Simulation of drainage hole arrays and seepage control analysis of the Qingyuan Pumped Storage Power Station in China: a case study

The Qingyuan Pumped Storage Power Station is located in Liaoning, China and has large-scale water conveyance and underground powerhouse systems. In order to analyze the evolution of the flow rate, external water pressure, and hydraulic gradient of water conveyance and powerhouse systems or around them, a 3D equivalent continuum seepage finite element simulation model was established based on existing theories and a new drainage hole arrays simulation method was proposed in this study. The proposed method had approximate accuracy and was easy to model with fewer nodes and elements in comparison with the substructure method for complex hole arrays of diameter 5 cm. On the basis of four different conditions, the results show that the dehiscence of concrete lining lead to the peak values of the water conveyance flow rate, the water inflow of the powerhouse, and the water discharge of drainage hole arrays. The lapse of drainage hole arrays at a 50% rate resulted in the peak values of the external water pressure around the terminal of the diversion system and the hydraulic gradient around the upstream of drainage hole arrays. Besides, the hydraulic gradient around the downstream drainage hole arrays reached the peak value when the lower reservoir water level rose.