ANALYTICAL SOLUTIONS OF CIRCULAR TUNNEL UNDER TWO-DIMENSION UNEQUAL PRESSURE CONSIDERING DILATANCY AND SOFTENING
BIAN Kang1,XIAO Ming2
(1. State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,
Chinese Academy of Sciences,Wuhan,Hubei 430071,China;2. State Key Laboratory of Water Resources and
Hydropower Engineering Science,Wuhan University,Wuhan,Hubei 430072,China)
Abstract:Base on the elastoplastic softening model and non-associated flow rule,the lateral pressure coefficient,the included angle with the polar axis and principal stress corresponding relations under different engineering conditions are considered. Combine with the strain softening and dilatancy characteristic of rock after it comes into the yield stage,the analytical solutions of elastoplastic stress,displacement and plastic radius of the circular tunnel are deduced. The result of computation example shows that the lateral pressure coefficient and principal stress corresponding relations decide the distributing shape of plastic zone nearby the tunnel. Dilatancy has a much more important influence on the rock displacement nearby the tunnel than on the plastic radius. The influence of dilatancy extent to the deformation nearby the tunnel becomes larger when the strain softening characteristic of surrounding rock increases. In the project which is controlled by the displacement nearby the tunnel,the influence of strain softening and dilatancy can not be ignored.
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