The VLF-EM imaging of potential collapse on the LUSI embankment

Arabian Journal of Geosciences

Electrical resistivity imaging is a widely used tool in near surface geophysical surveys for investigation of various geological, environmental and engineering problems including landslide. In this study, an electrical resistivity tomography (ERT) survey was conducted in a landslide area, located in the So¨ke district of Aydın, Turkey. In 2003, the Neogene-aged units on the slope next to a newly built school building became unstable due to an excavation work and moved after a heavy rainfall. The resulting landslide partly covered the school. The authors carried out a 2-D resistivity survey along three profiles over the landslide mass using a Wenner configuration. It yielded useful infor-

Materials and Geoenvironment

Geophysical investigations involving very low frequency electromagnetic (VLF-EM) and vertical electrical sounding (VES) techniques were deployed to study the pavement failure along a major road in a typical basement complex terrain of southwestern Nigeria. This study was designed to assess the failure and provide a basis for ultimate engineering design. The study delineated a 3- to 4-layer geoelectric sequence: a topsoil of thickness varying from 0.4 to 1.2 m, a spectrum of clayey materials of thickness varying from 1.9 to 14.5 m and a weathered/fractured basement occurring at depths of between 3.6 and 15.0 m. The shallow basement indicated low bearing capacity, with resistivity values ranging from 62.1 to 377.9 Ωm. The presence of clay/clayey materials, linear features and the effect of rising water table within the influence zone underlined the pavement failure. This information will facilitate appropriate designing, soil improvements and selection of materials for road constructi...

Geology, Geophysics and Environment, 2016

A series of catastrophic floods that have occurred over the last twenty years in Poland, brought an urgent need for taking preventive steps to monitor river embankments conditions. The main problem seems to be development of efficient, ie. fast and economical measurements for controlling the condition of the river embankments, because the execution of the full range of geotechnical measurements is lengthy and costly. In this situation, thecheap and quick geophysical survey has been proposed to undertake this purpose. In this article the results of geophysical surveys were described which were performed using geoelectric and electromagnetic methods along a section of the Vistula embankment, located near the Maniow area in the Malopolska province. According to the archival data, this region is situated at the high-risk flooding zone. Three geophysical methods were used to recognize geotechnical conditions of the levee: (i) Electrical Resistivity Tomography (ERT), (ii) Induced Polar...

A geophysical investigation to study anomalies and determine the distribution of rocks within the subsurface using the Very Low Frequency Electromagnetic (VLF-EM) method was conducted around Gambar Wetan Temple. We have measured subsurface structure by dividing the area into several tracks. The spacing of trajectory is 1 meter. The measurement was done at each point on each trajectory with spacing of 0.5 meters. As a result, we get the data of inphase, quadrature, t-fields, and tilt. Noise-Assisted Multivariate Empirical Mode Decomposition (NA-MEMD) was applied to the data to denoise the signal of VLF-EM data. The NA-MEMD filtered data were then interpreted qualitatively using Karous-Hjelt filter to get the location of the anomaly which is more conductive or more resistive. Quantitative interpretation using Inv2DVLF-v1 for the inversion of tipper data (inphase and quadrature) were also done to get the apparent resistivity profile. Then, both were combined to get the overall interpretation. The results showed that there are generally two anomalies detected around the temple in 4 lines measurement, conductive and resistive anomaly. The resistive anomalies which are predicted as andesit has a resistivity 120-220 Ωm at depth of 0-40 meters. This is expected to help in finding rocks within the subsurface because the main temple has not been found.

International journal of Geosciences, 2020

Very low frequency (VLF-EM) was used to assess variations in overburden composition, bedrock lithology and the hidden Sedimentary structures within the foundation of Shagari Dam of the sedimentary basin of Northwestern Nigeria. Four VLF-electromagnetic (EM) traverses were occupied at 10 m intervals. The VLF normal and filtered real component irregularities identify major geological interfaces suspected to be faults/fractured zones. The points of crossover between the real and imaginary components delineate the fractured zones, which were identified as areas of possible seepage (sloughing and piping). The fractured zones are suspected to be present at all traverses. In total, 38 fractured zones were identified along the dam embankment and canal site, while 17 major fractures occurrence dippers along the Traverses at a point coincide with cross over point at 4 traverses. These seepage zones cause heterogeneity in the sub-surface structure that could be prime to dam failure which in turn leads to the flooding, decreases in irrigations activities of the peoples leaving around the dam and loss of several hundreds of life when care not taken. The result of the study suggests that VLF is suitable for observing seepages in embankment dams.

