1.1 目的和应用: 1.1.1 本指南涵盖了使用探地雷达（GPR）方法评估地下材料的设备、现场程序和解释方法。探地雷达最常用于使用高频电磁波（10至7000 MHz）获取地下信息的技术。探地雷达检测电磁特性（介电常数、电导率和磁导率）的变化，在地质环境中，电磁特性是土壤和岩石材料、含水量和体积密度的函数。数据通常使用放置在地面或钻孔中的天线获取。发射天线辐射电磁波，电磁波在地下传播，并从存在电磁特性对比的边界反射。接收探地雷达天线在可选择的时间范围内记录反射波。 如果可以估计或测量地下电磁传播速度，则根据探地雷达数据中的到达时间计算反射界面的深度。 1.1.2 本指南中所述的探地雷达测量用于地质、工程、水文和环境应用。探地雷达方法用于绘制地质条件，包括基岩深度、地下水位深度（Wright等人 ( 1. ) 2. )，陆地和淡水水体下土层的深度和厚度（Beres和Haeni ( 2. ) )，以及基岩中地下空洞和裂缝的位置（Ulriksen） ( 3. ) 还有Imse和Levine ( 4. ) ). 其他应用包括管道、圆桶、储罐、电缆和巨石等物体的位置，绘制垃圾填埋场和沟渠边界图（Benson等人 ( 5. ) )，绘制污染物图（Cosgrave等人 ( 6. ) ; 布鲁斯特和安南 ( 7. ) ; Daniels等人 ( 8. ) )，进行考古（沃恩 ( 9 ) )和法医调查（Davenport等人 ( 10 ) )，检查砖、砌体和混凝土结构、道路和铁路道床研究（Ulriksen） ( 3. ) )，以及公路桥梁冲刷研究（Placzek和Haeni ( 11 ) ). 其他应用和案例研究可以在各种 探地雷达国际会议记录 （Lucius等人 ( 12 ) ; Hannien和Autio， ( 13 ) ，雷德曼， ( 14 ) ; 佐藤， ( 15 ) ; 钻研 ( 16 ) )，各种 地球物理学在工程和环境问题中的应用研讨会论文集 （环境与工程地球物理学会，1988-2019），以及探地雷达研讨会（Pilon） ( 17 ) )，美国环保局( 18 )，丹尼尔斯 ( 19 ) ，和Jol ( 20 ) 提供探地雷达方法概述。 1.2 限制: 1.2.1 本指南概述了探地雷达方法。 它不涉及理论、现场程序或数据解释的细节。为此目的包括参考文献，并被视为本指南的重要组成部分。建议探地雷达方法的用户熟悉本指南中的相关材料以及文中引用的参考文献和指南 D420 , D5730 , D5753 , D6429 和 D6235 . 1.2.2 本指南仅限于从地面进行探地雷达测量的常用方法。该方法可适用于冰上的许多特殊用途（Haeni等人 ( 21 ) ; Wright等人 ( 22 ) )，在钻孔内或钻孔之间（Lane等人 ( 23 ) ; Lane等人 ( 24 ) )，在水上（Haeni ( 25 ) )和机载（Arcone等人 ( 25 ) )应用程序。本指南不包括对探地雷达测量的这些其他适应性的讨论。 1.2.3 本指南中建议的使用探地雷达的方法是最常用、最广泛接受和经过验证的方法； 然而，如果技术上合理且有文件证明，则可以替代技术上合理的其他使用探地雷达的方法或修改。 1.3 单位- 以国际单位制表示的数值应视为标准值。括号中给出的值仅供参考，不被视为标准值。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标准。 1.4 本指南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。 1.5 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。 1.5.1 本标准的用户有责任遵循设备制造商建议中的任何预防措施，并建立适当的健康和安全实践。 1.5.2 如果本标准用于具有危险材料、操作或设备的场所，则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，并确定任何法规的适用性。 1.6 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====== 5.1 概念- 本指南总结了用于解释地质条件、用探地雷达方法识别和提供地质异常和人造物体位置的设备、现场程序和数据处理方法。探地雷达使用高频电磁波（10至3000 MHz）获取地下信息。能量从发射天线向下传播到地面，并从具有不同电磁特性的介质之间的地下边界反射回接收天线。 记录反射信号以产生雷达数据的扫描或跟踪。通常，当天线在地面上移动时获得的扫描并排放置，以产生雷达轮廓。 5.1.1 雷达剖面的垂直比例以双向传播时间为单位，即电磁波向下传播到反射器并返回到表面所需的时间。通过将行程时间与现场测量或关于地下材料中雷达波速度的假设联系起来，可以将行程时间转换为深度。 5.1.2 由于地下电磁特性的变化，传播速度的垂直变化可能导致难以将线性时间尺度应用于雷达剖面（Ulriksen） ( 31 ) ). 5.2 被测参数和代表值: 5.2.1 双向行程时间和速度- 探地雷达轨迹是从具有不同电磁特性的材料之间的界面反射的电磁能量振幅的记录，并记录为两个参数的函数- 双向旅行时间。为了将双向时间转换为深度，需要估计或确定电磁脉冲或波的传播速度。材料的相对介电常数（ε r )电磁脉冲或电磁波的传播方式主要决定了电磁波的传播速度。使用以下关系式近似材料的传播速度（见Balanis中的完整公式 ( 32 ) ): 哪里: c = 自由空间中的传播速度（3.00 × 10 8. 米/秒）， 五、 m = 通过材料的传播速度，以及 ε r = 相对介电常数。 假设磁导率为自由空间的磁导率，损耗角正切远小于1。 5.2.1.1 表1 列出了相对介电常数( ε r )以及各种材料的雷达传播速度。相对介电常数的范围从空气的1到淡水的81。对于非饱和土材料， ε r 范围从3到15。请注意，土壤材料含水量的微小变化会导致相对介电常数的显著变化。对于水饱和土材料， ε r 范围从8到30。这些值具有代表性，但可能随温度、频率、密度、含水量、盐度和其他条件而发生很大变化。 （A） d=密度的函数， w=孔隙度和含水量的函数， f=频率的函数， t=温度的函数 s=盐度的函数，以及 p=压力的函数。 5.2.1.2 如果相对介电常数未知（通常情况下），则可能需要估计速度或使用已知深度的反射器来计算速度。传播速度， 五、 m ，根据以下关系计算: 哪里: D = 反射界面的测量深度，以及 t = 电磁波的双向传播时间。 5.2.1.3 现场速度测量方法见6.7.3。注意，测量的速度可能仅在特定土壤条件下测量的位置有效。如果土壤和岩石成分及含水量存在横向变化，则可能需要在多个位置确定速度。 5.2.2 衰减- 穿透深度主要由电磁能量通过导电、介电弛豫或磁弛豫损耗转换为热能而引起的雷达信号衰减决定。电导率主要由材料的含水量和溶液中自由离子的浓度（盐度）决定。由于地下不均匀性在不需要的方向上散射电磁能量，也会发生衰减。如果不均匀性的尺度与电磁能量的波长相当，则散射可能是显著的（Olhoeft） ( 33 ) ). 影响衰减的其他因素包括土壤类型、温度（Morey ( 34 ) )和粘土矿物学（杜立德 ( 35 ) ). 不利于使用雷达方法的环境包括高导电性土壤、饱和盐水或高导电性液体的沉积物和金属。 5.3 设备- 用于测量地下条件的探地雷达设备通常包括发射器和接收器天线、雷达控制单元以及适当的数据存储和显示设备。 5.3.1 雷达控制单元- 雷达控制单元将信号同步到天线中的发射和接收电子设备。同步信号控制位于天线中的发射器和采样接收器电子设备，以生成反射雷达波的采样波形。这些波形可以被滤波和放大，并与定时信号一起传输到显示和记录设备。 5.3.2 在大多数探地雷达系统中，可以进行实时信号处理以提高信噪比。在有文化噪声的区域和导致信号衰减的材料中工作时，需要时变增益来调整信号幅度，以便在监视器或绘图设备上显示。可以实时使用滤波器来改善信号质量。雷达信号求和（叠加）用于通过提高信噪比来增加有效探测深度。 5.3.3 数据显示- 探地雷达数据显示为单个雷达记录道的连续剖面( 图2 ). 横轴表示水平横向距离，纵轴表示双向行程时间（或深度）。数据通常在摆动轨迹显示中显示，其中接收到的波在瞬间的强度与轨迹的振幅成比例（请参见 图2 )，或作为灰度或彩色显示，其中接收到的波在瞬间的强度与灰度的强度成比例（即，黑色为高强度，白色为低强度；请参阅） 图3 )或根据指定的颜色信号幅度关系定义的某些颜色分配。 5.4.2.4 极化- 矢量电磁场极化的类型和对齐在接收各种散射体的响应时可能很重要。