1.1 本标准中描述的试验方法测量了使用嵌入式双向千斤顶组件在双向静态轴向压缩中加载时单个深基础元件的轴向位移。这些方法适用于所有深基础，本文中称为“桩”，其功能类似于打入桩、现浇桩或插入式桩，无论其安装方法如何。测试结果可能无法代表深基础的长期性能。 1.2 本标准规定了在双向静态轴向压缩载荷下测试深基础的最低要求。合格工程师编制的计划、规范和/或规定可提供满足特定测试计划目标所需的额外要求和程序。负责基础设计的工程师（以下简称“工程师”）应批准对本标准要求的任何偏差、删除或添加。 1.3 本标准规定了以下试验程序: 程序A 快速测试 9.2.1 程序B 扩展测试（可选） 9.2.2 1.4 此处指定为“可选”的仪器和程序可能会产生不同的测试结果，并且只有在工程师批准的情况下才能使用。“应”一词表示强制性规定，“应”一词表示建议或咨询性规定。祈使句表示强制性规定。 1.5 工程师可以使用从本标准中的测试程序中获得的结果来预测建造基础中使用的桩的实际性能和充分性。看见 附录X1 有关影响测试结果解释的一些因素的评论。 1.6 合格工程师（专业工程师，不得与上述基础工程师混淆）应设计并批准负载测试配置和测试程序。 本标准的文本引用了提供解释材料的注释和脚注。这些注释和脚注（不包括表和图中的注释和脚注）不应视为本标准的要求。本标准还包括仅供解释或咨询使用的插图和附录。 1.7 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。 1.8 在处理英寸时，使用英寸-磅单位的重力系统- 磅单位。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。 1.9 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 . 1.9.1 本标准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标准的范围。 1.10 本标准提供了有组织的信息收集或一系列选项，并不推荐具体的行动方案。本文件不能取代教育或经验，应与专业判断一起使用。并非本指南的所有方面都适用于所有情况。本ASTM标准不代表或取代必须根据其判断给定专业服务的充分性的谨慎标准，也不应在不考虑项目的许多独特方面的情况下应用本文件。本文件标题中的“标准”一词仅表示该文件已通过ASTM共识程序获得批准。 1.11 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。 1.12 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 双向轴向压缩载荷试验提供了嵌入式千斤顶组件上方移动的桩侧剪力和桩端轴承以及千斤顶组件下方移动的任何侧剪力的单独直接测量。最大移动桩阻力等于千斤顶组件施加的最大荷载的两倍。 测试结果还可以提供用于评估桩沿线侧剪切阻力分布、桩底移动端承量和长期荷载-位移行为的信息。 4.2 规定的最大试验载荷应与工程师预期的试验结果一致。对于永久（工作）桩，作为质量控制或质量保证计划的一部分，工程师可能要求限制施加的测试荷载的大小，以便在预定的验证荷载下测量桩的移动。试图充分调动试验桩轴向抗压强度的试验可使工程师通过减少桩的长度、数量或尺寸来提高桩设计的效率。 4.3 工程师和其他相关方可以分析双向轴向压缩荷载试验的结果，以估计荷载与移动行为的关系，以及在桩顶施加轴向静态压缩或拉伸荷载期间测量的桩承载力（见 注释1- 3. ). 静态试验期间，可能影响桩对轴向静载荷响应的因素包括但不限于: (1) 桩安装设备和程序， (2) 自初始安装以来经过的时间， (3) 桩材料特性和尺寸， (4) 桩附近和下方的类型、密度、强度、分层和地下水条件， (5) 试验程序， (6) 之前的负载循环。 注1: 估算桩的荷载-位移曲线，如同其在顶部受压（如试验方法中一样 D1143/D1143M )，工程师可以使用应变和移动兼容性来计算给定桩顶移动时嵌入千斤顶组件上方和下方的桩承载力。该“顶部荷载”曲线将受到嵌入千斤顶组件上方或下方测得的较小位移的限制。 为了在试验期间获得足够的最小位移，工程师可能希望指定大于所需等效“顶部荷载”的最大试验荷载。 注2: 双向荷载试验在桩内施加试验荷载，导致桩内部应力和桩位移不同于在桩顶部施加荷载试验期间产生的应力和位移。双向测试通常不会测试桩的结构适合性，以支持通常放置在桩顶部的荷载。除非在双向测试之前或之后进行单独的完整性测试，否则可能无法检测到桩顶附近的结构缺陷（见 附注8 ). 分析双向荷载测试结果以估计通过在桩顶部施加压缩荷载测量的桩顶移动，应考虑应变兼容性和荷载- 位移行为。ASTM标准 D1143/D1143M 提供了一种标准测试方法，用于在桩顶施加轴向静态压缩载荷期间直接测量桩顶移动。 注3: 分析双向荷载测试结果以估计通过在桩顶部施加拉伸（提升）荷载测量的桩位移，应考虑应变和移动兼容性。本标准的用户应谨慎解释从压缩载荷分析中估计的抗拉能力。ASTM标准 D3689/D3689M 提供了一种直接测量轴向静态拉伸能力的标准试验方法。 4.4 为了充分发挥轴向压缩能力，工程师通常将千斤顶组件定位在桩内的某个位置，其中组件上方的承载力等于组件下方的承载力。 选择不当的组件位置可能会导致千斤顶组件上方或下方的过度移动，从而限制施加的负载并降低测试结果的有用性。确定组件位置需要适当的现场特征、考虑施工方法以及正确应用工程原理和判断（见 附注4 ). 更复杂的测试配置，使用多级千斤顶组件，可以提供更高的概率来确定桩沿其整个长度的全阻力。有关此类复杂安排的详细信息超出了本标准的范围。 注4: 双向荷载试验可能无法充分调动桩所有截面的轴向抗压桩阻力。考虑到实用性、经济性或规范性，也可能会导致双向负载测试，其目的不是完全调动桩的某些或所有部分的轴向阻力。 在这些情况下，双向测试的解释可能低估了桩的总轴向抗压承载力。 注5: 本试验方法产生的结果质量取决于执行该试验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。本测试方法的用户应注意遵守实践 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 The test methods described in this standard measure the axial displacement of a single, deep foundation element when loaded in bi-directional static axial compression using an embedded bi-directional jack assembly. These methods apply to all deep foundations, referred to herein as “piles,” which function in a manner similar to driven piles, cast in place piles, or barrettes, regardless of their method of installation. The test results may not represent the long-term performance of a deep foundation. 1.2 This standard provides minimum requirements for testing deep foundations under bi-directional static axial compressive load. Plans, specifications, and/or provisions prepared by a qualified engineer may provide additional requirements and procedures as needed to satisfy the objectives of a particular test program. The engineer in charge of the foundation design, referred to herein as the engineer, shall approve any deviations, deletions, or additions to the requirements of this standard. 