Recent advances in excavation, design and support methods: A case study of Mangdechhu project, Bhutan

摘要

Construction of hydro power projects in the Himalayan region poses various problems which can have direct implication on the cost and time schedule of the projects. Varying geological conditions necessitate use of modern methodologies for ensuring stability and overall time bound completion of the project. The 720 MW Mangdechhu HE project being undertaken by the MHPA in the Himalayas in the northern parts of Bhutan, is one such project. Here the project authorities have addressed the adverse geological conditions by adopting various technologies for achieving scheduled completion of the project while ensuring stringent quality norms and minimal cost overrun. The Project has encountered adverse geological conditions during excavation of the various appurtenant structures. The stability of the structures has been studied in detail by the aid of numerical modeling, and support measures evaluated. Accordingly, best engineering techniques have been adopted to ensure long term safety of the structures. This paper exclusively deals with these recent rock engineering solutions such as pre-excavation grouting, diaphragm wall etc. for overcoming construction related problems while ensuring quality norms and also maintaining the construction schedule dates for commissioning of the project by March 2018.