Scholarly record

DETERMINATION OF THE SAFE SLOPE ANGLES IN CHADORMALU IRON MINE OF IRAN USING EXPERIMENTAL, ANALYTICAL AND NUMERICAL METHODS

A. Jafari, J. Gholamnejad

Abstract

Chadormalu Mining and Industrial Company (CMMIC) is mining Chadormalu Iron Ore deposit in Yazd province, central Iran by using conventional open pit mining method. The final pit will be excavated to a depth of approximately 225m with a bottom elevation of 1300m above mean sea level. According to the initial design, the inter-ramp slope angle of 55В° with a 30m bench height, a catch bench width of 10m and 70В° slope angle of individual benches were proposed. Mining to date has intersected complex geology and areas of unfavorable ground conditions; such that the previous mine design parameters of 55В° inter-ramp slope angles may not be achievable in some parts of the pit. This paper presents the results of the investigations carried out for the stability analysis of slopes in Chadormalu Mine which was performed by authors accompany with SRK and Kani Kavan consultants. Geotechnical mapping has conducted to determine and update the geological and structural parameters of in-situ rock mass. Stability analysis has been performed using MRMR classification as a preliminarily design. The analysis was then checked out by using Limit Equilibrium and also Finite Element Methods. According to these analyses, it was found that the major faults, shear zones and deep talus horizons are the major constraints to the slope angles. As a result, the slope angle of 55В° (inter-ramp angle), which had been recommended, are considered to be too steep for the majority of the materials to be exposed in the 30 years pit wall. In this research, with regard to the type of the rock mass, the slope angles ranging from 30В° to 55В° have been proposed. Also in order to keep the slopes safe in some sections, pushing the wall back or pulling it inward was suggested.

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