不同地形偏压与隧道受力变形的关系

Relationship Between Different Slope Bias Pressure and Deformation and Mechanics of Tunnel

为了研究由地表倾斜引起的偏压对隧道受力、变形特性的影响,依托三卿口隧道工程实例,针对洞口浅埋偏压地段,基于平面应变问题,数值模拟了地表倾角为0°、5°、……、45°共计10种工况.结果表明:地表倾角小于35°时,隧道的拱顶沉降、周边收敛、衬砌弯矩、衬砌轴力变化较小,而当地表倾角大于35°时,各数值急剧增加;偏压情况下隧道的敏感部位为左墙脚、左边墙、左拱脚、右拱脚,而且在倾角大于35°时,左拱脚弯矩出现反号(内侧受压,变为内侧受拉).建议在隧道设计、施工中,当地表倾角小于35°时(相当于地面坡度1∶1.4),可以不考虑地形偏压对隧道的影响,反之,则要考虑.

Based on a plain problem, a simulation of ten cases （with slope angle 0°, 5°,... , 45°） were carried out on a Shallow tunnel under bias pressure to study the influence of different bias pressure on tunnel internal forces and rock deformation. The results show： when the slope angle is less than 35°, there is a little increase in crown displacement, convergence, lining bending moments and lining axial forces; however, if slope angle greater than 35°, there is significant increase with the most sensitive parts locating left foot corner, left sidewall, left arch foot and right arch foot. Meanwhile, direction of bending moments, in left arch foot, is reversed. Some proposals, on tunnel design and construction, are therefore suggested： it is unnecessary to take bias pressure into account if the surface slope angle is smaller than 35° , otherwise, bias pressure should be considered with special attention to sensitive parts.