A proposal for optimizing the tunnel design of the Khalashpir coal field, Bangladesh

The Khalashpir coal field is one of the five hitherto discovered coal fields in Bangladesh. The 25 sq km coal field accommodates itself to the prolific northwestern part - deemed as the Stable Precambrian Platform - of the country representing a Gondwana deposit. The total in-situ reserve of coal in 8 seams of the 7.5 square km surveyed area is 451 million tons while the measured reserve is 277 million tons and the indicated reserve is 174 million tons. However, only seams I, II and IV are considered to have potential for mining. Our aim is to provide a tool - to design a tunnel for the coal field - to be used throughout the planning and construction process. We know a strong bond ties the Murphy's Law and the science of Geology together. Tracking the variability of geologic conditions is thus a real challenge in the optimization of the tunnel design. Consequently, recording of the geological parameters along the excavated tunnel has to be made as the tunnel construction proceeds. A case study has been done in order to develop insight into the loading mechanisms and nature of the associated convergence in the long wall mining. A series of nonlinear equations on the concrete support structure has also been analyzed with the finite element model developed. We make use of the Finite Element Method (FEM) to produce a reliable and practical tunnel design.; Tunnel cross section ; Coarse finite element mesh using the quadrilateral elements. Node numbers are as shown - 33 elements.