各向异性黏弹性隧道开挖位移时变解析解

Time-varying displacement analytical solution of anisotropic visco-elastic tunnel excavation

针对各向异性初始应力状态(侧压力系数K 0不等于1)的岩体隧道开挖问题,假定开挖岩体为Max-well黏弹性模型,从各向异性条件下围岩位移解答出发,通过对应性原理求解圆形隧道施工开挖过程中的围岩位移时变解,探讨各因素对围岩位移的影响.结果表明:对于隧道顶点,当各向异性参数(侧压力系数)K0>1时,先是向围岩方向产生位移,此后流变作用的影响导致围岩位移逐渐向隧道内转变;而对于K 0≤1,隧道一旦开始开挖,随即向隧道内产生围岩位移,且时变位移随K 0的不断减小而逐渐增大;对于隧道中点,各向异性(侧压力系数)对隧道中点处位移的影响与隧道顶点处位移刚好相反;此外,隧道施工中开挖速度、开挖加速度越大,围岩时变位移也越大.

Based on the Maxwell visco-elastic constitutive model and the solution of the anisotropic displacement for surrounding rock,the time-varying analytical solution of anisotropic visco-elastic tunnel excavation are presented through the correspondence principle.The anisotropic stress state means that the lateral earth press coefficient does not equal to 1 in this paper.A variety of ingredients on the displacement of surrounding rock are discussed.The results show that when the anisotropic parameter K〉01,the summit of tunnel will move in the direction of surrounding rock and then change to the opposite direction due to the rheological effect.However,the displacement will generate in the direction of inner tunnel when K0≤1,and the time-varying displacement gradually increases with the decreasing of K0.For the midpoint of the tunnel,the influence of the anisotropic parameter is just opposite to the summit displacement of tunnel.Moreover,the time-varying displacement of surrounding rock would increase with the increase of excavation speed and acceleration.The shear modulus and viscosity also have some influences on the time-varying displacement of surrounding rock.