1.1 这些试验方法包括使用试验方法在实验室测量冻融对压实或完整土壤样本导水性的影响 D5084 和一个柔性壁渗透仪，用于测定导水率。这些试验方法没有提供对已经经历冻融条件的原位土壤进行取样或测试的步骤。试验方法A使用一个样本进行冷冻/解冻后的每个导水率测定，而试验方法B使用一个样本进行整个试验方法（即，相同的样本用于每个导水率）。 1.2 这些试验方法可用于完整试样（块状或薄壁）或实验室压实试样，并应用于初始导水率小于或等于1E的土壤- 5米/秒[3.94 E-4英寸/秒]（1E-3厘米/秒）( 注1 ). 注1: 最大初始导水率为1 E-5 m/s[3.94 E-4 in/s]。这也应适用于最终水力传导率。预计如果初始导水率为1 E-5 m/s（3.94 E-4 in./s），则最终导水率不会发生显著变化（增加）（即大于1 E-5 m/s）（3.94 E-4 in./s）。 1.3 使用本试验方法测试的土壤样本可进行三维冻融（本文称为三维）或一维冻融（本文称为一维）。（关于一维冻结与三维冻结的讨论，请参阅Zimie和LaPlante或Othman等人。 2. 3. ) 1.4 使用本试验方法测试的土壤样本可以在封闭系统（即在冻结期间无法获得外部供水）或开放系统中进行测试。 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 . 1.5.1 用于规定如何在标准中收集/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。 考虑到工程数据分析方法中使用的有效数字，这超出了测试方法的范围。 1.6 单位- 以国际单位制或英寸-磅单位（括号内）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。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试验方法。 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、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（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====== 4.1 本试验方法仅识别自然土壤冻融引起的导水率变化。 4.2 当使用本试验方法确定实验室压实试样的适当含水量（即，干、湿或最佳含水量）时，用户应负责( 注释2 ). 注2: 通常做法是在最佳含水量或高于最佳含水量的条件下建造粘土衬里和覆盖层。 最佳含水量的压实干燥试样通常不包含因冻融而产生的较大孔径，因为由于样品中缺少水，冻融的影响最小化。因此，冻融对导水率的影响最小，或者导水率可能略有增加。 3. 4.3 请求者必须提供有关试验期间施加的有效应力的信息，特别是用于确定最终导水率的信息。使用试验方法允许的高有效应力（即35 kPa[5 psi D5084 )可以降低已经增加的导水率，从而降低最终导水率值。冻融对压实土壤水力传导率的长期影响尚不清楚。 冻融引起的导水率增加可能是暂时的。例如，垃圾经过冻融后放置在填埋场土壤衬垫上的废物施加的上覆压力可能会减小导致导水性增加的裂缝和孔隙的大小。不知道压力是否足以克服宏观增加的导水率，使土壤恢复到其原始导水率（冻融前）。对于表土压力较低的填埋场覆盖物等情况，冻融引起的导水率增加可能是永久性的。因此，在确定有效应力时，请求者必须考虑测试方法的应用。 4.4 试样应冷冻至 −15°C[5°F]，除非请求者另有明确指示。Othman等人对此进行了记录 3. 初始值（即0到 −15°C[32°F至5°F]）冻结条件对水力传导率的影响最为显著。冻结速率和极限温度应模拟现场条件。已经表明，超冷冻（即在非常低的温度和非常短的时间内冻结试样）会产生错误的结果。 4.5 解冻后的试样温度和解冻速率应模拟现场条件。在烘箱中解冻试样（即过热）会产生错误的结果。 4.6 据Othman等人 3. 冻融效应通常在第10次循环中出现，因此建议至少进行10次冷冻- 应进行解冻循环，以确保测量冻融的全部影响。如果在10次冻融循环后，导水率值仍在增加，则应继续试验方法（即，应进行更多的冻融循环）。 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 laboratory measurement of the effect of freeze-thaw on the hydraulic conductivity of compacted or intact soil specimens using Test Method D5084 and a flexible wall permeameter to determine hydraulic conductivity. These test methods do not provide steps to perform sampling of, or testing of, in situ soils that have already been subjected to freeze-thaw conditions. Test Method A uses a specimen for each hydraulic conductivity determination that is subjected to freeze/thaw while Test Method B uses one specimen for the entire test method (that is, the same specimen is used for each hydraulic conductivity). 1.2 These test methods may be used with intact specimens (block or thin-walled) or laboratory compacted specimens and shall be used for soils that have an initial hydraulic conductivity less than or equal to 1E-5 m/s [3.94 E-4 in./s] (1E-3 cm/s) ( Note 1 ). Note 1: The maximum initial hydraulic conductivity is given as 1 E-5 m/s [3.94 E-4 in./s]. This should also apply to the final hydraulic conductivity. It is expected that if the initial hydraulic conductivity is 1 E-5 m/s (3.94 E-4 in./s), then the final hydraulic conductivity will not change (increase) significantly (that is, greater than 1 E-5 m/s) (3.94 E-4 in./s). 1.3 Soil specimens tested using this test method can be subjected to three-dimensional freeze-thaw (herein referred to as 3-d) or one-dimensional freeze-thaw (herein referred to as 1-d). (For a discussion of one-dimensional freezing versus three-dimensional freezing, refer to Zimmie and LaPlante or Othman, et al. 2, 3 ) 1.4 Soil specimens tested using this test method can be tested in a closed system (that is, no access to an external supply of water during freezing) or an open system. 1.5 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026 . 