随着目前公路隧道跨度越来越大,而超大跨扁平隧道由于其特殊的形状,使得拱部受力较上圆形隧道更为不利且开挖的影响范围也更大,因此现有深浅埋分界方法的适用性尚需考证.研究采用数值计算与经验公式方法,对比不同跨度、不同围岩级别下超大跨扁平隧道的深浅埋分界,得到适用于此工程的判定方法,同时确定其深浅埋分界范围.研究结果表明:1)主应力旋转轴理论与规范经验法相互补充、相互验证,具有着一定的可操作性,大跨扁平隧道深浅埋分界的判定应结合2种方法综合得到;2)当隧道跨度在19m左右时,Ⅲ级围岩深浅埋分界值为6m,Ⅳ级围岩深浅埋分界值为14m,Ⅴ级围岩深浅埋分界值为 34 m.
RESEARCH ON SHALLOW AND DEEP BURIAL DETERMINATION OF LARGE CROSS-SECTION TUNNELS BASED ON SURROUNDING ROCK STRESS
With the increasing span of highway tunnels at present,super-span flat tunnels,due to their special shape,have more unfavorable forces on the arch and larger influence area of excavation than circular tunnels.Therefore,the applicability of the existing deep and shallow buried boundary method needs to be verified.This paper uses numerical calculation and empirical formula to compare the deep and shallow buried boundaries of super-span flat tunnels with different spans and different surrounding rock levels,and obtains a judgment method suitable for this project,and determines the range of deep and shallow buried boundaries.The results show that:1)the principal stress rotation axis theory and the standard empirical method complement and verify each other,and have certain operability.The determination of the deep and shallow buried boundary of long-span flat tunnels should be combined with the two methods.2)When the tunnel span is about 19 m,the deep and shallow buried boundary value of the Ⅲ level surrounding rock is 6 m,the Ⅳ level surrounding rock is 14 m,and the Ⅴ level surrounding rock is 34m.
万方数据
维普