当电场（通常是偶极子天线的长轴）与管道平行对齐并垂直拖曳穿过管道时，两个平行的线性极化电场天线可以最大限度地提高管道等线性散射体的响应。类似地，与混凝土中的钢筋对齐将最大限度地提高绘制钢筋的能力，但与钢筋垂直对齐将最大限度地减少钢筋的散射反射，以穿透或穿过钢筋，从而获得混凝土的厚度。 架空电线和附近围栏也可作类似布置。交叉极化天线（相互垂直）使水平层的响应最小化。 5.4.3 环境、地质和文化条件造成的干扰: 5.4.3.1 通过探地雷达方法获得的测量可能包含由地质和文化因素引起的不需要的信号（噪声）。 5.4.3.2 环境和地质噪声源- 巨砾、动物洞穴、树根或其他不均匀性可能会导致雷达波的不必要反射或散射。电磁特性的横向和垂直变化也可能是噪声源。 5.4.3.3 文化噪声源- 地上文化噪声源包括附近车辆、建筑物、围栏、电线、灯柱和树木的反射。在数据中存在这种干扰的情况下，可以使用屏蔽天线来降低噪声。 (1) 表面或表面附近的废金属可能会对雷达数据造成干扰或振铃。测量线下方或附近的基础、钢筋（钢筋）、电缆、管道、储罐、卷筒和隧道等埋置结构也可能导致不必要的反射（杂乱）。 (2) 在某些情况下，来自附近蜂窝电话、双向无线电、电视以及无线电和微波发射器的电磁传输可能会在雷达记录上产生噪声。 (3) 其他噪声源- 其他噪声源可能由天线与地面的电磁耦合以及由于地形粗糙、植被繁茂、地表水或其他地表条件变化导致的天线与地面的去耦引起。 5.4.3.4 摘要- 应注意调查期间存在的所有可能的噪声源，以便在处理和解释数据时考虑其影响。 5.4.4 替代方法- 前面讨论的限制可能会妨碍探地雷达方法的有效使用，可能需要其他方法或非地球物理方法来解决问题（参见指南） D6429 ). 注1: 应用本标准产生的结果的质量取决于执行工作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 Purpose and Application: 1.1.1 This guide covers the equipment, field procedures, and interpretation methods for the assessment of subsurface materials using the Ground Penetrating Radar (GPR) Method. GPR is most often employed as a technique that uses high-frequency electromagnetic (EM) waves (from 10 to 7000 MHz) to acquire subsurface information. GPR detects changes in EM properties (dielectric permittivity, conductivity, and magnetic permeability), that in a geologic setting, are a function of soil and rock material, water content, and bulk density. Data are normally acquired using antennas placed on the ground surface or in boreholes. The transmitting antenna radiates EM waves that propagate in the subsurface and reflect from boundaries at which there are EM property contrasts. The receiving GPR antenna records the reflected waves over a selectable time range. The depths to the reflecting interfaces are calculated from the arrival times in the GPR data if the EM propagation velocity in the subsurface can be estimated or measured. 1.1.2 GPR measurements as described in this guide are used in geologic, engineering, hydrologic, and environmental applications. The GPR method is used to map geologic conditions that include depth to bedrock, depth to the water table (Wright et al ( 1 ) 2 ), depth and thickness of soil strata on land and under fresh water bodies (Beres and Haeni ( 2 ) ), and the location of subsurface cavities and fractures in bedrock (Ulriksen ( 3 ) and Imse and Levine ( 4 ) ). Other applications include the location of objects such as pipes, drums, tanks, cables, and boulders, mapping landfill and trench boundaries (Benson et al ( 5 ) ), mapping contaminants (Cosgrave et al ( 6 ) ; Brewster and Annan ( 7 ) ; Daniels et al ( 8 ) ), conducting archaeological (Vaughan ( 9 ) ) and forensic investigations (Davenport et al ( 10 ) ), inspection of brick, masonry, and concrete structures, roads and railroad trackbed studies (Ulriksen ( 3 ) ), and highway bridge scour studies (Placzek and Haeni ( 11 ) ). Additional applications and case studies can be found in the various Proceedings of the International Conferences on Ground Penetrating Radar (Lucius et al ( 12 ) ; Hannien and Autio, ( 13 ) , Redman, ( 14 ) ; Sato, ( 15 ) ; Plumb ( 16 ) ), various Proceedings of the Symposium on the Application of Geophysics to Engineering and Environmental Problems (Environmental and Engineering Geophysical Society, 1988–2019), and The Ground Penetrating Radar Workshop (Pilon ( 17 ) ), EPA ( 18 ), Daniels ( 19 ) , and Jol ( 20 ) provide overviews of the GPR method. 1.2 Limitations: 1.2.1 This guide provides an overview of the GPR method. It does not address details of the theory, field procedures, or interpretation of the data. References are included for that purpose and are considered an essential part of this guide. It is recommended that the user of the GPR method be familiar with the relevant material within this guide and the references cited in the text and with Guides D420 , D5730 , D5753 , D6429 , and D6235 . 