ABSTRACT
The choice of tunnel boring machine is a topic of much interest due to the numerous geotechnical challenges posed. The Deccan traps formed are necessarily due to politic and spilitic depositions leading to lava flow horizons. The lava flows cooled and deposited determine the extent of such conditions. The soil investigation report presents the details of the engineering properties anticipated during the tunnel construction. However, geotechnical engineers face tremendous challenge in estimation of seepage pressure due to ground water table, aquifer pressure and proximity to the water bodies or extreme precipitation conditions. The seepage mitigation measures adopted is presented for water supply tunnel at a depth of 100 m. The analysis of the tunnel through the geological mapping, applicable support measures, the stress deformation analysis and lining considerations are discussed. The paper presents these details for a 10 km long tunnel drilled in Mumbai for a water supply project.
