既有连拱隧道与新建特大跨度隧道的净距研究

Study on the Clear Distance between the Existing Multi-arch Tunnel and the Newly Built Extra-large Span Tunnel

广州市华南快速路石门堂山隧道扩建工程,为在既有连拱隧道侧新建的特大跨度单洞四车道隧道,既有连拱隧道存在衬砌裂缝、防火涂料脱落等病害,且在新建隧道施工过程中需要保通运营,同时受周边土地资源紧张限制,因此开展新建隧道与既有连拱隧道的净距研究是十分有必要的。通过对新建隧道的爆破振动安全允许距离进行计算,最终选取36.8m的安全净距,利用MIDAS GTS NX有限元软件对爆破荷载作用下的既有连拱隧道的内力进行分析,从而验证所设计的隧道净距。结果表明:在考虑对既有隧道的变形、衬砌应力影响下,新建隧道与既有隧道净距设为36.8m对既有连拱隧道的影响是较小的,为隧道结构的设计提供参考依据。

The expansion project of Shimentangshan Tunnel of South China Expressway in Guangzhou is a new extra-large-span single-hole four-lane tunnel on the side of the existing continuous arch tunnel,which has diseases such as lining cracks and falling off of fireproof paint,and needs to guarantee normal operations during the construction of the new tunnel,and is limited by the shortage of surrounding land resources,so it is necessary to carry out the study of the clear distance between the new tunnel and the existing continuous arch tunnel.By calculating the safe allowable distance of blasting vibration for the new tunnel,determining the safe clearance of 36.8 m,and analyzing the internal forces of the existing continuous arch tunnel under blasting load using the MIDAS GTS NX finite element software,the designed tunnel clearance is verified.The results show that considering the influence of deformation and lining stress on the existing tunnel,the clear distance between the new tunnel and the existing tunnel is set to 36.8 m on the existing multi-arch tunnel,which provides a reference for the design of tunnel structure.