Environmental Earth Sciences, 2018

The earth on LUSI embankment has a high failure potential due to several factors such as: seepage, leakage, vertical and horizontal deformation, cracking and fault (discontinuity), overtopping, mud slide, and swelling. Very low frequency electromagnetic method was carried out at LUSI embankment in order to delineate fracture and potential pathway of seepage occurring through the subsurface structure the embankment body. To reach these objectives, several methods were carried out in the selected area, such as direct current resistivity, total station and Rayleigh wave dispersion to provide information on the mechanical properties LUSI embankment subsurface. This study indicates that seepage and fracture through the LUSI embankment is presented by a set of lines which are possibly caused by deformation in the LUSI area. Furthermore, based on the fracture and seepage positions and mud or fluid flow direction, the unstable LUSI embankment is determined as located around the northwest and northern parts of the area.

AIP Conference Proceedings

Gorontalo is one area that is very vulnerable to flooding. Flood problems in Gorontalo must have a solution that can have a positive impact on the community and the government. The purpose of this research is to identification subsurface structure of the Ilotidea Region by using resistivity method. The result of this research will be used for the fundamental of developing the Flood Tourist Science Village. The method that used in this research is to take subsurface data by using the IPMGEO-4200 Electrical Resistivity Meter in 6 points at Ilotidea Village. Processing data through calculating the apparent resistivity (ρa) by entering the values ∆V, I, R and K, then interpreting the subsurface structure of the Ilotidea region. Based on the results of the data analysis, there are obtained 5 layers at each data retrieval point. The layers found at each point are composed of sandy clay, clay, sand, clay, and sandstone. Based on the results of the interpretation of the subsurface structure, the sandy clay layer is arranged with a layer of clay which has the characteristic of not easily escaping the water. This causes the Ilotidea area to be very vulnerable to flooding because when surface runoff and rainfall falls into this area has a high intensity and volume it will cause inundation due to the absence of water absorbed by material found below the surface. Based on the subsurface structure of the Ilotidea region, the house foundation that will be made in a flood tourism science village must reach a depth of 5-10 m where at this depth the layer is a clay layer which is not easy to escape and elastic so the house is not easy to collapse

Journal of Materials Science and Surface Engineering

Throughout Burkina Faso's road network, some roadways have experienced subsidence or collapse following pipe ramming works conducted for the laying of pipes such as drinking water supply networks. When such works are conducted, it is difficult to make a diagnosis of the properties of the formations underlying the road embankment because a destructive sounding would lead to expensive and tedious repairs. In this present study, a geophysical method, namely electrical resistivity tomography has been used to image the structure and the geometry of these formations so as to anticipate potential disasters. Four electrical resistivity profiles were conducted near the insertion and receiving pits, parallel to the national road N°4, at the exit of the capital Ouagadougou. The strategy of prospection has allowed to image down to an investigation depth of approximately 10 m. The study showed that at an average depth of 2 m, an environment of very low electrical resistivity (about 50 ohm.m) is observed in a very resistant environment. This conductive environment corresponds to the presence of a porous and very wet material which extends laterally and in depth under the roadway, and which can lead to a subsidence or a collapse of this roadway on the surface.

Electrical resistivity imaging (ERI) survey was conducted in an area where landslide occurred in the Elmadag district of Ankara-Kirikkale highway and railway route, central Turkey. Landslide occurred after heavy rainfall in a rock consisting of a succession of limestone layer which was fractured. Electrical resistivity and borehole surveys were carried out to obtain the characterization and quantification of the weathered zone. The ERI sections were obtained from the dipole-dipole array. The results allowed mapping of the weathering material at depth and provided information on the depth of the sliding surface. However, the depth of the sliding surface is between 15 and 50 m.