Excavation and optimization theory for giant underground multiple openings in high dipping laminar strata

Abstract

Heterogeneous materials such as polycrystalline rocks and concrete contain a large number of pores and micro-cracks. These micro defects are responsible for the inelastic mechanical behaviour and they finally leads to macroscopic failure under compression and shear. Construction sequences and support parameters have high influence on stability of giant underground caverns. For stability analysis of rock engineering, the most important thing is to simulate macroscopic failure and damage zone of fractures in rock mass due to excavation. Recent research achievements help us understanding the damage and failure processes in brittle rock masses during excavations. Based on damage coupled 3D FEM and fundamental principles of dynamic construction mechanics, numerical simulations have been done to obtain optimal construction sequences for caverns constructed in high dipping laminar strata of Longtan hydropower station, China. The optimal construction sequences of the caverns are obtained by comparison the damaged volumes (Table 1) of surrounding rock mass and displacements of key points. Fig. 1 shows the damage zone of excavation scheme 3 of profile HLO + 51.25. The damage evolution volumes of various schemes formed after the final excavation step are shown in Table 1. The numerical model and conclusions from the research work are useful for analogic rock engineering. (A) Reprinted with permission from Elsevier. For the covering abstract see ITRD E124500.