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Numerical Analysis of the Rock Mass Conditions for Rock Burst Occurrences in Deep Underground Caverns
(1 School of Civil Engineering and Mechanics, Lanzhou University, Lanzhou 730000;2 The Key Laboratory of Mechanics on Disaster and Environment in Western China, the Ministry of Education of PRC, Lanzhou 730000)
Abstract Structural properties of rock masses are the material basis and main factors for rock burst occurrences. In deep tunnels, most rock bursts occur in hard surrounding rock characterized by elasto-friability. Sound conditions for rock masses, such as high strength, fewer original joint fissures and good integrality, are conducive to elastic strain energy accumulation in rock masses. In order to quantitatively analyze the influence of rock mass conditions on the possibility of rock bursts in surrounding rocks, and using the deep tunnel of the Jinping II hydropower station as an example, the uniaxial compressive strength of a rock mass is selected to represent the strength of the surrounding rock and the geological strength index (GSI) is selected to represent the integrality of the surrounding rock mass. With an unchanged surrounding rock geo-stress, different uniaxial compressive strengths and various geological strength indexes, the stress behaviors and ultimate stress state at the stress concentration zones during tunnel construction are calculated by a numerical simulation. The numerical calculation results indicate that intense rock bursts mostly occur in surrounding rock masses of Class II characterized by high strength (uniaxial compressive strength＞120 MPa) and good integrality (geological strength index＞55).
Abstract：
Structural properties of rock masses are the material basis and main factors for rock burst occurrences. In deep tunnels, most rock bursts occur in hard surrounding rock characterized by elasto-friability. Sound conditions for rock masses, such as high strength, fewer original joint fissures and good integrality, are conducive to elastic strain energy accumulation in rock masses. In order to quantitatively analyze the influence of rock mass conditions on the possibility of rock bursts in surrounding rocks, and using the deep tunnel of the Jinping II hydropower station as an example, the uniaxial compressive strength of a rock mass is selected to represent the strength of the surrounding rock and the geological strength index (GSI) is selected to represent the integrality of the surrounding rock mass. With an unchanged surrounding rock geo-stress, different uniaxial compressive strengths and various geological strength indexes, the stress behaviors and ultimate stress state at the stress concentration zones during tunnel construction are calculated by a numerical simulation. The numerical calculation results indicate that intense rock bursts mostly occur in surrounding rock masses of Class II characterized by high strength (uniaxial compressive strength＞120 MPa) and good integrality (geological strength index＞55).
.Numerical Analysis of the Rock Mass Conditions for Rock Burst Occurrences in Deep Underground Caverns[J] MODERN TUNNELLING TECHNOLOGY, 2015,V52(5): 32-39
2015, Vol. 52 