Groundwater Pathway Mapping Using Electrical Resistivity Tomography (ERT) Method

Geophysical electrical resistivity method has been one of the more popular non-destructive method to explore the subsurface. Geophysical electrical resistivity tomography (ERT) subsurface profiling was conducted to map the groundwater path along the embankment. The groundwater path able to decrease the slope stability, thus its need to locate the position for conduct the slope remediation via subsoil drainage. In this study, Terrameter LS2 model, electrodes, cables, battery, and cable connectors were the equipment used for measurement. This study uses cable spread line at 200m with 2.5m spacing between electrodes by using gradient protocol. The resistivity data was analyzed using RES2DINV software. The interpretation of groundwater path is based on the resistivity values less than 100 ohm.m, which is interpreted as saturated materials. This study demonstrates the efficiency of application of electrical resistivity tomography (ERT) in detecting the groundwater pathways. This investigation will help in sustaining the slope stability via indicating the position of groundwater pathways, and thus implementing the slope remediation work.

Electrical Resistivity Tomography Application for Buried Foundation Investigations: Insights and Review

Maintenance of existing structures and development or reuse of brownfield sites need to determine buried foundations, in terms of location and dimensions, as accurately as possible. Geophysical methods provide an indirect way to look in the ground and provide information about the subsurface that the traditional methods might be unable to. In particular, the electrical resistivity method has been performed in the context of buried foundation surveys. This review spots the light on the main results obtained from utilizing the electrical resistivity method and the most affecting parameters that can influence the obtained resistivity models, and also, focuses on published case studies to merge their findings to understand the interaction among the method, the foundation and the hosting background for buried foundations surveys. The case studies mentioned in this review show the resistivity method's success and highlight the most important parameters that can control the method’s applicability and data interpretation. The integration of the geophysical-traditional methods has appreciable potential for more accurate findings.

2D electrical resistivity imaging to determine depth of andesite spreading at Tanjung Batu, Jambi as eco-friendly exploration of minerals method

Tanjung Batu has potential subsurface minerals in the form of Andesite rocks. Andesite can be used appropriately for infrastructure with excellent physical features, including hardness, compressive strength, density, as well as the water and weather resistance level. Andesite is one type of igneous rock that is widely used in the construction sector, especially infrastructure such as roads, bridges, housing, airports, and seaports. In mining, the depth of mineral exploration usually using borehole method. In this study used electrical resistivity method with dipole-dipole configurations. Electrical resistivity is also capable for identifying Andesite rocks in subsurface without drilling the area because each rock has a different rock resistivity value. In this study used 240 meters of track and 20 meters space of electrodes. Based on 2D Imaging, range of Andesite resistivity in this area was 170 - >1095 Ωm. Andesite depth was at 3.42, 10.6, 18.5 and - 27.2 m.

Applications of Geophysical Methods in Tunnel and Oil Exploration

Geophysical studies can be utilized adequately to decide the land, hydro geographical and geotechnical properties of the ground mass in which the designing development is occurring. The investigation must be given to the contractor to ensure the information related to soil or to predict the type of equipment to be used and to estimate productivity and cost. This article examined how integrated geophysical methods were carried out for the determination of the degree of fracturing and rigidity of rock mass. Data were collected from different case studies in which comparison is there between different types of methods suited for different type of evaluations. In this paper, methods involved for the explorations are seismic refraction method, electrical resistivity method, magnetic and gravity method for oil explorations. The authors found that gravity and magnetic are best suited methods for the oil sand exploration and because of the high acceptance of designing a lot latest applications expected in future. The techniques used in these methods are relatively cheap and fast finding in comparison to other methods.

Contribution of Geo-electrical Soundings and Pedological Wells to the Estimation of the Tonnage of Laterite Gravels of the Northwestern Flank of Mount Bangou: Implication in Road Construction.

