Depth Estimates of Buried Utility Systems Using the GPR Method: Studies at the IAG/USP Geophysics Test Site

Abstract

Identifying underground utilities and predicting their depth are fundamental when it comes to civil engineering excavations, for example, to install or repair water, sewer, gas, electric systems and others. The accidental rupture of these systems can lead to unplanned repair costs, delays in completing the service, and risk injury or death of workers. One way to detect underground utilities is using the GPR-Ground Penetrating Radar geophysical method. To estimate depth, the travel time (two-way travel time) information provided by a radargram is used in conjunction with ground wave velocity, which depends on the dielectric constant of materials, where it is usually assumed to be constant for the area under investigation. This procedure provides satisfactory results in most cases. However, wrong depth estimates can result in damage to public utilities, rupturing pipes, cutting lines and so on. These cases occur mainly in areas that have a marked variation of water content and/or soil lithology, thus greater care is required to determine the depth of the targets. The present work demonstrates how the interval velocity of Dix (1955) can be applied in radargram to estimate the depth of underground utilities compared to the conventional technique of constant velocity applied to the same data set. To accomplish this, synthetic and real GPR data were used to verify the applicability of the interval velocity technique and to determine the accuracy of the depth estimates obtained. The studies were carried out at the IAG/USP test site, a controlled environment, where metallic drums are buried in known positions and depths allowing the comparison of real to estimated depths. Numerical studies were also carried out aiming to simulate the real environment with variation of dielectric constant in depth and to validate the results 727with real data. The results showed that the depths of the targets were estimated more accurately by means of the interval velocity technique in contrast to the constant velocity technique, minimizing the risks of accidents during excavation.

Characterization of Antenna Radiation Pattern and Penetration Depth in Ground Penetrating Radar Field Missions

“…The survey was carried out from the Earth's surfa a JSC VNIISMI low-frequency Loza−N DPR [9,26] equipped with a 21 kV pulse tra and antennas with a central frequency of 25 MHz (antenna length of 6 m). Unli frequency 200-400 MHz GPR [36,37] designed for probing the first subsurface me time scale for this measurement was set to 4096 ns (maximum depth of about 200 Similarly to Figure 10, both radar delay time (right scale) and object depth (left s shown in Figure 19b and below, with an estimated "radar velocity" of 5.5 cm/ns. argued with this hypothesis, leaning toward the volcanic origin of the crater.…”

Estimation Diameter of Buried Pipe Using Principle of Ground Penetrating Radar and Electromagnetic Locator

“…In this study, the geophysics method was used to integrate Ground Penetrating Radar and Electromagnetic Locator in order to provide information of buried pipe. Due to the success of geophysical approaches in delivering rapid subsurface information, such as locating buried utilities, forecasting their depth and geometry, geophysical applications in the context of urban planning are becoming more common in the literature (Poluha et al, 2017). Therefore, the integration of geophysics principle of GPR and EML were tested to identify the estimation of diameter of buried pipe.…”

Estimation of different subsurface materials depth using Ground Penetrating Radar

“…Ground Penetrating Radar (GPR) is a geophysical technique that utilize ground penetrating wave which can be used to semi continuously imaging the profile of subsurface material at construction site or developed area. It measured the depth of the submerge object based on the travel time at a specific wavelength [1][2]. GPR is a save electromagnetic wave like other radio wave used for communication or broadcasting [2][3][4].…”

“…It measured the depth of the submerge object based on the travel time at a specific wavelength [1][2]. GPR is a save electromagnetic wave like other radio wave used for communication or broadcasting [2][3][4]. The technique is capable of recording thousands of closely proximity tiny subsurface object at a very fast rate or only a portion of second in a specific time window allocated for capturing reflected wave [5].…”