1.2.2 This guide is limited to the commonly used approach to GPR measurements from the ground surface. The method can be adapted for a number of special uses on ice (Haeni et al ( 21 ) ; Wright et al ( 22 ) ), within or between boreholes (Lane et al ( 23 ) ; Lane et al ( 24 ) ), on water (Haeni ( 25 ) ), and airborne (Arcone et al ( 25 ) ) applications. A discussion of these other adaptations of GPR measurements is not included in this guide. 1.2.3 The approaches suggested in this guide for using GPR are the most commonly used, widely accepted, and proven; however, other approaches or modifications to using GPR that are technically sound may be substituted if technically justified and documented. 1.3 Units— The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information only and are not considered standard. Reporting of test results in units other than SI shall not be regarded as nonconformance with this standard. 1.4 This guide 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. 1.5 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. 1.5.1 It is the responsibility of the user of this standard to follow any precautions in the equipment manufacturer's recommendations and to establish appropriate health and safety practices. 1.5.2 If this standard is used at sites with hazardous materials, operations, or equipment, it is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of any regulations prior to use. 1.6 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 Concepts— This guide summarizes the equipment, field procedures, and data processing methods used to interpret geologic conditions, and to identify and provide locations of geologic anomalies and man-made objects with the GPR method. The GPR uses high-frequency EM waves (from 10 to 3000 MHz) to acquire subsurface information. Energy is propagated downward into the ground from a transmitting antenna and is reflected back to a receiving antenna from subsurface boundaries between media possessing different EM properties. The reflected signals are recorded to produce a scan or trace of radar data. Typically, scans obtained as the antenna(s) are moved over the ground surface are placed side by side to produce a radar profile. 5.1.1 The vertical scale of the radar profile is in units of two-way travel time, the time it takes for an EM wave to travel down to a reflector and back to the surface. The travel time may be converted to depth by relating it to on-site measurements or assumptions about the velocity of the radar waves in the subsurface materials. 5.1.2 Vertical variations in propagation velocity due to changing EM properties of the subsurface can make it difficult to apply a linear time scale to the radar profile (Ulriksen ( 31 ) ). 5.2 Parameter Being Measured and Representative Values: 5.2.1 Two-Way Travel Time and Velocity— A GPR trace is the record of the amplitude of EM energy that has been reflected from interfaces between materials possessing different EM properties and recorded as a function of two-way travel time. To convert two-way times to depths, it is necessary to estimate or determine the propagation velocity of the EM pulses or waves. The relative permittivity of the material (ε r ) through which the EM pulse or wave propagates mostly determines the propagation velocity of the EM wave. The propagation velocity through the material is approximated using the following relationship (see full formula in Balanis ( 32 ) ): where: c = propagation velocity in free space (3.00 × 10 8 m/s), V m = propagation velocity through the material, and ε r = relative permittivity. It is assumed that the magnetic permeability is that of free space and the loss tangent is much less than 1. 