieved to obtain a residual strength condition in a ring shear device. 1.5 A shear stress-displacement relationship may be obtained from this test method. However, a shear stress-strain relationship or any associated quantity, such as modulus, cannot be determined from this test method because the height of the shear zone unknown, so an accurate or representative shear strain cannot be determined. 1.6 The selection of effective normal stresses and determination of the shear strength parameters for design analyses are the responsibility of the professional or office requesting the test. Generally, three or more effective normal stresses are applied to a test specimen in a multi-stage test or a new specimen can be used for each effective normal stress to determine the drained residual failure envelope. 1.7 The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information only and are not considered standard. The values given in parentheses are mathematical conversions to inch-pound units. Reporting of test results in units other than SI shall not be regarded as nonconformance with this standard. 1.8 All measured and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026 unless superseded by this standard. 1.8.1 The procedures used to specify how data are collected/recorded or calculated in the 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. 1.9 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. 1.10 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 ring shear test is suited to the relatively rapid determination of drained residual shear strength because of the short drainage path through the thin specimen, the constant cross-sectional area of the shear surface during shear, unlimited rotational displacement in one direction, and the capability of testing one specimen under different effective normal stresses to obtain clay particles that are oriented parallel to the direction of shear to obtain residual shear strength envelope. 5.2 The apparatus allows a reconstituted specimen to be overconsolidated and presheared prior to drained shearing. Overconsolidation and preshearing of the reconstituted specimen significantly reduces the horizontal displacement required to reach a residual condition, and therefore, reduces soil extrusion, wall friction, and other problems (Stark and Eid, 1993) 3 . This simulates a preexisting shear surface along which the drained residual strength can be mobilized. 5.3 The ring shear test specimen is annular so the angular displacement differs from the inner edge to the outer edge. At the residual condition, the shear strength is constant across the specimen so the difference in shear stress between the inner and outer edges of the specimen is negligible. 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 testing. Users of this test method are cautioned that compliance with Practice D3740 does not ensure reliable testing. Reliable testing depends on several factors; Practice D3740 provides a means of evaluating some of those factors.