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Abstract Strength reduction theory is introduced into security and stability research of the underground gas storage caverns group，and critical failure criterion of caverns is put forward. In the static analysis，critical failure criterion is transfixion of equivalent plastic strain among caverns. In the long-term rheological analysis，critical failure criterions include transfixion of equivalent plastic strain among caverns and the limiting shrinkage state of caverns? volume. Rock material strength parameters are reduced by reduction factor(F) step by step and the general safety factor of caverns is obtained when the calculated results just reach critical failure criterions. Jintan salt-rock underground gas storage is taken as an example. Numerical model is created by using the software of fast lagrangian analysis of continua in three-dimention(FLAC3D) and the model is analyzed both in static state and long-term rheological state based on strength reduction theory. The general safety factors of caverns are obtained in different conditions. In the static analysis，equivalent plastic strain among caverns develops continually with the increasing of the reduction factor and the general safety factor of caverns is 2.25. In the long-term rheological analysis，the key failure factor of the caverns transforms gradually from volume shrinkage to transfixion of the equivalent plastic strain among caverns. With the same numerical model parameters and internal pressure as the static analysis，the general safety factor of caverns is 1.83 after the system operates for 50 years. The relationships among safety factor，pillar spacing，pressure condition and failure mode are discussed. It is useful for safe operation and stability evaluation to other similar salt-rock underground gas storages group.
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Received: 27 April 2012
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2012, Vol. 31 
