Depth Analysis for Sensitivity Pattern Section in the Electrical Resistivity using the 2D Computerized Modeling Method

This paper presents the analysis of depth of investigation factors which are (Zm/a) and (Zm/L). The medium depth of investigation (Zm) from the sensitivity pattern of different arrays influences the array selection which is good enough for planning infield surveys. In this paper, the average maximum for data level n value for inline dipole-dipole, pole-dipole and Wenner-Schlumberger for a good subsurface investigation is 6. Then, the spacing of current and potential electrode pair which is a value must be increased. The 2D sensitivity section using the computerized modeling method for each array is able to assist the user in choosing the appropriate array for a practical survey planning after carefully balancing factors such as the cost, investigation depth and resolution. Among the matters for array selection that should be considered are (1) the signal strength, (2) sensitivity of the array to horizontal and vertical changes in the resistivity pattern, (3) investigation depth and (4) horizontal data coverage. Beside than that, the use of appropriate constraint parameters and proper array selection will lead to a better processing and interpretation work in order get reliable and acceptable results. In additional, this paper introduces a new hybrid array called Andy-Bery array. In the application, this new hybrid array is successful and reliable in imaged the conductive block model with it’s actual dimension

Resolution Enhancement in Model Resistivity using the Data Levels Amalgamation Technique for Groundwater Exploration

In the past few years, significant effort has been made in developing field data acquisition in electrical resistivity tomography (ERT) method. This paper presents development of the data level amalgamation (DLA) technique in resistivity data processing. This technique carried out using two different optimized arrays. They are Wenner-Schlumberger and Pole-Dipole arrays. These two arrays is chosen after made full consideration in terms of the signal strength, total number of datum points, sensitivity changes and lastly investigation depth. The real field study for the DLA technique verification was carried out at Taiping, Perak, Malaysia. The objective of field study at this area is related to groundwater exploration. Based on the application of the DLA technique in the field study, it showed that this technique is capable in resolution enhancement in model resistivity with topography results. The DLA technique is useful in increase the technical merit of this geophysical method for Earth’s subsurface imaging

Kartiranje dubine osnovne stijene u granitnom okruženjukombiniranjem metode električne tomografije i bušotinskih podataka

This study used the efficiency of electrical resistivity tomography (ERT) and borehole logs to map the soil-rock interface beneath four traverses (RS1, RS2, RS3, and RS4) in the granitic terrain of Perak, Peninsular Malaysia. The study aimed to evaluate the impacts of the soil-rock characteristic features and interfaces on groundwater and infrastructure development to meet the needs of the increasing inhabitants yearly. The borehole- and ERT-derived lithologic units are strongly correlated. The delineated lithologic units include the topsoil, weathered granitic units (medium stiff to hard silty clay or clayey silt with <800 Ωm), thin to wide-sized weathered/fractured units, and fresh granitic bedrock. These soil-rock profiles and weathered/fractured apertures support sustainable groundwater developments with drill depths above 45 m. In contrast, the delineated clay/silt alternating with stiffer soils, low load-bearing deep-weathered/fractured zones, and bedrock boulders in most places, except beneath traverse RS3, have high affinities for water retention and differential stresses. These features can adversely impact poorly reinforced foundations. Hence, structural elements of the foundations, such as footings or piles, should be placed on stable bedrock, particularly in the central to western parts of the study area. This study has reduced the paucity of information on using ERT and borehole logs for soil-rock interface studies in the study area.U ovoj studiji korišteni su električna tomografija (ERT) i bušotinski podatci za kartiranje dubine osnovne stijene ispod četiri profila (RS1, RS2, RS3 i RS4) u granitnom terenu Peraka, poluotoka Malezije. Cilj studije bio je procijeniti utjecaje karakterističnih značajki dubine osnovne stijene na podzemne vode i razvoj infrastrukture kako bi se zadovoljile potrebe godišnjeg porasta broja stanovnika. Litološke jedinice izvedene iz bušotinskih zapisa i ERT-a snažno su povezane. Određene litološke jedinice uključuju gornji sloj tla, istrošene granitne jedinice (srednje čvrsta do tvrda muljevita glina ili glinasti mulj s < 800 Ωm), tanke do široke istrošene/raspucane jedinice i svježu granitnu podlogu. Ovakvi profili tlo-stijena i istrošeni/raspucani otvori podržavaju održivi razvoj podzemnih voda s dubinama bušenja iznad 45 m. Nasuprot tome, utvrđeni slojevi gline/mulja koji se izmjenjuju s tvrđim tlima, zonama s duboko istrošenim/raspucanim stijenama slabe nosivosti i gromadama osnovne stijene na većini mjesta, osim ispod profila RS3, imaju velike sklonosti za zadržavanje vode i diferencijalna naprezanja. Ove značajke mogu negativno utjecati na loše ojačane temelje. Stoga, konstruktivne elemente temelja, kao što su podnožja ili piloti, treba postaviti na stabilnu stijensku podlogu, posebno u središnjem do zapadnom dijelu istraživanog područja. Ovo je istraživanje smanjilo nedostatak informacija o korištenju metode ERT i bušotinskih podataka u istraživanjima dubine osnovne stijene u razmatranom područj