1.5.1 The procedures used to specify how data are collected/recorded and 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 the test methods ro consider significant digits used in analysis methods for engineering data. 1.6 Units— The values stated in SI units or inch-pound units (presented in brackets) 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 test method. 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 ====== 4.1 This test method identifies the changes in hydraulic conductivity as a result of freeze-thaw on natural soils only. 4.2 It is the user's responsibility when using this test method to determine the appropriate water content of the laboratory-compacted specimens (that is, dry, wet, or at optimum water content) ( Note 2 ). Note 2: It is common practice to construct clay liners and covers at optimum or greater than optimum water content. Specimens compacted dry of optimum water content typically do not contain larger pore sizes as a result of freeze-thaw because the effects of freeze-thaw are minimized by the lack of water in the sample. Therefore, the effect of freeze-thaw on the hydraulic conductivity is minimal, or the hydraulic conductivity may increase slightly. 3 4.3 The requestor must provide information regarding the effective stresses to be applied during testing, especially for determining the final hydraulic conductivity. Using high effective stresses (that is, 35 kPa [5 psi] as allowed by Test Method D5084 ) can decrease an already increased hydraulic conductivity resulting in lower final hydraulic conductivity values. The long-term effect of freeze-thaw on the hydraulic conductivity of compacted soils is unknown. The increased hydraulic conductivity caused by freeze-thaw may be temporary. For example, the overburden pressure imparted by the waste placed on a soil liner in a landfill after being subjected to freeze-thaw may reduce the size of the cracks and pores that cause the increase in hydraulic conductivity. It is not known if the pressure would overcome the macroscopically increased hydraulic conductivity sufficiently to return the soil to its original hydraulic conductivity (prior to freeze-thaw). For cases such as landfill covers, where the overburden pressure is low, the increase in hydraulic conductivity due to freeze-thaw will likely be permanent. Thus, the requestor must take the application of the test method into account when establishing the effective stress. 4.4 The specimen(s) shall be frozen to −15°C [5°F] unless the requestor specifically dictates otherwise. It has been documented by Othman, et al 3 that the initial (that is, 0 to −15°C [32°F to 5°F]) freezing condition causes the most significant effects in hydraulic conductivity. Freezing rate and ultimate temperature should mimic the field conditions. It has been shown that superfreezing (that is, freezing the specimen at very cold temperatures and very short time periods) produces erroneous results. 4.5 The thawed specimen temperature and thaw rate shall mimic field conditions. Thawing specimens in an oven (that is, overheating) will produce erroneous results. 4.6 According to Othman, et al 3 the effects of freeze-thaw usually occur by Cycle 10, thus it is recommended that at least 10 freeze-thaw cycles shall be performed to ensure that the full effects of freeze-thaw are measured. If the hydraulic conductivity values are still increasing after 10 freeze-thaw cycles, the test method shall be continued (that is, more freeze-thaw cycles shall be performed). 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/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.