Numerical Modeling of Slope Stability Consideration of an Open-Pit Coalmine in the Phulbari Coal Basin, NW Bangladesh

 

Dr. Md. Rafiqul Islam1* and Mohammed Omar Faruque2

1: Department of Petroleum & Mining Engineering
Shahjalal University of Science & Technology, Sylhet 3114, Bangladesh
2: Department of Petroleum & Mining Engineering
Shahjalal University of Science & Technology, Sylhet 3114, Bangladesh
* Corresponding author

 

 ABSTRACT

The present study deals with a regional-scale two-dimensional finite element method (FEM) numerical model that was developed by using Phase2 software package to delineate the rock strength factor and tension zones in the vicinity of overall pit slope. Mining-induced stresses rate associated with groundwater flow of a proposed large open-pit coalmine that is situated in high-permeability sedimentary deposit have also been evaluated. The modeling result indicates that groundwater from a larger area discharges into the pit with a flow rate of about 5.544m3 per hour through a unit prism of aquifer. The deterioration of rock strength under the influence of groundwater was caused by seepage flow. Large-scale deformation associated with tension zones along the entire pit slope was influenced by the reduction in cohesion of saturated rocks of the coal deposit. Modeling results reveal that there is a high prospect to cause water flow into the tension zones that ultimately would create slope instability. Slope depressurization and drainage programs should set up as needed to maintain safe, stable slopes. However, open-pit coalmine in northwest Bangladesh would really be a great challenge because of high rate of groundwater flow, which is 5.544m3/ hour per unit prism of aquifer, through pit slope.

Keywords: Open-pit coal-mine, slope stability, strength factor, groundwater flow rate

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