Junaid, Muhammad; Abdullah, Rini Asnida; Ullah, Arshad; Sa’ari, Radzuan; Mahmood, Sajid; Rehman, Hafeezur; Rehman, Safi ur; Sari, Mahmut

An expeditious and precise slope stability assessment approach is required to mitigate the personnel and economic losses due slope failure disaster. This study successfully determines various discontinuity properties such as degree of fracturing, discontinuities orientation and persistence using combine unmanned aerial vehicle (UAV) and 2D electrical resistivity tomography (2D ERT) to evaluate the stability of the slope. The discontinuity orientations govern the various modes of failure such as planar, wedge, and flexure toppling. Whereas the degree of fracturing of the rock mass evaluates the quality of the rock mass using Rock Quality Designation (RQD) index. In addition, the persistence is defined as the extent to which the discontinuity on exposed surface rock intruded inside the rock mass. The 3D point cloud from UAV images allows to obtain the discontinuity orientations to analyse the potential failure at the site. The upper portion of the slope has no risk of planar and wedge failure, whereas 20% of the discontinuities are favourable for flexure toppling. In contrast, at the lower section of the slope 1.04%, 4.86% and 20% discontinuities are prone to planar, wedge and flexure failure respectively. At the same time the RQD index obtained via UAV survey reveals that the respectively area covered by very poor, poor, fair, good, and excellent rock were 7 m2, 3904 m2, 38,775 m2, 42,943 m2, 1546 m2. The ERT survey enable to estimate the area covered by poor, fair, good and excellent rock were 4 m2, 1650 m2, 2592 m2, 27,729 m2, and 55,200 m2, respectively. Both the UAV and 2D ERT survey shows the poor-quality rock in the north-east of the slope that reveals that the discontinuities are extended inside the rock mas. This study, therefore, conclude that the combined 2D ERT and UAV approach is efficient and expeditious approach for comprehensive slope stability assessment.

Junaid, Muhammad; Abdullah, Rini Asnida; Ullah, Arshad; Sa'ari, Radzuan; Mahmood, Sajid; Rehman, Hafeezur; Rehman, Safi ur; Sari, Mahmut

In this article the author’s name Mahmut Sari was incorrectly written as Mahmut Saari. The original article has been corrected.

Junaid, Muhammad; Abdullah, Rini Asnida; Sa’ari, Radzuan; Ali, Wahid; Islam, Amber; Sari, Mahmut

This research work aims to critically analyze the efficacy of inexpensive and rapid 2D electrical resistivity tomography (2D ERT) survey for sub-surface geological delineation of granite deposits. The research work involves six ERT profiles using the Schlumberger protocol with an inner and outer electrode spacing of 5 m and 10 m, respectively. In addition, the unmanned aerial vehicle (UAV) survey is also performed to obtain the terrain information of the studied area. At the same time, a few boreholes are drilled to validate the 2D ERT interpretations. The 2D ERT survey reveals that strong resistivity contrast enables inverted resistivity imaging to characterize the deposit such as topsoil (100-800 Ωm), fracture granite (800-2300 Ωm), and solid granite (> 2300 Ωm). The results obtained from UAV, 2DERT, and borehole survey are further processed to estimate the bedrock to topsoil ratio to assess the feasibility of the deposit. The bedrock to topsoil ratio, estimated by 2D ERT and borehole, is 3.2 and 2.2, respectively. At the same time, the combined UAV, 2D ERT, and borehole survey calculates the bedrock volume 3.2 times to topsoil. Thus the research work allows us to conclude that 2D ERT is an inexpensive, viable, and efficient technique for sub-surface geological documentation, and helps select appropriate mining methods.