新建高速公路隧道上跨既有引水隧洞安全性分析与评价  

Safety Analysis and Evaluation of Newly-built Expressway Tunnel over Existing Headrace Tunnel

作　　者：王希宝 袁松 陈文宇 张生 Wang Xibao;Yuan Song;Chen Wenyu;Zhang Sheng(Sichuan Communication Surveying&Design Institute Co.,Ltd.,Chengdu 610017,China;Sichuan Highway Planning Survey and Design Research Institute Co.,Ltd.,Chengdu 610041,China)

机构地区：[1]四川省交通勘察设计研究院有限公司,成都市610017 [2]四川省公路规划勘察设计研究院有限公司,成都市610041

出　　处：《北方交通》2021年第11期74-78,共5页Northern Communications

基　　金：四川交通运输科技项目(2020-B-01);2020年度交通运输行业重点科技项目(2020-MS3-101);四川交通运输科技项目(2019-ZL-12)。

摘　　要：新建隧道近距离上跨既有运营隧洞必然改变既有隧道(洞)的地应力场,衬砌结构受力状态也将发生改变,同时新建隧道施工作业(爆破)冲击荷载也会影响既有隧道(洞)衬砌结构。为确保既有隧道(洞)安全,需要对新建隧道施工及隧道建成后对既有隧道(洞)的影响进行全面评估。以某高速公路近距离上跨既有引水隧洞为例,介绍了评估过程及评估方法。结果表明:左洞施工应超前掘进,与右洞相距至少100 m;成绵扩容隧道施工过程中所允许的最大用药量为30.66kg;为进一步保证在隧道施工过程中引水隧洞的结构安全,在施工到达引水隧道上方时,可采用增加台阶步数或缩短进尺等方式,进一步减少爆破装药量从而减轻爆破振动。The newly-built tunnel over the existing operating tunnel portal in a short distance will inevitably change the in-situ stress field of the existing tunnel(portal),and the stress state of the lining structure will also change.At the same time,the impact load of the newly-built tunnel construction(blasting)will also affect the lining structure of the existing tunnel(portal).In order to ensure the safety of the existing tunnel(portal),it is necessary to comprehensively evaluate the impact of the construction of the newly-built tunnel and that on the existing tunnel(portal)after the completion of the newly-built tunnel.Taking an expressway over the existing headrace tunnel in a short distance as an example,the evaluation process and evaluation method are introduced.The results show that,the left portal construction should be excavated in advance,at least 100m away from the right portal;the maximum allowable dosage during the construction of Chengdu-Mianyang expansion tunnel is 30.66kg;in order to further ensure the structural safety of the headrace tunnel during the tunnel construction,the steps can be increased or the footage can be shortened to further reduce the blasting charge when the construction reaches the upper part of the headrace tunnel,so as to reduce the blasting vibration.

关 键 词：新建隧道 上跨既有引水隧洞 安全性评价 

分 类 号：U458[建筑科学—桥梁与隧道工程]