运营铁路隧道劣化衬砌局部拆换加固关键技术

Key Technology of Partial Replacement of Lining Deterioration in Operating Railway Tunnel

东北地区铁路客运专线WNY隧道某处拱顶存在空洞,空洞范围纵向0.8 m、环向3.0 m,空洞面积2.4 m^(2),衬砌厚度不足。根据衬砌劣化情况及相关要求,采用衬砌局部拆换加固方案整治。通过采用理论分析、数值模拟等方法,对衬砌拆换的全过程进行计算分析,开展拆换加固的可行性研究。结果表明:(1)混凝土拆除置换施工期间,结构最小安全系数为4.33,位于拱腰位置;置换后运营期结构最小安全系数为6.10,位于拱顶位置。施工和运营期结构受力均满足规范要求,混凝土浇筑后有利于结构整体受力,结构受力性能有所改善。(2)环向拆换长度一定时,随着纵向拆换长度的增大,结构首先发生受拉破坏,并通过计算得出一次性最大拆换范围。随着环向拆换长度的增大,纵向允许拆换长度增大,且敏感度逐渐增大。(3)采用5根锚固长度为2.3 m的施工锚杆时,结构整体安全系数为36.75,满足规范要求;采用20 mm厚竹胶板作为浇筑模板时,浇筑模板截面的正应力、剪应力和挠度值均小于规范规定值;化学锚栓支点受力亦小于规范规定值。

Cavity exists in the arch of northeast railway passenger dedicated line WNY tunnel,The cavity range of longitudinal 0.8 m,ring 3.0 m,cavity area of 2.4 m^(2),lining thickness is insufficient.According to the deterioration of the lining and the relevant requirements,the lining was remediated by a partial replacement and reinforcement scheme.By using theoretical analysis and numerical simulation,the entire process of lining replacement was calculated and analyzed,and the feasibility study of removal and replacement for reinforcement was carried out.The results show as follows:(1)During the construction period of concrete removal,the minimum factor of safety of the structure is 4.33,which is located at the hance,and the minimum factor of safety of the structure during the operation period after replacement is 6.10,which is located at the arch crown.The structural stresses during the construction and operation periods meet the specification requirements,and the concrete pouring is conducive to the overall structural stresses.(2)When the ring disassembly length is constant,tensile failure occurs first as the longitudinal disassembly length increases.The longitudinal allowable removal length shows an increasing trend as the ring removal length increases,and the increasing trend is faster and faster.(3)The overall factor of safety of the structure is 36.75 when using five construction bolts with an anchorage length of 2.3 m,which meets the requirements of standard;When 20 mm thick bamboo glue board is used as the lining casting formwork,the positive stress,shear stress and deflection values of the casting formwork section are less than the specified values;The force of a single chemical anchor bolt is also less than the specification value.