近接溶洞对隧道开挖稳定性影响分析

Analysis of the Stability Influence of the Nearby Karst Cave on the Tunnel Excavation

【目的】为了研究拱顶近接溶洞对隧道开挖稳定性的影响规律。【方法】本研究以西南地区某隧道工程为依托,采用数值模拟方法,对不同工况下的隧道开挖稳定性进行模拟分析。【结果】隧道拱顶处揭露小型溶洞时(近接距离>2 m),拱顶位移量及衬砌支护结构拉压应力值皆减小,变化幅值与近接距离成反比,且均在10%以内;当隧道与溶洞近接距离小于2 m时,支护结构所承担的拉压应力虽减小,但拱顶位移量随之增大,间距内的围岩极易出现塑性区贯通现象,支护体系的完整性遭到破坏,须提前做好超前支护及开挖后的支护措施。【结论】研究成果可为类似岩溶地区支护设计及施工措施的优化提供参考。

[Purposes]This paper aims to investigate the influence of the proximity of karst caves to tunnel arches on excavation stability.[Methods]A numerical simulation method was used to analyze the excavation stability of the tunnel under different working conditions,based on a tunnel project in the southwest region of China.[Findings]When small karst caves are exposed at the tunnel arch(proximity distance>2 m),the displacement and tensile and compressive stress values of the lining support structure at the arch are reduced.The change pattern is inversely proportional to the proximity distance,and the amplitude is within 10%.When the distance between the tunnel and the cave is less than 2 m,the tensile and compressive stress borne by the tunnel support structure decreases,but the displacement of the arch increases.The surrounding rocks within the distance are prone to plastic zone breakthrough,and the integrity of the support system is damaged.Therefore,advanced support and post-excavation support measures should be taken.[Conclusions]The research results can provide reference for the optimization of support design and construction measures in similar karst areas.