摘要
新建隧道大角度上跨施工易对下方既有隧道结构造成不利影响,为了确保既有隧道运营安全,需对新建隧道上跨后的既有隧道结构安全性进行评价。依托重庆至黔江铁路徐家堡隧道工程,借助有限元软件MIDAS分别构建地层结构模型和荷载结构模型,对新建隧道上跨修建后既有隧道围岩变形、结构受力及安全系数进行系统分析。研究结果表明:由于上方土体大量卸荷,下方既有隧道整体发生隆起变形,最大变形位于仰拱处,增量为1.173 mm,现场沉降监测验证了数值计算的合理性。新建隧道的施工破坏了既有隧道的承载拱效应,导致结构受力增加,但均小于安全限值;荷载结构法表明,公路隧道修建前后下方铁路隧道结构最小安全系数分别为7.05、4.73,说明公路隧道的修建对铁路隧道有一定影响,但仍在安全可控范围内。
The construction of a newly-built tunnel with a large angle is easy to adversely affect the existing tunnel structure.In order to ensure the operation safety of the existing tunnel,it is necessary to evaluate the safety of the existing tunnel structure.Based on the Xujiabao Tunnel Project of Chongqing-Qianjiang Railway,this paper applies the finite element software MIDAS to construct the stratum structure model and the load structure model respectively,to systematically analyze the deformation of surrounding rock,structural stress and safety factor of the existing tunnel after the construction of the newly-built tunnel.The results show that due to the large unloading of the overlying soil,the existing tunnel below experiences an uplift deformation as a whole,and the maximum deformation locating at the inverted arch,with an increment of 1.173 mm.The rationality of numerical calculation is verified by field settlement monitoring.The construction of the new tunnel destroys the bearing arch effect of the existing tunnel,which leads to the increase of the structural stress,but it is less than the safety limits.The load structure method shows that the minimum safety factors of the lower railway tunnel structure before and after the construction of the highway tunnel are 7.05 and 4.73,respectively,indicating that the construction of the highway tunnel has a certain impact on the railway tunnel,but it is still within the safe and controllable range.
作者
王开阳
WANG Kaiyang(China Railway 18th Bureau Group Tunnel Engineering Co.,Ltd.,ChongQing 401135)
出处
《国防交通工程与技术》
2024年第1期52-55,92,共5页
Traffic Engineering and Technology for National Defence
关键词
隧道工程
上跨
数值分析
沉降监测
安全系数
tunnel engineering
overcross
numerical analysis
settlement monitoring
safety factor
