Numerical Modelling and Field Monitoring of Stability of Cut Slopes

Abstract

The monitoring information is used for variety of crucial functions including safety control, evaluation of current mining plans and future slope design. It provides an active input into mine planning. The early identification of movement zones allows steps to be taken to minimize the impact of mining on stability by the implementation of corrective measures. The main objective of slope monitoring study is to detect any instability well in advance so that any damage to men and machineries can be avoided. If any instability is detected in the early stage then it can be stabilized by applying the suitable remedial measure. The slope materials are inherently weak in the mine. Slope stability monitoring was done in NALCO mine. There were many cut slope areas most of them for the passage of the cable belt conveyor. In order to check the stability of those cut slopes it was proposed the approach of numerical modelling and graphical analysis. The numerical modelling was done in OASYS software and the stability of the sites area checked and factor of safety (FOS) is found in the stable region. On the basis of Numerical Modelling for the geo-mining condition of cut slope surrounding NALCO mine, the factor of safety for the Cut slope I, (near deep cut area), Cut slope II, (near drive house area of height 32m), Cut slope III, (near drive house area of height 24m), and Cut slope IV, (near part II mine area) are respectively 1.335, 1.332, 1.324 and 1.224 with corresponding cut slope height of 20m, 32m, 24m and 35m. Field observation through total station indicated maximum horizontal displacement of 4.3cm, 3.5cm, 4.5cm and -5cm at cut I, II, III and IV respectively indicating stability of slope. Except at few places with local slope failure due to rainfall, all other cut slope are observed to be stable, therefore it is recommended to improve garland drainage and stabilization through geotextile.