基于Abaqus模拟的不良地质特征对隧道衬砌结构影响的分析研究

Analysis and Research on Influence of Unfavorable Geological Characteristics on Tunnel Lining Structure Based on Abaqus Simulation

为研究穿越溶洞不良地质因素的高速公路隧道衬砌结构应力稳定性,利用Abaqus数值平台开展了溶洞分布方位、溶洞净距因素的影响下衬砌结构断面上大、小主应力变化的分析。衬砌断面上大、小主应力均呈“双U”形特征,而溶洞方位角90°、270°下衬砌断面大主应力水平最高,而小主应力以此两方案下最低;溶洞分布在此两方位上,对隧道衬砌结构应力稳定性影响最大。溶洞净距每增大3 m,衬砌断面上平均大、小主应力分别可减小27.9%及增大45.8%;净距愈小,谷值大、小主应力段持续面分别为更小与更大趋势;净距参数对衬砌结构影响集中在量值水平与谷值分布。隧道穿越的溶洞净距过小,应考虑技术处理降低其敏感影响。总结的经验可为桥隧工程中研究溶洞等不良地质特征影响提供参考。

In order to study the stress stability of the lining structure of the expressway tunnel crossing the unfavorable geological factors of the karst cave,the Abaqus numerical platform was used to analyze the changes of large and small principal stresses on the lining structure section under the influence of the distribution orientation of the karst cave and the clear distance of the karst cave.The large and small principal stresses on the lining section are characterized by a"double U"shape,while the large principal stress level of the lining section is the highest under the azimuth angles of 90°and 270°of the karst cave,while the small principal stress level is the lowest under these two schemes.The distribution of karst caves in these two directions has the greatest impact on the stress stability of tunnel lining structure.The average large and small principal stresses on the lining section can be reduced by 27.9%and increased by 45.8%when the clear distance of karst cave increases by 3 m.With decreasing the clear distance,the trough value and the small principal stress stage become smaller and larger,respectively.The influence of clearance parameters on the lining structure is concentrated on the magnitude level and valley value distribution.The clear distance of the karst cave that the tunnel passes through is too small,thus the technical treatment should be considered to reduce its sensitive impact.The summarized experience can provide reference for the study of adverse geological characteristics such as karst caves in bridge and tunnel projects.