基于弹性极限理论的盾构隧道收敛变形研究

为研究隧道横向收敛变形对隧道结构安全的影响,从变形协调的角度出发,应用修正惯用法求出螺栓在弹性极限状态下管片截面的弯矩值,并根据管片横截面受力与隧道横向变形之间的关系,反推出管片环的弹性极限曲率半径。基于上海地铁单圆隧道的设计参数,对弯矩传递系数ξ分别取0.3、0.4及0.5进行计算,得出隧道收敛变形的限制值分别为18.6mm、23.4mm及30.2mm。最后,以上海轨道交通8号线某区间隧道的实测横向收敛数据为基础,将该方法得出的限制值与设计控制值5‰D(D为隧道外径)进行了对比。通过对比表明:该收敛变形的限制值能够反映出管片接头处螺栓的受力状况,可以为地铁运营隧道的安全评判提供重要参考。

Research on Convergence Deformation of Shield Tunnel with Elastic Limit Theory

To study the influence of tunnel convergence deformation to tunnel structure,modified routine method has been used to calculate segment’s cross-section moment when the connected bolt is in the elastic limit state.According to the relationship between segment deformation and stress of cross-section,the segment’s elastic limit curvature radius has been derived.Based on the design parameters of Shanghai Metro tunnel,the limit value of segment curvature radius has been received.When moment transfer coefficient ξ is equal to 0.3,0.4 and 0.5 respectively,the variation limit value of segment curvature radius is 18.6mm,23.4mm and 30.2mm.At last,the elastic limit value and the design requirements’ value have been compared base on the measured data of a tunnel in Shanghai Metro Tunnel-Line 8.It is suggested that elastic limit value could reflect bolt’s stress status in the segments’ joints,and could provide important reference for the tunnel’s security evaluation.