双回路超高压电缆浅埋暗挖隧道断面优化设计

Optimal design of the shallow buried covered excavation tunnel which used double circuit EHV cable transmission lines

根据现有的技术手段,在软土地区修建专用电缆隧道一般采用顶管法或盾构法,而在硬质岩地区则选用浅埋暗挖法。一般情况下,电缆隧道周边的构筑物或管线对地层变形允许值要求都比较高,当浅埋暗挖电力隧道采用国家电网公司推荐的直墙拱形断面时,隧道施工引起的周边地层变形都较大,实施过程往往需要迁改地下管线。在对双回路超高压电力电缆空间需求分析的基础上,优化隧道内的电缆及其附属设施的布置方案,而后采用三心圆法绘制曲墙拱形的浅埋暗挖隧道断面;与此同时,采用数值分析方法对隧道施工过程引起的周边地层变形进行模拟。分析结果显示:采用三心圆形法的隧道断面较直墙拱形隧道断面减小周边地层变形量达15%以上,带来了良好的环境效益;研究结果指导工程建设,并为类似工程建设提供参考。

As common technology,the pipe jacking method or the shield method has been used usually in the tunnel construction in the soft clay district,and the shallow buried covered excavation method is been application in the hard rock district. The environment of the EHV cable tunnel is usually full of pipe lines or underground structures,which require high of the deformation cased by the tunnel excavation. According to the experience of the shallow buried excavation tunnel,the deformation has a great chance to go beyond the design control value,which makes a lot of pipe lines or the underground structures have to be modified. Based on space requirement anlysis of two extra high voltage cable lines,arrange the cable and the ancillary facilities inside the tunnel was optimized,and then the tunnel cross section into arc sidewall by three circle method was drawed,finialy,the deformation caused by the tunnel excavation was simulated by finite element method. The simulation results show that,the three circle method tunnel could reduce the deformation into15% of the straight sidewall,which takes great environment benefits. The research can guide the design of the tunnel design and provide references for similar construction.