1.1 这些试验方法包括测定无粘性自由排水土壤的最小指数干密度/单位重量。密度或单位重量前的形容词“干”在标题中省略，本标准的其余部分与第节中给出的适用定义一致 3. 关于术语。 1.2 单位制: 1.2.1 本标准中所述的测试仪器是使用重量或英寸-磅系统中的数值开发和制造的。因此，以英寸-磅为单位的试验装置尺寸和质量被视为标准。 1.2.2 工程专业中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。科学上不希望同时使用两套独立的英寸- 单一标准内的磅单位。本试验方法是在处理英寸-磅系统时使用单位重力系统编写的。在该系统中，磅（lbf）表示力（重量）的单位。然而，天平或天平测量质量；必须计算重量。在英寸-磅系统中，通常假设1 lbf等于1 lbm。虽然报告密度不被视为不符合本标准，但应计算和报告单位重量，因为结果可用于确定力或应力。 1.2.3 术语密度和单位重量经常互换使用。密度是单位体积的质量，而单位重量是单位体积的力。在本标准中，密度仅以国际单位制表示。密度确定后，单位重量以国际单位制或英寸-磅单位计算，或以两者为单位计算。 1.3 提供了三种替代方法来确定最小指数密度/单位重量，如下所示: 1.3.1 方法A——使用漏斗浇注装置或手勺将材料放入模具中。 1.3.2 方法B-通过提取充满土壤的管将材料沉积到模具中。 1.3.3 方法C 2. -通过倒置量筒沉积材料。 1.4 使用的方法应由要求测试的机构指定。如果没有规定方法，应以方法A的规定为准。试验方法A是与试验方法程序一起使用的确定最小指数密度/单位重量的首选程序 D4253 . 方法B和C用于指导与特殊研究结合使用的测试，尤其是在没有足够的材料可用于0.100 ft的情况下 3. （2830厘米 3. )或0.500英尺 3. (14 200厘米 3. )方法A要求的模具。 1.5 这些试验方法适用于可能含有15 %, 通过200号（75）的土壤颗粒的干质量- μm）筛，前提是它们仍然具有无粘性、自由排水特性（标称筛尺寸符合规范要求） E11 ). 1.5.1 方法A适用于土壤，其中100 %, 按干质量计算，土壤颗粒通过3英寸。（75 mm）筛，最多可包含30 %, 按干质量计算，保留在1 1. / 2. -英寸（37.5毫米）筛。 1.5.2 方法B适用于土壤，其中100 %, 土壤颗粒的干质量通过 3. / 4. -英寸（19.0-mm）筛。 1.5.3 方法C仅适用于细砂和中砂，其中100 %, 土壤颗粒的干质量通过 3. / 8. -在中。（9.5-mm）筛，最多可含有10 %, 以干质量计，保留在10号（2.00-mm）筛上的土壤颗粒。 1.5.4 就这些试验方法而言，土壤应被视为自然产生的无粘性土壤、加工颗粒、或天然土壤的复合物或混合物，或天然颗粒和加工颗粒的混合物，只要它们是自由的- 排水。 1.6 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 . 1.6.1 为了将测量值或计算值与规定限值进行比较，测量值或计算值应四舍五入至规定限值中最接近的小数或有效数字。 1.6.2 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。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。 1.7 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 无粘性土壤的密度/单位重量可通过现场各种原位方法或通过实验室土壤样本测量物理尺寸和质量来确定。无粘性土壤的干密度/单位重量本身并不一定能揭示土壤是松散的还是密实的。 5.2 相对密度/容重表示无粘性土壤在标准实验室程序定义的最松散和最密实条件下的密实度。只有从相对密度/容重的可能变化范围来看，干密度/容重才能与用于将土壤置于压实填土中的压实力相关，或指示体积变化和应力- 承受外部荷载时土壤的应变趋势。 5.3 通过这些试验方法不一定能获得绝对最小密度/单位重量。 注1: 此外，有公布的数据表明，这些测试方法具有高度的可变性。 4. 然而，通过仔细校准设备，并仔细注意适当的测试程序和技术，可以大大降低可变性。 5.4 标准模具的使用( 6.2.1 )对于大多数需要最小指数密度/容重测试的土壤而言，这是令人满意的。特殊模具( 6.2.2 )仅当试验结果与设计或特殊研究结合使用，且土壤不足，无法使用标准模具时，方可使用。应谨慎使用此类试验结果，因为使用特殊模具获得的最小指数密度/单位重量可能与使用标准模具获得的结果不一致。 注2: 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/采样/检查等。本标准的用户应注意遵守惯例 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 These test methods cover the determination of the minimum-index dry density/unit weight of cohesionless, free-draining soils. The adjective “dry” before density or unit weight is omitted in the title and remaining portions of this standards to be be consistent with the applicable definitions given in Section 3 on Terminology. 1.2 System of Units: 1.2.1 The testing apparatus described in this standard has been developed and manufactured using values in the gravimetric or inch-pound system. Therefore, test apparatus dimensions and mass given in inch-pound units are regarded as the standard. 1.2.2 It is common practice in the engineering profession to concurrently use pounds to represent both a unit of mass (lbm) and a unit 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. This test method has been written using the gravitational system of units when dealing with the inch-pound system. In this system, the pound (lbf) represents a unit of force (weight). However, balances or scales measure mass; and weight must be calculated. In the inch-pound system, it is common to assume that 1 lbf is equal to 1 lbm. While reporting density is not regarded as nonconformance with this standard, unit weights should be calculated and reported since the results may be used to determine force or stress. 1.2.3 The terms density and unit weight are often used interchangeably. Density is mass per unit volume, whereas unit weight is force per unit volume. In this standard, density is given only in SI units. After the density has been determined, the unit weight is calculated in SI or inch-pound units, or both. 1.3 Three alternative methods are provided to determine the minimum index density/unit weight, as follows: 1.3.1 Method A—Using a funnel pouring device or a hand scoop to place material in mold. 1.3.2 Method B—Depositing material into a mold by extracting a soil filled tube. 1.3.3 Method C 2 —Depositing material by inverting a graduated cylinder. 