Numerical Simulation and Performance Assessment of Seepage Control Effect on the Fractured Surrounding Rock of the Wunonglong Underground Powerhouse

Abstract

Seepage control is a key technical problem in large-scale underground cavern engineering, and seepage analysis plays an important role in realizing engineering optimization design and safety. The long-term seepage control effect of a complex seepage control system on the fractured surrounding rock in the Wunonglong underground powerhouse was investigated by using a finite-element numerical model. The permeability of the fractured rock mass was characterized by using a combination of statistical methods and a field water-pressure test. Seepage behavior was modeled in consideration of the complex seepage control system by using the variational inequality formulation of Signorini’s type and the substructure method for dense drainage holes. A global model of equivalent modeling and a submodel of accurate modeling were combined to reduce the difficulty in mesh generation and to balance calculation time with modeling accuracy. The seepage control effect and its sensitivity to the layout of the seepage control system were comprehensively illustrated based on the numerical results. The validity and reliability of the numerical model were verified via in situ measurements. The rationality of the seepage control system for the fractured surrounding rock in the Wunonglong underground powerhouse and its potential for further optimization were discussed.