作　　者： ; ; ;

机构地区： 同济大学

出　　处： 《现代隧道技术》 2020年第1期26-35,共10页

摘　　要： 目前关于大跨隧道结构在松动荷载作用下的受力变形与损伤演化机理研究相对较少,缺乏运营期隧道结构的健康度评价体系与预警标准,不利于掌握隧道结构的安全状态。针对上述问题,文章通过建立二维及三维数值分析模型,研究了Ⅳ级、Ⅴ级围岩下大跨隧道结构在松动荷载下的受力变形特性,并依据变形及破损特征,建立了5级评价体系与3级预警标准。研究结论为:(1)拱部松动荷载作用下大跨隧道的破坏过程分为四个阶段,分别为设计荷载下的弹性受力阶段、拱部松动荷载下的弹性受力阶段、结构开裂后的塑性工作阶段及加速变形破坏阶段;(2)设计荷载下,采用荷载规范计算方法与三维数值模拟方法得出的隧道变形基本一致,验证了数值计算的可行性。通过数值计算,得出Ⅳ级围岩下结构极限承载力为734 kPa,拱顶沉降6.75 cm,边墙收敛1.56 cm。Ⅴ级围岩下结构极限承载力为812 kPa,拱顶沉降10.47 cm,边墙收敛4.06 cm;(3)以拱顶开裂、局部压屈、拱顶拱腰压屈、拱腰压屈达到衬砌厚度的1/3、钢筋拉断为关键节点,以结构受力、拱顶沉降、边墙收敛为评价指标,建立了Ⅳ级、Ⅴ级围岩下大跨隧道的健康度评价体系及预警标准。 At present,there are few research on the mechanism of deformation and damage evolution of large-span tunnel structure under loose load,lacking health evaluation system and early warning standard of the tunnel struc⁃ture in operation,which is not conducive to understand the safety state of tunnel structure.Aiming at these prob⁃lems,this paper studies the mechanical and deformation characteristics of large-span tunnel structure under loose load in the surrounding rocks of gradeⅣandⅤby establishing two-dimensional and three-dimensional numerical analysis models.A 5-grade evaluation system and 3-level early warning standard are established based on the char⁃acteristics of deformation and damage.It comes to the following conclusions:(1)the failure process of the large-span tunnel under loose load is divided into four stages,namely elastic stress stage under designed load,elastic stress stage under loose load,plastic working stage after structure cracking and accelerated deformation and failure stage;(2)under designed load,the tunnel deformation obtained by three-dimensional numerical simulation method is basi⁃cally consistent with that by the calculation method of load code,which verifies the feasibility of numerical calcula⁃tion.By numerical calculation,it is found that in the surrounding rocks of gradeⅣ,the ultimate bearing capacity is 734 kPa,the crown settlement is 6.75 cm,the convergence of sidewall is 1.56 cm;in the surrounding rocks of grade V,the ultimate bearing capacity is 812 kPa,the crown settlement is 10.47 cm,the convergence of side-wall is 4.06 cm;(3)a health degree evaluation system and early warning standard of large-span tunnels in the surrounding rocks of grade IV and V are established by taking the vault cracking,local buckling,vault and haunch buckling,haunch buckling depth reaching 1/3 of lining thickness and rebar tensile rupture as the key nodes and structure stress,crown settlement and side-wall convergence as the evaluation indexes.

关 键 词： 大跨隧道 衬砌结构 健康度 破碎围岩 松动荷载

领　　域： []