5.2.1.1 Table 1 lists the relative permittivities ( ε r ) and radar propagation velocities for various materials. Relative permittivity values range from 1 for air to 81 for fresh water. For unsaturated earth materials, ε r ranges from 3 to 15. Note that a small change in the water content of earth materials results in a significant change in the relative permittivity. For water-saturated earth material, ε r can range from 8 to 30. These values are representative, but may vary considerably with temperature, frequency, density, water content, salinity, and other conditions. (A) d = function of density, w = function of porosity and water content, f = function of frequency, t = function of temperature s = function of salinity, and p = function of pressure. 5.2.1.2 If the relative permittivity is unknown, as is normally the case, it may be necessary to estimate velocity or use a reflector of known depth to calculate the velocity. The propagation velocity, V m , is calculated from the relationship as follows: where: D = measured depth to reflecting interface, and t = two-way travel time of an EM wave. 5.2.1.3 Methods for measuring velocity in the field are found in 6.7.3. Note that measured velocities may only be valid at the location where they are measured under specific soil conditions. If there is lateral variability in soil and rock composition and moisture content, velocity may need to be determined at several locations. 5.2.2 Attenuation— The depth of penetration is determined primarily by the attenuation of the radar signal due to the conversion of EM energy to thermal energy through electrical conduction, dielectric relaxation, or magnetic relaxation losses. Conductivity is primarily governed by the water content of the material and the concentration of free ions in solution (salinity). Attenuation also occurs due to scattering of the EM energy in unwanted directions by inhomogeneities in the subsurface. If the scale of inhomogeneity is comparable to the wavelength of EM energy, scattering may be significant (Olhoeft ( 33 ) ). Other factors that affect attenuation include soil type, temperature (Morey ( 34 ) ), and clay mineralogy (Doolittle ( 35 ) ). Environments not conducive to using the radar method include high conductivity soils, sediments saturated with salt water or highly conductive fluids, and metal. 5.3 Equipment— The GPR equipment utilized for the measurement of subsurface conditions normally consists of a transmitter and receiver antenna, a radar control unit, and suitable data storage and display devices. 5.3.1 Radar Control Unit— The radar control unit synchronizes signals to the transmitting and receiving electronics in the antennas. The synchronizing signals control the transmitter and sampling receiver electronics located in the antenna(s) in order to generate a sampled waveform of the reflected radar waves. These waveforms may be filtered and amplified and are transmitted along with timing signals to the display and recording devices. 5.3.2 Real-time signal processing for improvement of signal-to-noise ratio is available in most GPR systems. When working in areas with cultural noise and in materials causing signal attenuation, time-varying gain is necessary to adjust signal amplitudes for display on monitors or plotting devices. Filters may be used in real time to improve signal quality. The summing of radar signals (stacking) is used to increase effective depth of exploration by improving the signal-to-noise ratio. 