1.1 该试验方法包括使用轴向载荷的应变控制应用，在完整、重塑或重建条件下测定粘性土的无侧限抗压强度。 1.2 该试验方法提供了粘性土强度的总应力近似值。 1.3 本试验方法仅适用于在试验加载部分不会排水（由于变形而从土壤中排出的水）的粘性材料，以及在去除围压后仍能保持固有强度的粘性材料（如粘土或粘性土）。干的和易碎的土壤、裂缝或变化的材料、淤泥、泥炭和沙子不能用这种方法进行测试，以获得有效的无侧限抗压强度值。 1.4 本试验方法不能替代试验方法 2850英镑 . 注1: 试验方法涵盖了具有侧向约束的粘性土的松散、不排水强度的测定 2850英镑 看见 5.2 以获取更多信息。 1.5 单位-- 以国际单位制或英寸磅单位表示的数值应单独视为标准。每个系统中规定的值可能不是完全相等的；因此，每个系统应独立使用。将两个系统的值合并可能导致不符合标准。以SI以外的单位报告试验结果不应被视为不符合本标准。 1.5.1 处理英寸磅单位时使用英寸磅单位的重力系统。在这个系统中，磅（lbf）表示力（重量）的单位，而质量的单位是蛞蝓。除非涉及动态（F=ma）计算，否则未给出合理的段塞单元。 1.5.2 工程/建筑行业的常见做法是同时使用磅来表示质量单位（lbm）和力单位（lbf）。 这种做法隐含地结合了两个独立的单位系统；绝对系统和引力系统。在一个标准中同时使用两套独立的英寸磅单位在科学上是不可取的。如前所述，本标准包括以英寸-磅为单位的重力系统，不使用/表示段塞质量单位。但是，使用天平或天平记录质量磅（lbm）或以lbm/ft为单位记录密度 3. 不得视为不符合本标准。 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指南 D6026 ，除非被本标准取代。 1.6.1 用于规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。 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因素；并且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 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》中确立的国际公认的标准化原则制定的。 ====意义和用途====== 5.1 无侧限抗压试验的主要目的是快速测量那些具有足够内聚力的土壤的抗压强度，以便在无侧限状态下进行试验。试验在非自由排水土壤上进行，应变速率足够高，使土壤在加载过程中不会排水。试样的饱和度会影响剪切过程中的排水条件，从而影响试验结果。 5.2 由于试验是在无侧限试样上进行的，因此该试验方法不试图复制加载前的原位应力状态。此外，剪切过程中的排水条件也不确定。因此，该试验方法提供了一个不排水抗剪强度指标。 5.3 当根据试验方法进行试验时，具有滑面或裂隙结构的土壤样品、某些类型的黄土、非常软的粘土、干燥和易碎的土壤以及各种材料的样品，或含有大量淤泥或沙子的样品，或者两者都有（所有这些通常都表现出粘性），通常显示出更高的抗剪强度 2850英镑 此外，当根据试验方法进行试验时，非饱和土通常会表现出不同的抗剪强度 2850英镑 . 5.4 如果在同一样品的完整状态和重塑状态下进行测试，则可以确定材料的灵敏度。这种测定灵敏度的方法仅适用于在重塑状态下能够保持稳定试样形状的土壤。 注2: 对于无法保持稳定形状的土壤，试验方法 D4648/D4648米 或测试方法 2850英镑 可以用于确定灵敏度。 注3: 本标准产生的结果的质量取决于执行该标准的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 通常被认为能够胜任和客观的测试/取样/检查。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但不是全部因素的方法。

1.1 This test method covers the determination of the unconfined compressive strength of cohesive soil in the intact, remolded, or reconstituted condition, using strain-controlled application of the axial load. 1.2 This test method provides an approximate value of the strength of cohesive soils in terms of total stresses. 1.3 This test method is applicable only to cohesive materials which will not expel or bleed water (water expelled from the soil due to deformation) during the loading portion of the test and which will retain intrinsic strength after removal of confining pressures, such as clays or clayey soils. Dry and crumbly soils, fissured or varved materials, silts, peats, and sands cannot be tested with this method to obtain valid unconfined compressive strength values. 1.4 This test method is not a substitute for Test Method D2850 . Note 1: The determination of the unconsolidated, undrained strength of cohesive soils with lateral confinement is covered by Test Method D2850 . See 5.2 for additional information. 1.5 Units— The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. Reporting of test results in units other than SI shall not be regarded as nonconformance with this standard. 1.5.1 The gravitational system of inch-pound units is used when dealing with inch-pound units. In this system, the pound (lbf) represents a unit of force (weight), while the unit for mass is slugs. The rationalized slug unit is not given, unless dynamic (F = ma) calculations are involved. 1.5.2 It is common practice in the engineering/construction profession to concurrently use pounds to represent both a unit of mass (lbm) and of force (lbf). This practice implicitly combines two separate systems of units; the absolute and the gravitational systems. It is scientifically undesirable to combine the use of two separate sets of inch-pound units within a single standard. As stated, this standard includes the gravitational system of inch-pound units and does not use/present the slug unit for mass. However, the use of balances or scales recording pounds of mass (lbm) or recording density in lbm/ft 3 shall not be regarded as nonconformance with this standard. 1.6 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026 , unless superseded by this standard. 1.6.1 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. 1.7 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 ====== 5.1 The primary purpose of the unconfined compression test is to quickly measure the compressive strength for those soils that possess sufficient cohesion to permit testing in the unconfined state. The test is performed on non-free draining soils at a strain rate sufficiently high enough such that the soil does not expel water during loading. The degree of saturation of the test specimen can affect drainage conditions during shearing, which may affect the test results. 5.2 Since testing is performed on an unconfined specimen, this test method does not attempt to replicate an in situ state of stress prior to loading. Further, drainage conditions during shearing are not certain. Therefore, this test method provides an index of undrained shear strength. 5.3 Samples of soils having slickensided or fissured structure, samples of some types of loess, very soft clays, dry and crumbly soils and varved materials, or samples containing significant portions of silt or sand, or both (all of which usually exhibit cohesive properties), frequently display higher shear strengths when tested in accordance with Test Method D2850 . Also, unsaturated soils will usually exhibit different shear strengths when tested in accordance with Test Method D2850 . 5.4 If tests on the same sample in both its intact and remolded states are performed, the sensitivity of the material can be determined. This method of determining sensitivity is suitable only for soils that can retain a stable specimen shape in the remolded state. Note 2: For soils that will not retain a stable shape Test Method D4648/D4648M or Test Method D2850 may be used to determine sensitivity. Note 3: The quality of the result produced by this standard 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/sampling/inspection. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some, but not all, of those factors.