大跨度四线铁路车站隧道内轮廓研究

对于大跨度四线隧道,相比传统单、双线铁路隧道,其开挖跨度及开挖面积要大得多。一方面,为提高隧道空间的利用率、降低工程成本,其断面形式将更加扁平,开挖后的应力重分布状态恶化,增加了隧道结构设计和施工的难度。反之,单纯从受力考虑,衬砌结构宜采用近圆形的内轮廓,导致空间利用率降低,开挖量及圬工大幅度增加,势必产生浪费,增加成本。基于贵昆铁路六盘水至沾益段增建二线上的乌蒙山2号四线车站大跨度隧道,在满足建筑限界及相关作业要求条件下,在技术可行、经济合理的范围内,通过对大跨度四线隧道不同扁平率洞室的围岩应力、位移及塑性区,衬砌结构的承载力及经济性对比等进行研究,以确定经济合理的衬砌内轮廓及其扁平率范围,为特大跨度隧道衬砌内净空拟定提供参考与指导。

Research on Inner Contour of Large-span Four-track Railway-station Tunnel

Compared with traditional single and double track railway tunnels,the span and the excavation area of the large-span four-track railway tunnel are much larger. In order to improve the utilization ratio of tunnel space and reduce project cost,the section of the tunnel becomes more flat,and the stress redistribution after tunnel excavation would be worse,which add more difficulties to structural design and construction. On the contrary,in view of the pure stress,the lining structure should be the inner contour of near round,which results in low space utilization rate,substantial increase of excavation and masonry,production waste and additional cost. With reference to the construction of No.2 Wumengshan large-span four-track railway-station tunnel,reasonable inner contour and the range of flat ratio are determined based on the analysis and comparison of the stress,displacement and plastic zone of surrounding rock,and the carrying capacity and economy of the lining structure to meet the operational requirements of construction clearance and related conditions. This research provides some references for determining inner clearance of Large-span tunnel lining.