考虑基础刚度的新型高填方双层衬砌式明洞的动态力学特性  

Dynamic Mechanical Property of New Type of High Fill Open Cut Tunnel with Bi-Layer Lining Considering Foundation Stiffness

作　　者：王明年[1,2] 徐湉源 于丽[1,2] 罗勇[1,2] 

机构地区：[1]西南交通大学土木工程学院,四川成都610031 [2]西南交通大学交通隧道工程教育部重点实验室,四川成都610031

出　　处：《中国铁道科学》2017年第1期68-76,共9页China Railway Science

基　　金：中国铁路总公司科技研究开发计划项目(2014G010);重庆市应用开发计划重点项目(cstc2014yykfB30003)

摘　　要：为解决高填方明洞整体式衬砌过厚导致的水化热裂缝问题,在渝利铁路重庆丰都高填方明洞工程中首次采用双层衬砌设计,通过现场实测及数值模拟2种方法分析该新型结构的动态力学特性。结果表明:在回填土达到明洞顶部前,即仅有侧向荷载时,明洞结构的内力增量很小,在回填高度超过明洞顶部后,明洞的内力则随回填高度的增加而线性增长;双层衬砌明洞的外衬和内衬的轴力之比接近二者的厚度之比,而二者的弯矩之比则无类似规律,二者的相互作用方式与组合梁类似;采用混凝土坝基础时一定程度上增大明洞的荷载,其上明洞的轴力和弯矩分别为软岩基础上明洞的1.2~1.6倍和1.6~2.4倍;明洞拉应力集中现象主要出现在边墙位置。建议对混凝土坝基础上的明洞采取减载和优化边墙结构措施。To solve the problem of hydration heat crack caused by the thick monolithic lining of high fill open cut tunnel,bi-layer lining was first adopted in the design of high fill open cut tunnel in Fengdu Chongqing of Chongqing-Lichuan Railway.Field tests together with numerical simulation were adopted to analyze the dynamic mechanical properties of this new structure.Results show that,before the backfill reaches the top of open cut tunnel,namely,when there is lateral load alone,the internal force increment of open cut tunnel structure is very small.However,after the backfill reaches the top of open cut tunnel,the internal force of the structure increases linearly with the increase of backfill height.The axial force ratio between the outer lining and inner lining of open cut tunnel with bi-layer lining is close to their thickness ratio,while their bending moment ratio has no similar law.Their interaction is similar to that of composite beam.Concrete dam foundation can improve the load of open cut tunnel to a certain extent.The axial force and bending moment of the open cut tunnel on concrete dam foundation is respectively 1.2-1.6and 1.6-2.4times of that on soft rock foundation.The tensile stress concentration of open cut tunnel occurs mainly at the side wall.It is suggested that such measures as load reduction and optimization of side wall structure should be taken for the open cut tunnel on concrete dam foundation.

关 键 词：高填方明洞 双层衬砌 动态力学特性 软岩基础 混凝土坝基础 

分 类 号：U449.81[建筑科学—桥梁与隧道工程]