隧道前方大型溶洞对隧道围岩稳定性影响

在尚家湾隧道施工期间,曾预报并揭露大型溶洞,溶洞的存在给隧道施工带来极大的安全隐患。以尚家湾隧道为背景,开展数值试验。通过对比隧道前方有、无溶洞条件下开挖工况,从位移、应力、塑性区3个方面分析了隧道前方大型溶洞对隧道围岩稳定性的影响。研究表明:对于本工程而言,溶洞对隧道底部和左侧拱腰的影响要大于对隧道顶部及右侧拱腰的影响;隧道前方存在大型溶洞条件下塑性区体积随开挖位置呈指数增长。隧道前方无溶洞条件下,塑性区体积随开挖位置呈线性增长,即溶洞的存在大大加速了隧道开挖塑性破坏区的增长。该研究对岩溶地区隧道安全施工具有一定的指导意义。

The influence of large karst cave ahead of tunnel face on stability of surrounding rock masses

In order to Shangjiawan tunnel as the background, once forecasted and exposed large karst cave during Shangjiawan tunnel construction, the existence of the karst cave brought huge potential safety hazard to tunnel construction, numerical experiment research was carried out on the influence of large karst cave ahead of tunnel face on stability of surrounding rock masses from the displacement, stress and plastic zone through the comparative analysis with no cave conditions. To the actual engineering, the influence of large karst cave on bottom and left haunch were bigger than top and right haunch situation through displacement and stress analysis. The plastic zone increased exponentially under the condition of karst cave and increased linearly under the condition of no cave, all of this show that the existence of karst cave had greatly accelerated the growth to the plastic area. The study had certain guiding significance to the safety of tunnel construction in karst area.