1.3 This standard provides the following test procedures: Procedure A Quick Test 9.2.1 Procedure B Extended Test (optional) 9.2.2 1.4 Apparatus and procedures herein designated “optional” may produce different test results and may be used only when approved by the engineer. The word “shall” indicates a mandatory provision, and the word “should” indicates a recommended or advisory provision. Imperative sentences indicate mandatory provisions. 1.5 The engineer may use the results obtained from the test procedures in this standard to predict the actual performance and adequacy of piles used in the constructed foundation. See Appendix X1 for comments regarding some of the factors influencing the interpretation of test results. 1.6 A qualified engineer (specialty engineer, not to be confused with the foundation engineer as defined above) shall design and approve the load test configuration and test procedures. The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard. This standard also includes illustrations and appendixes intended only for explanatory or advisory use. 1.7 Units— The values stated in either 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. 1.8 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. 1.9 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026 . 1.9.1 The procedures used to specify how data are collected, recorded and calculated in this standard 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 be commensurate with these considerations. It is beyond the scope of this standard to consider significant digits used in analysis methods for engineering design. 1.10 This standard offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process. 1.11 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. 1.12 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 The bi-directional axial compressive load test provides separate, direct measurements of the pile side shear mobilized above an embedded jack assembly and the pile end bearing plus any side shear mobilized below the jack assembly. The maximum mobilized pile resistance equals two times the maximum load applied by the jack assembly. Test results may also provide information used to assess the distribution of side shear resistance along the pile, the amount of end bearing mobilized at the pile bottom, and the long-term load-displacement behavior. 4.2 The specified maximum test load should be consistent with the engineer’s desired test outcome. For permanent (working) piles, the engineer may require that the magnitude of applied test load be limited in order to measure the pile movement at a predetermined proof load as part of a quality control or quality assurance program. Tests that attempt to fully mobilize the axial compressive resistance of the test pile may allow the engineer to improve the efficiency of the pile design by reducing the piling length, quantity, or size. 4.3 The engineer and other interested parties may analyze the results of a bi-directional axial compressive load test to estimate the load versus movement behavior and the pile capacity that would be measured during axial static compressive or tensile loading applied at the pile top (see Notes 1- 3 ). Factors that may affect the pile response to axial static loading during a static test include, but are not limited to the: (1) pile installation equipment and procedures, (2) elapsed time since initial installation, (3) pile material properties and