Abstract

The study of blast effect on bench stability is indispensable, because the overall stability of the quarry’s slope is directly linked to it. For this purpose, a study is conducted in a limestone quarry. Before the stability analysis, a fragmentation evaluation is carried out by two methods, by the Kuz-Ram model and the Digital Image analysis method using the WipFrag program, this part of the work aims to establish a more efficient blast design that assures a better fragmentation and a higher stability for the quarry’s structure. Afterwards, a numerical stability analysis approach is adopted, by employing the Finite Element Method (FEM) through the Phase2 software. A 2D numerical model of the quarry’s profile is constructed, on which simulations are carried out for two cases: 1- static conditions; 2- Dynamic conditions using the proposed blast design. This analysis goals are to define the possible deformation that the blasting process could engender to the benches and its effect on bench’s stability as an individual case and on the overall stability of the slope in general.

Introduction

Drilling and blasting is a preferred method of rock excavation world-wide due to low initial investment, cheap explosive energy, easy acceptability among the blasting engineers and, possibility to deal with different shapes and sizes of openings. Although, drill and blast method has witnessed significant technological advancements, it has inherent disadvantage of deteriorating surrounding rock mass due to development of network of fine cracks in it leading to safety and stability problems [1]. Blasting is usually required to produce easily excavated broken rock, while leaving surrounding rock masses as undamaged and stable as possible [2]. However, it is a well-known fact, that, presently only a meagre percentage of total explosive energy is being utilised in fragmenting and displacing the rock mass [3].

Bench stability dictates overall slope stability and affects utilization of haul road above and below it [4]. Risk of failure is directly related to the stability of a bench, and this in turn is related directly to the danger of rock collapse, which could threaten personnel and machinery at the foot of the pit wall or bench [5].

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