铁路浅埋偏压隧道稳定性分析及纠偏方案

Stability Analysis of Railway Shallow and Unsymmetrically Loaded Tunnels and Construction Solutions

浅埋偏压段隧道围岩稳定性较差,施工时易发生坍塌、冒顶等事故。基于偏压隧道应力场方程计算,得到隧道施工诱发边坡失稳临界倾角为20°;利用Abaqus有限元程序,研究边坡初始稳定性和隧道施工对边坡稳定的影响。研究结果表明:边坡初始稳定性系数为1.4;隧道施工时,边坡稳定性系数随着应力释放率的增大快速衰减,当应力释放率为10%时,边坡失稳风险激增;隧道拱顶、地中和右拱脚等关键点的沉降均随应力释放率的增大而增大,其中右拱脚处最大、地中处最小,不均匀沉降容易导致隧道衬砌结构开裂;削坡减荷法引起的总沉降量微升,但不均匀沉降显著减小,是较优的隧道偏压纠正方案。

The surrounding rock of shallow and unsymmetrically loaded tunnel has poor stability,which may lead to collapse or roof fall during construction.According to the stress field equation of unsymmetrically loaded tunnel,the critical angle of slope instability induced by construction is 20°;and the Abaqus finite element program is used to study the initial stability of slope and the influence of tunnel construction on slope stability.The results show that the initial stability coefficient of the slope is 1.4;during the construction,the stability coefficient of the slope decays rapidly with the increase of the stress release rate;when the stress release rate is 10%,the risk of the slope instability increases sharply;the settlement of the key points such as tunnel vault,tunnel surrounding mass and the right arch foot increases with the rise of stress release rate,among which the right arch foot has the largest settlement and tunnel surrounding mass has the smallest,and uneven settlement will lead to tunnel lining structure crack;the slope cutting and load reduction method can lead to slight increase in total settlement and significantly reduced uneven settlement,which is an appropriate solution to unsymmetrically loaded tunnel construction.