5.3.3 Data Display— The GPR data are displayed as a continuous profile of individual radar traces ( Fig. 2 ). The horizontal-axis represents horizontal traverse distance and the vertical-axis is two-way travel time (or depth). Data are commonly presented in wiggle trace display, where the intensity of the received wave at an instant in time is proportional to the amplitude of the trace (see Fig. 2 ), or as a gray scale or color scale display, where the intensity of the received wave at an instant in time is proportional to either the intensity of gray scale (that is, black is high intensity, and white is low intensity; see Fig. 3 ) or to some color assignment defined according to a specified color-signal amplitude relationship. 5.4.2.4 Polarization— The type and alignment of polarization of the vector electromagnetic fields may be important in receiving responses from various scatterers. Two linear, parallel polarized, electric field antennas can maximize the response from linear scatters like pipes when the electric field (typically long axis of the dipole antenna) is aligned parallel with the pipe and towed perpendicular across the pipe. Similarly, alignment with the rebar in concrete will maximize the ability to map the rebar, but alignment perpendicular to the rebar will minimize scattering reflections from the rebar to see through or past the rebar to get the thickness of concrete. Similar arrangement may be made for overhead wires and nearby fences. Cross-polarized antennas (perpendicular to each other) minimize the response from horizontal layers. 5.4.3 Interferences Caused by Ambient, Geologic, and Cultural Conditions: 5.4.3.1 Measurements obtained by the GPR method may contain unwanted signals (noise) caused by geologic and cultural factors. 5.4.3.2 Ambient and Geologic Sources of Noise— Boulders, animal burrows, tree roots, or other inhomogeneities can cause unwanted reflections or scattering of the radar waves. Lateral and vertical variations in EM properties can also be a source of noise. 5.4.3.3 Cultural Sources of Noise— Above-ground cultural sources of noise include reflections from nearby vehicles, buildings, fences, power lines, lampposts, and trees. In cases where this kind of interference is present in the data, a shielded antenna may be used to reduce the noise. (1) Scrap metal at or near the surface can cause interference or ringing in the radar data. The presence of buried structures such as foundations, reinforcement bars (rebar), cables, pipes, tanks, drums, and tunnels under or near the survey line may also cause unwanted reflections (clutter). (2) In some cases, EM transmissions from nearby cellular telephones, two-way radios, television, and radio and microwave transmitters may induce noise on the radar record. (3) Other Sources of Noise— Other sources of noise can be caused by the EM coupling of the antenna with the earth and decoupling of the antenna to the ground due to rough terrain, heavy vegetation, water on the ground surface, or other changes in surface conditions. 5.4.3.4 Summary— All possible sources of noise present during a survey should be noted so that their effects can be considered when processing and interpreting the data. 5.4.4 Alternate Methods— The limitations previously discussed may prohibit the effective use of the GPR method, and other methods or non-geophysical methods may be required to resolve the problem (see Guide D6429 ). Note 1: The quality of the result produced by applying this standard is dependent on the competence of the personnel performing the work, 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.