Stability Analysis of Rock and Effect Evaluation of Supporting Scheme in Tianchi Underground Plant

With the implementation of Western Development, West-to-East Electricity Transmission Project and South-to-North Water Diversion Project, a large number of hydro-power stations have been built in the west middleland regions of China. Because of the complexity of terrain, geological and physical-mechanical conditions, the stability of large underground structures becomes one of the most important problems during the engineering design, construction and operation. This paper will take Tianchi hydro-power station as an example, according to the measured stresses at several points, the in-situ stress field is feedback analyzed by using the combination of the genetic algorithm and 3D finite element method. Then, the rheological model of bolted joint rock and nonlinear finite element method are adopted to calculate the displacement field, stress field and D-P point safety factor of the underground structure. The stability of the underground structure is discussed, the excavating and supporting scheme are also presented, and the supporting effect is evaluated. The achievements in this paper can not only be taken as the reference to the design, but also provide some design experiences for other underground structures.