dimensions, (4) type, density, strength, stratification, and groundwater conditions both adjacent to and beneath the pile, (5) test procedure, (6) prior load cycles. Note 1: To estimate the load displacement curve for the pile as if it were loaded in compression at the top (as in Test Methods D1143/D1143M ), the engineer may use strain and movement compatibility to sum the pile capacity mobilized above and below the embedded jack assembly for a given pile-top movement. This “top-load” curve will be limited by the lesser of the displacement measured above or below the embedded jack assembly. To obtain adequate minimum displacement during the test, the engineer may wish to specify a maximum test load greater than the desired equivalent “top load”. Note 2: A bi-directional load test applies the test load within the pile, resulting in internal pile stresses and pile displacements that differ from those developed during a load test applied at the pile top. Bi-directional testing will generally not test the structural suitability of a pile to support a load as typically placed at the pile top. Structural defects near the pile top may go undetected unless separate integrity tests are performed prior to or after bi-directional testing (see Note 8 ). The analysis of bi-directional load test results to estimate the pile-top movement that would be measured by applying a compressive load at the top of the pile should consider strain compatibility and load-displacement behavior. ASTM D1143/D1143M provides a standard test method for the direct measurement of pile top movement during an axial static compressive load applied at the pile top. Note 3: The analysis of bi-directional load test results to estimate pile displacements that would be measured by applying a tensile (uplift) load at the top of the pile should consider strain and movement compatibility. Users of this standard are cautioned to interpret conservatively the tensile capacity estimated from the analysis of a compressive load. ASTM D3689/D3689M provides a standard test method for the direct measurement of axial static tensile capacity. 4.4 For the purpose of fully mobilizing the axial compressive capacity, the engineer will usually locate the jack assembly at a location within pile where the capacity above the assembly equals the capacity below it. A poorly chosen assembly location may result in excessive movement above or below the jack assembly, limiting the applied load and reducing the usefulness of the test result. Determination of the assembly’s location requires suitable site characterization, consideration of construction methods, and the proper application of engineering principles and judgement (see Note 4 ). More complex test configurations, using multiple levels of jack assemblies, may provide a higher probability that the full resistance of the pile along its entire length may be determined. Details regarding such complex arrangements are beyond the scope of this standard. Note 4: The bi-directional load test may not fully mobilize the axial compressive pile resistance in all sections of the pile. Practical, economical, or code considerations may also result in bi-directional load tests that are not intended to fully mobilize the axial resistance in some or all sections of the pile. In these cases, interpretation of the bi-directional test may under-predict the total axial compressive capacity of the pile. Note 5: The quality of the results produced by this test method are 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 test method 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.