【摘要】 以江西某高速公路一浅埋偏压连拱隧道为背景,用Marc有限元程序对其出口段进行了动态施工的三维数值模拟。从施工过程中的应力(剪应力和正应力)集中、塑性区的分布形态和发展规律、仰坡轴向和横向地表位移的分布特征等方面,系统研究了偏压连拱隧道强风化仰坡因施工而引起的失稳机制。结果表明:(1)塑性区和应力集中区在模拟施工过程中只出现在洞体附近,可能的仰坡失稳往往是隧道施工失稳的累进性响应,机制是:隧道开挖引起近洞区的塌落和挤出破坏,从而扰动相对较远的仰坡,削弱甚至破坏其稳定性;(2)隧道上方和近山脊一侧仰坡轴向和横向位移比近山谷一侧的大,仰坡失稳往往从隧道上方和埋深较大一侧开始;(3)洞口仰坡的轴向水平位移前缘大,后缘小,垂直位移后缘大,前缘小,与圆弧型剪切滑移边坡的位移模式很吻合。更多还原

【Abstract】 Taking one expressway in Jiang Xi province as the engineering background,this article simulates the construction effect on mouth slope for one shallow-embedded and double-arch tunnel with partial-pressure.Several aspects,such as stress concentration,plastic zone distribution,ground displacement along the axial and transverse slope axis,are studied particularly and systematically and it is found that the stress is concentrated and the plastic zones are distributed only near the tunnel lining,the slope failure is a gradual and accumulated response to the tunnel failure during construction.The response mechanism is: the excavation causes the rock and soil near the tunnel to be caved in,disturbing the relatively far slope and impairing its stability.The axial or transverse displacement is more prominent for the slope between tunnel and mountain ridge,which may fail firstly,then follows the one between tunnel and mountain vale.For the slope at the tunnel mouth,the displacement mode along main slope axis is similar or identical to that of a slope which is slipping or shearing out along a curved surface.The vertical displacement of back slope is bigger than that of the frontal one and for horizontal displacement,it is just the opposite.更多还原