The increasing demands on lateritic gravels in road construction nowadays make it necessary to quantify the available resources that can be used in road construction. The aim of this study is to estimate the tonnage and to valorize the lateritic gravels of the North flank of Mount Bangou (West, Cameroon) in road construction. Interpretation of 48 vertical electrical soundings coupled with 20 pedological wells from 05 lateritic gravel sites was carried out to determine the thickness of the gravelly horizon. The thickness of the gravelly horizon obtained from the geo-electrical soundings is the highest (8.88 to 12.45 m) compared to that obtained from the pedological wells (1.23 to 1.98 m) and thus shows the inadequacy of the pedological wells for the determination of the thickness of the lateritic gravels. Thus, the electrical resistivity method is appropriate to estimate the thickness of the gravelly horizon. The lateritic gravels studied are characterized by the electrical resistivity curves of type K, HK, Q, QH, KQ, HKH, H and KH. The medium (8 to 36 m) and thick (13 to 44 m) zones are areas of high potential lateritic gravels. The proven reserves of lateritic gravels at the Chenye, Sekakouo, Bamendjou 1, Bamendjou 2 and Bangam sites are respectively 3479 003 t, 1 389 522 t, 5 002 505 t, 839 455 t and 2 663 105 t and can build respectively 539 298 m; 226 167 m; 131574 m; 778314 m and 401068 m of road, either as a form layer or sub-base.

Geophysical and Geotechnical Investigation of Building Failure in A Typical Basement Complex Environment – A Case Study in Ile-Ife, Nigeria

A building located within the Basement Complex of the ancient town of Ile – Ife, Osun State, Southwestern Nigeria was observed to have failed due to excessive total and differential settlement. The failure was investigated using the electrical resistivity and geotechnical methods The electrical resistivity method involved the 2-D electrical resistivity imaging (ERI) technique using the dipole-dipole array along four traverses of 30 – 60 m in lengths. The geotechnical method involved the cone penetration test (CPT) using the 2.5-ton static penetrometer machine. Quantitative and qualitative analysis of the ERI data were made using the DIPROfWIN software for the pseudo-inversion while the CPT data were interpreted for lithology using standard chart. The results show that the topsoil, about 1.0 m thick, is composed of sandy clay/clay that is characterized by cone resistance (qc) of 0.2 – 2.0 MPa and resistivity of 75 - 200 Ωmm. The underlying clayey weathered layer, which constitute the shallow foundation soil is characterized by thickness of 4 - >10 m, qc of 0.2 – 1.0 MPa, resistivity of 25 - 75 Ωmm and estimated consolidation settlement of 200 – 500 mm. The basal layer is the saprock/fresh bedrock characterized by qc of > 8.0 MPa and resistivity of 100 - 1000 Ωmm. The subsoil is thus characterized by variably thick incompetent clayey weathered layer within which the shallow foundation was placed; hence the excessive total and differential settlements.

4D investigation of water infiltration in waste dumps using electrical resistivity (Elatsite mine, Bulgaria)

The objective was to investigate how water infiltrated into waste dumps at a mine site. The electrical resistivity method of field geophysics was applied to produce 4D imaging of progressive water infiltration into the waste dump. The goal is to test a method for investigating how rain water infiltrates unconsolidated materials in mine waste dumps. This is an important problem when evaluating the water balance in waste dumps and understanding the conditions for contamination of the water flowing through the waste materials. The trial was carried out in one of the two large dumps at Elatsite mine, which are composed of rocks with various fragment size and diverse mineral composition. The investigation was undertaken by discharging salt solution into the waste dump and taking geophysical measurements on a rectangular electrode grid at certain time intervals. The grid consisted of 64 electrodes forming 10×5 m cells and covering a 70×35 m area. As a result, it was possible to record how the infiltration and dispersion of the salt solution developed in space and time. In the last one of the seven surveys, 40 hours after the start of the trial, it was established that the salt solution reached a depth of approximately 40 m. The results could be used for predicting the interaction between water and waste material.