1.1 本试验方法包括使用轴向荷载的应变控制应用，测定完整、重塑或重建条件下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在总应力方面的近似值。 1.3 本试验方法仅适用于在试验加载期间不会排水（由于变形或压实而从土壤中排出的水）且在消除围压后仍能保持固有强度的粘性材料，如粘土或胶结土。无法使用此方法测试干燥和易碎的土壤、裂缝或凹凸不平的材料、淤泥、泥炭和沙子，以获得有效的无侧限抗压强度值。 注1: 试验方法包括测定具有侧向约束的粘性土的未固结、不排水强度 D2850 . 1.4 本试验方法不能替代试验方法 D2850 . 1.5 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。 1.5.1 本试验方法中用于规定如何收集/记录和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测试方法的范围。 1.6 以国际单位制或英寸-磅单位表示的数值应单独视为标准值。每个系统中规定的值可能不是精确的等效值；因此，每个系统应相互独立使用。将两个系统的值合并可能会导致不符合标准。 1.6.1 在处理英寸磅单位时，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，而质量的单位是段塞。除非涉及动态（F=ma）计算，否则未给出合理化的段塞单元。 1.6.2 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（lbf）。这隐含地结合了两个独立的单元系统；也就是说，绝对系统和引力系统。在一个标准中结合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，本标准包括英寸-磅单位的重力系统，不使用/呈现质量的段塞单位。然而，使用天平或天平记录磅质量（lbm）或记录密度（lbm/ft） 3. 不应视为不符合本标准。 1.7 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====== 5.1 无侧限抗压试验的主要目的是快速获得具有足够凝聚力的土壤的抗压强度测量值，以允许在无侧限状态下进行试验。 5.2 当根据试验方法进行试验时，具有光滑或裂缝结构的土壤样品、某些类型的黄土、极软粘土、干燥和易碎的土壤和变硬材料的样品，或含有大量粉土或砂或两者（所有这些通常表现出粘性）的样品，通常显示出较高的抗剪强度 D2850 . 此外，当按照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 D2850 . 5.3 如果在同一样品的完整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，采用十字板剪切试验或试验方法 D2850 可用于确定灵敏度。 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 通常认为能够胜任和客观的测试/采样/检查。 本标准的用户应注意遵守惯例 D3740 本身不能确保可靠的结果。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 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 or compaction) during the loading portion of the test and which will retain intrinsic strength after removal of confining pressures, such as clays or cemented soils. Dry and crumbly soils, fissured or varved materials, silts, peats, and sands cannot be tested with this method to obtain valid unconfined compression strength values. Note 1: The determination of the unconsolidated, undrained strength of cohesive soils with lateral confinement is covered by Test Method D2850 . 1.4 This test method is not a substitute for Test Method D2850 . 1.5 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026 , unless superseded by this standard. 1.5.1 The procedures used to specify how data are collected/recorded and calculated in this test method are regarded as the industry standard. In addition, they are representative of the significant digits that should generally 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 commensurate with these considerations. It is beyond the scope of this test method to consider significant digits used in analysis methods for engineering design. 1.6 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. 1.6.1 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. 1.6.2 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 implicitly combines two separate systems of units; that is, the absolute system and the gravitational system. 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. 1.7 This standard does not purport to address all of the safety problems, 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 ====== 5.1 The primary purpose of the unconfined compression test is to quickly obtain a measure of compressive strength for those soils that possess sufficient cohesion to permit testing in the unconfined state. 5.2 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 . 5.3 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, a vane shear test or Test Method D2850 can 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. Users of this standard are cautioned that compliance with Practice D3740 does not in itself ensure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.