Distribution Law of the Deviatoric Stress Field of Circular Tunnel Surrounding Rock in the Complex Stress Field
In order to clarify the problem of deviatoric stress distribution in the surrounding rock of the deep circular pilot tunnel(set in the middle of the bidirectional tunnel),based on rock mechanics and Mohr Coulomb yield criterion,the analytical solutions of surrounding rock deviatoric stress and plastic zone radius in the plane three-directional stress field were deduced.The deviatoric stress distribution law of surrounding rock for different working conditions and the distribution characteristics of the deviator stress at the boundary of surrounding rock plastic zone were studied.Results show that:when the oblique stress field of circular tunnel is 0.5～1.0 times of vertical stress field,with the increase of horizontal azimuth angle α1=α2 of oblique stress field,the deviatoric stress at the top and bottom of tunnel decreases rapidly and the deviatoric stress at the waist increases rapidly within the range of 1.0 times tunnel radius.For the outside range of 1.0 times tunnel radius,the surrounding rock deviatoric stress firstly decreases slightly and then increases gradually with the increase of horizontal azimuth angle.The shaped distribution of surrounding rock plastic zone was significantly affected by its deviatoric stress.When the oblique stress field of middle pilot tunnel α1=α2 is 30°,the shaped distribution of surrounding rock plastic zone is better.which is circular or elliptical.
plane three-directional stress fieldsurrounding rock deviatoric stresstheoretical analysisplastic zone distribution characteristics
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