The Application of Geophysical Methods in Identification of Subsurface Fractures in The Vicinity of a Poor Performance Percolation Tank

Percolation tanks are constructed to conserve the rainwater in large quantities and allow more infiltration in its area of influence. Sometimes due to heavy fracture concentration/thick weathered zone, the water in percolation tank migrates fast in short period and tank becomes dry, which leads to early scarcity conditions. The village karkatta of taluka and district Latur is one such village, where water is provided by constructing two wells in the vicinity of percolation tank. The water level in the percolation tank depletes fast and the tank becomes dry in early summer. Also one cement nala bandhara was constructed in the downstream of the nala. The village is funded by UNICEF to implement MUS (Multiple Water Users) project. The area is surveyed by applying both electrical resistivity methods and low frequency electromagnetic methods in submergence of tank as well as in the downstream of percolation tank. The studies reveal that the leakages are due to thick vesicular basalt followed by fractured massive basalt. Suitable remedial measures are recommended to slow down the subsurface flow so as to improve the performance of the percolation tank.

Geoelectrical structure and monitoring in fault zones of Uimon depression in Gorny Altai region using electromagnetic methods

In this paper we present the results of our studies of sections of the Uimon basin in Gorny Altai (Russia) using a complex of electrical prospecting methods. The areas of Baratal Formation at the surface have been investigated. This areas explored in order to understand the stages of formation of the depression. In addition, the possibilities of the electrotomography method for regular observations in seismoactive regions are shown. Comparison of the amplitudes of the resistivity variations based on repeated ERT measurements in different zones of the Terekta fault indicates the activity of its eastern part, which is expressed in significant resistivity variations exceeding 100%. At the same time, the variations in the northwestern part of the fault, reaching 15% on average, are many times smaller.

Electromechanical-Mode Coupling Model and Failure Prediction of CFRP under Three-Point Bending

Carbon fiber reinforced polymer materials (CFRP) cause CFRP to bend or fail when subjected to external loads or impacts. In the case of static three-point bending, using the conductive properties of the carbon fiber inside the CFRP, the overall damage detection and failure prediction can be carried out by electromagnetic methods. The eddy current coil is used to realize real-time monitoring of damage, and the measured voltage value can be mapped to obtain the load of the sample. This paper conducts theoretical analysis and experimental verification, and obtains the relationship between CFRP stress damage and spatial conductivity change, and proposes a CFRP electromechanical coupling model under quasistatic three-point bending. Combined with the theory of electrically ineffective length, the CFRP three-point bending electromechanical coupling model was revised. Experimental results prove that the revised model can describe the load-conductivity change trend of three-dimensional braided CFRP more accurately, which provides a theoretical basis for monitoring the structural health of CFRP through electromagnetic methods.

The application of multi-grounded source transient electromagnetic method in the detections of coal seam goafs in Gansu Province, China

Unknown coal seam goafs will pose various safety hazards in construction and engineering designs, thus the accurate detections of coal seam goafs have become engineering problems that urgently require effective solutions. Multi-grounded source transient electromagnetic methods have the advantages of large detection depths and the easy deployment of emission sources. Therefore, they can be used for explorations in such complex areas as mountains, lakes and swamps. Previously, grounded source transient electromagnetic methods had only one emission source arranged on the surface, and were relatively rarely used in field explorations with multi-grounded sources. This study analyses the electromagnetic response differences between multi-grounded sources and a single-grounded source. The results reveal that the electromagnetic responses of multi-grounded sources were larger. Transient electromagnetic signals were be targeted using combinations of multi-grounded sources, which successfully strengthened the detection abilities. As a result, this study was able to achieve the goals of increasing the detection depths and improving the ability to distinguish geological anomalies. In addition, this research investigation referred to the theory of implicit functions and used the z components of the decay voltage to calculate the apparent resistivity. Finally, the results of the field data of a coal goaf located in Gansu Province, China, showed that the applied multi-grounded sources transient electromagnetic method could obtain higher resolution in coal seam goaf resistivity distribution information.