基于承载力分析的公路隧道结构健康度评价方法

Health evaluation method of highway tunnel structure based on bearing capacity

目前针对松动荷载作用下隧道结构受力变形与损伤演化机制的研究相对较少,缺乏结构剩余承载力的量化分析依据,不利于结构健康度评价与维修处治方案的确定。针对上述问题,利用室内模型试验及数值仿真手段,研究不同围岩条件下结构受力变形规律及破坏特征,提炼结构健康评价关键指标,建立基于承载力的健康度分级标准。通过研究,提出:(1)拱顶松动荷载下衬砌破坏过程分为3个阶段,以拱顶开裂、主裂缝张开为分界点,破坏时拱顶内侧、拱腰外侧钢筋拉断,形成三铰拱体系;(2)衬砌结构承受相同荷载100kPa时,抗力系数1.58MPa/m的工况拱顶下沉3.3cm,抗力系数200MPa/m的工况拱顶下沉0.23cm;抗力系数从1.58MPa/m增大到200MPa/m时,极限承载力从196kPa增大到1840kPa;(3)以衬砌开裂、拱顶下沉3cm、拱顶钢筋屈服、拱腰钢筋屈服、拱顶钢筋拉断为关键节点,建立衬砌结构健康度的5级划分标准,并以拱顶下沉及边墙收敛作为简易评价指标,对V^VI级围岩,拱顶下沉控制值建议取5cm。

At present,the research on the deformation and damage evolution mechanism of tunnel structures under the action of loose load is relatively scarce,and the quantitative analysis of structural residual bearing capacity is lacking,which is not conducive to of structural health assessment and the determination of maintenance treatment program. For these problems,this paper studied the deformation regularity and damage characteristics of the structure under different surrounding rock conditions,summarized the key indexes of structural health assessment,established the standard of health classification based on bearing capacity through indoor model test and finite element analysis software. Through these researches,we can draw the following conclusions.(1) The failure process of the lining is divided into three stages,the arch cracking and the main crack opening as the dividing line. The inner side of the vault and the outside of the arch pull the steel bar apart,the structure turned into three-hinged arch at the same time.(2) Arch crown settlement is 3.3 cm with resistance coefficient 1.58 MPa/m and 0.23 cm with resistance coefficient 200 MPa/m under the same load of 100 kPa. Resistance coefficient increases from 1.58 MPa/m to 200 MPa/m,the ultimate bearing capacity increases from 196 kPa to 1 840 kPa.(3) Through taking lining cracking,crown sinking 3 cm,arch crown steel yield,arch haunch steel yield and arch crown steel breaking as key nodes,and taking crown settlement and side wall convergence as simple evaluation indexes,the 5 grade criterion of lining structure health degree is established. The control value of crown settlement for V–VI grade surrounding rock is suggested to take 5 cm.