Drainage System Optimization of Powerhouse Foundation Pit in Construction Period for Jinnah Hydropower Project

The powerhouse of Jinnah Hydropower Station on Indus River in Pakistan is sitting on a deep overburden layer with maximum depth of 200m. A three- dimensional (3-D) finite element model of seepage flow is set up, which can represent the project geological structure and the geometry boundary of the powerhouse foundation. The influence of different layout schemes to seepage filed of foundation is analyzed and compared in detail, such as setting up the high pressure jet grouting cut-off wall (HPJGCW) and its depth, different number and space between drainage wells etc. An optimizing drainage system of powerhouse foundation pit during the construction stage is put forward. The optimizing drainage system is Scheme 3, which is drainage ditches on ground surface with outer round of HPJGCW and drainage ditches of foundation pit.