1.4 The method to be used should be specified by the agency requesting the test. If no method is specified, the provisions of Method A shall govern. Test Method A is the preferred procedure for determining minimum index density/unit weight as used in conjunction with the procedures of Test Methods D4253 . Methods B and C are provided for guidance of testing used in conjunction with special studies, especially where there is not enough material available to use a 0.100 ft 3 (2830 cm 3 ) or 0.500 ft 3 (14 200 cm 3 ) mold as required by Method A. 1.5 These test methods are applicable to soils that may contain up to 15 %, by dry mass, of soil particles passing a No. 200 (75-μm) sieve, provided they still have cohesionless, free-draining characteristics (nominal sieve dimensions are in accordance with Specification E11 ). 1.5.1 Method A is applicable to soils in which 100 %, by dry mass, of soil particles pass a 3-in. (75-mm) sieve and which may contain up to 30 %, by dry mass, of soil particles retained on a 1 1 / 2 -inch (37.5-mm) sieve. 1.5.2 Method B is applicable to soils in which 100 %, by dry mass, of soil particles pass a 3 / 4 -inch (19.0-mm) sieve. 1.5.3 Method C is applicable only to fine and medium sands in which 100 %, by dry mass, of soil particles pass a 3 / 8 -in. (9.5-mm) sieve and which may contain up to 10 %, by dry mass, of soil particles retained on a No. 10 (2.00-mm) sieve. 1.5.4 Soils, for the purposes of these test methods, shall be regarded as naturally occurring cohesionless soils, processed particles, or composites or mixtures of natural soils, or mixtures of natural and processed particles, provided they are free-draining. 1.6 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026 . 1.6.1 For purposes of comparing a measured or calculated value(s) to specified limits, the measured or calculated value(s) shall be rounded to the nearest decimal or significant digits in the specified limits. 1.6.2 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 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 and health practices and determine the applicability of regulatory limitations prior to use. ====== Significance And Use ====== 5.1 The density/unit weight of a cohesionless soil may be determined by various in-place methods in the field or by the measurement of physical dimensions and masses by laboratory soil specimens. The dry density/unit weight of a cohesionless soil does not necessarily, by itself, reveal whether the soil is loose or dense. 5.2 Relative density/unit weight expresses the degree of compactness of a cohesionless soil with respect to the loosest and densest condition as defined by standard laboratory procedures. Only when viewed against the possible range of variation, in terms of relative density/unit weight, can the dry density/unit weight be related to the compaction effort used to place the soil in a compacted fill or indicate volume change and stress-strain tendencies of soil when subjected to external loading. 5.3 An absolute minimum density/unit weight is not necessarily obtained by these test methods. Note 1: In addition, there are published data to indicate that these test methods have a high degree of variability. 4 However, the variability can be greatly reduced by careful calibration of equipment, and careful attention to proper test procedure and technique. 5.4 The use of the standard molds ( 6.2.1 ) has been found to be satisfactory for most soils requiring minimum index density/unit weight testing. Special molds ( 6.2.2 ) shall only be used when the test results are to be applied in conjunction with design or special studies and there is not enough soil to use the standard molds. Such test results should be applied with caution, as minimum index densities/unit weights obtained with the special molds may not agree with those that would be obtained using the standard molds. Note 2: 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 , generally, are considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard 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.