双跨连拱隧道两种中墙的空间力学效应分析

Three-dimensional mechanical effect analysis of two types of midboard for double span-arch-connecting tunnel

针对双跨连拱隧道设计和施工中存在的问题,采用三维有限差分程序FLAC3D2.0,对两种中墙结构的空间受力特征进行了研究,对比分析各自的优缺点及适用条件,并提出了施工注意事项。研究结果表明,在II类围岩地质条件下浅埋连拱隧道采用分离式曲中墙结构受力较为合理;左洞掌子面距研究断面3倍洞径时,中墙内力已稳定;左右洞掌子面距研究断面(-1～+1)D的施工,是中墙内力变化较大的关键工序。

Aiming at open problems in the design and construction of double span arch-connecting tunnel, a research on three-dimensional stress characteristics of two types midboard is carried out by means of finite difference method FLAC^3D2.0; and their merits and demerits, as well as applicable conditions are analyzed. The result shows that stress of separated type curved wall is more proper than integral type stalk on shallow depth double span arch-connecting tunnel in the condition of II type rock; inner force of midboard has been in stabilization when left cavern heading face drives to three times diameter from researched cross-section; while right and left cavern heading face drives to （-1-1）D time diameter from reseached cross-section, inner force of midboard greatly changes, and these constructions are key processes.