Enhancement In Resistivity Resolution Based On Data Amalgamation Technique

Kaedah pengimejan kerintangan 2-D menentukan taburan kerintangan pada bawah permukaan Bumi. Peningkatan dalam kualiti data kerintagan 2-D dilakukan menggunakan kaedah penggabungan tahap data (DLA) berdasarkan pertindihan tahap data dengan kombinasi dua susunatur berlainan. The 2-D electrical resistivity imaging measured resistivity distribution at the subsurface. Improvement in 2-D resistivity data quality was carried out by the data levels amalgamation (DLA) technique which is based on overlapping data levels with two different arrays combination

Slope Monitoring Study using Soil Mechanics Properties and 4-D Electrical Resistivity Tomography Methods

In past applications of electrical resistivity survey, users commonly focussed on the Earth's subsurface to locate water table, bedrock, etc. Nowadays, this electrical resistivity method is used by engineers for shallow subsurface investigations. This paper presents the integration of soil mechanics properties with electrical resistivity tomography methods and recommends the proper selection of resistivity array (survey planning) and appropriate inversion constraint parameters (data processing) that are able to deliver optimum resistivity tomography model results. This study identifies the empirical correlations of the soil's properties such as shear strength parameters, moisture content, void ratio, porosity, saturation degree, and Atterberg's limits with the electrical resistivity values (resistivity tomography models). A total of 11 undisturbed clayey sand soil samples was collected at different distances, depths, and times and were tested under both infield and laboratory conditions during the slope monitoring period. The soil mechanics properties of the soil samples were obtained right after the electrical resistivity survey was made. It is shown that the electrical resistivity values are greatly influenced by the soil mechanics properties. Thus, the electrical resistivity (4-D) survey using the optimized Wenner- Schlumberger array (high data density) is capable of reliably enhancing the conventional outcome of the Earth's subsurface investigatio

High Resolution Time-domain Induced Polarization Tomography with Merging Data Levels by Two Different Optimized Arrays for Slope Monitoring Study

High Resolution Time-domain Induced Polarization Tomography with Merging Data Levels by Two Different Optimized Arrays for Slope Monitoring Stud

High Resolution Time-lapse Resistivity Tomography with Merging Data Levels by Two Different Optimized Resistivity Arrays for Slope Monitoring Study

In this paper, we present high resolution time-lapse resistivity tomography study for slope monitoring using two optimized resistivity arrays of Wenner-Schlumberger and pole-dipole. These optimized resistivity arrays of Wenner-Schlumberger and pole-dipole give total of 2038 datum points for each data set. This slope monitoring study was conducted at Minden, Penang Island, Malaysia. Inversion results from computer suggested that optimized Wenner-Schlumberger and pole-dipole arrays would be equally effective but the merge data levels technique for both arrays would able to provide high resolution at imaging slope area. Our in-field data results showed that the two arrays imaged the subsurface for slope monitoring equally well. When in-field data levels from these two different arrays were merged and analyzed using 2-D inversion, however, the merging data levels using two different arrays was able to resolve the subsurface characterizations. Because the merging data levels using two different arrays requires roughly two times as measurement per line, we conclude that this technique is preferable for environmental geophysics than single array only when the high improvement in resolution at sensitivity, horizontal coverage, signal strength and investigation depth is more important than rapid data acquisition. The overall results using these two different arrays were quite compromising and remarkably significant for good improvement in data quality and data acquisition technique

New empirical approach for the estimation of soil cohesion and friction angle in 2D form for site investigations

This paper presents the multiple linear regression (MLR) models developed from electrical resistivity and seismic refraction surveys for quick prediction of subsurface soil’s shear strength parameters. A total of four parameters have been considered with electrical resistivity and seismic refraction velocity as the independent variables: and soil cohesion and internal friction angle as the dependent variables. In order to mitigate the effects of nonlinearity of resistivity and velocity, both datasets were initially log-transformed to conform with the fundamental assumptions of regression analysis. Two models were therefore built based on the strong multiple linear relationships between explanatory and response variables, with coefficient of determination (R2), 0.777, p-values, < 0.050, Durbin-Watson value, 1.787 and multicollinearity, 1.185. The obtained models’ coefficients were transferred and used for the estimation of 2D models soil cohesion and internal angle of friction for validation. Thereafter, the developed models demonstrated good performance, having subjected to accuracy assessment with results at < 5%, and < 10% for the root mean square error (RMSE) and weighted mean absolute percentage error (MAPE) respectively. Therefore, the new developed soil’s shear strength MLR models have provided continual description of soil properties in two-dimensional form, enhancing the subsurface information for site investigations as compared, to one-dimensional information from the invasive method

Enhancement in resistivity resolution based on the data sets amalgamation technique at Bukit Bunuh, Perak, Malaysia

In this paper, we have carried out a study with the main objective to enhance the resolution of the electrical resistivity inversion model by introducing the data sets amalgamation technique to be used in the data processing stage. Based on the model resistivity with topography results, the data sets amalgamation technique for pole-dipole and wenner-schlumberger arrays are successful in identifying the boundary or interface of the overburden and weathered granite. Although the electrical resistivity method is well known, the proper selection of an array and appropriate inversion parameters setting such as damping factors are important in order to achieve the study objective and to image the target at the Earth’s subsurface characterizations