溶洞对隧道结构变形与受力特征的影响研究--以大方隧道为例

Impact of Karst Cave on Tunnel Structure Deformation and Stress:a Case Study of the Dafang Tunnel

为探究溶洞对隧道结构变形与受力特征的影响,采用数值模拟方法,通过改变溶洞分布位置、尺寸大小以及与隧道结构净距等不同因素,建立了二维有限元模型,分析了溶洞对隧道结构位移与内力的影响。结果表明:溶洞使隧道结构变形与受力发生了改变,伴随溶洞与隧道距离的增大,隧道结构产生的位移逐渐减小,在同一净距下,随溶洞尺寸增大隧道结构位移逐渐增大,与无溶洞工况对比,溶洞使得隧道结构内力发生了重新分布,在靠近溶洞一侧隧道结构变形与内力均较大。当溶洞直径小于0.4倍隧道尺寸时,溶洞对隧道结构变形与内力影响均较弱,当溶洞直径大于0.6倍隧道尺寸,且与隧道净距小于0.3倍隧道尺寸时,溶洞对隧道结构变形与内力影响显著,最后通过对比分析,得出对隧道稳定性最不利的溶洞位置是隧道侧部溶洞。研究成果可为岩溶隧道设计施工提供科学参考和借鉴。

To explore the influence of karst cave on deformation and stress characteristics of tunnel structure, two-dimensional finite element model was established in numerical simulation method by changing the location, size, and net distance of the tunnel, in which the displacement and internal force of the tunnel structure was analyzed in a case study of the Dafang Tunnel, Guizhou, SW China. Results show that the local karst caves could alter the deformation and stress of the tunnel structure. As the distance between cave and tunnel increased, the displacement of the tunnel structure was reduced gradually. Under the same clearance, the displacement of the tunnel structure increased with the increase of the cave size. Compared with the no-karst-cave working conditions, the karst cave caused the redistribution of the internal force of the tunnel structure. The deformation and internal force of the tunnel structure proximal the karst cave were larger. When diameter of the cave was less than 0.4 times of the tunnel size, influence of the cave on the deformation and internal force was weak;while when the diameter was greater than 0.6 times the tunnel size and the net cave-tunnel distance was less than 0.3 times the tunnel size, the cave could have a significant influence on the deformation and internal force of the tunnel structure, which may become a construction risk zone. It was concluded that the most unfavorable cave to tunnel stability was those lateral to tunnel. This research may provide a scientific reference for tunnel design and construction in karst regions.