寒区隧道围岩水热力耦合数值分析

发布时间：2018-01-31 20:39

本文关键词： 寒区隧道水热力耦合冻融循环数值分析　出处：《西安科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着“一带一路”战略的深入实施,越来越多的岩土工程建设必须在高海拔、严寒等极端条件下进行,冻融灾害是寒区岩土工程的突出问题。冻融环境下,岩体骨架、冰晶体、未冻水这三种物质在温度、土水势、压力与变形等外界因素作用下,相互运动、迁移、扩散与相变,水热力状态相互耦合、相互影响。因此,从水热力耦合的角度研究岩土工程结构的稳定性具有重要的理论及工程意义。本文以西藏“扎墨”公路嘎隆拉隧道为依托,采用有限单元法,对寒区隧道围岩的单应力场、温度场、渗流场进行数值计算,分析了应力和位移、冻深、孔隙压力和渗流速度的分布规律;对寒区隧道围岩多场耦合问题进行数值计算,分析了应力场、温度场、渗流场的相互影响及变化规律。研究表明:由于隧道开挖引起的应力重分布,隧道断面围岩拱顶下沉,仰拱隆起;隧道周边围岩出现季节性冻融圈,最大冻深出现在拱顶处;最大渗流速度发生在边墙墙脚处,开挖断面附近渗透压力等位面密集,水力坡降大,对岩体的渗透动水压力较大;由于埋深较浅,围岩拱顶区域受隧道内壁和山体表面气温双重影响,冻融破环极度严重;在水热力耦合的作用下,隧道围岩冻深减小,位移及应力增大;经过10年的运营,隧道围岩拱顶下沉量由0.89mm增大为1.89mm,衬砌的最大拉应力从0.4MPa增大到了1.3MPa,可见冻融循环对围岩及衬砌力学特性影响较大;在寒区隧道设计和施工过程中,必须考虑冻胀力的作用,必须考虑温度场、水分场和应力场的相互影响。为减少寒区隧道冻融灾害,应在隧道洞口和内壁采取良好的保温措施,减小洞内外气温与围岩间的热交换;结合注浆堵水、铺设防水层、设置排水边沟等措施,减小衬砌内外侧的热交换。
[Abstract]:With the further implementation of "Belt and Road" strategy, more and more geotechnical engineering construction must be carried out under extreme conditions such as high altitude, severe cold and so on. Freezing and thawing disaster is a prominent problem in geotechnical engineering in cold region. Rock skeleton, ice crystal and unfrozen water are coupled with each other under the action of temperature, soil water potential, pressure and deformation. Therefore, it is of great theoretical and engineering significance to study the stability of geotechnical engineering structure from the point of view of hydro-thermal coupling. Based on the Kalongla Tunnel of Zamo Highway in Tibet, the finite element method is adopted in this paper. The single stress field, temperature field and seepage field of tunnel surrounding rock in cold region are numerically calculated, and the distribution of stress and displacement, freezing depth, pore pressure and seepage velocity are analyzed. The coupling problem of multi-field in tunnel surrounding rock in cold region is numerically calculated, and the interaction and variation of stress field, temperature field and seepage field are analyzed. The research shows that the stress redistribution caused by tunnel excavation. The tunnel section surrounding rock arch roof subsidence, inverted arch uplift; The surrounding rock around the tunnel appears seasonal freeze-thaw circle, and the maximum freezing depth appears at the vault. The maximum percolation velocity occurs at the foot of the sidewall wall, the osmotic pressure surface near the excavation section is dense, the hydraulic slope is large, and the seepage water pressure on the rock mass is high. Because of the shallow buried depth and the double influence of the air temperature on the inner wall of tunnel and the mountain surface, the freezing and thawing ring is extremely serious in the area of arched roof of surrounding rock. Under the action of hydro-thermal coupling, the freezing depth of surrounding rock decreases and the displacement and stress increase. After 10 years of operation, the tunnel surrounding rock arch roof subsidence increased from 0.89 mm to 1.89 mm, and the maximum tensile stress of lining increased from 0.4 MPA to 1.3 MPA. It can be seen that the freeze-thaw cycle has a great influence on the mechanical properties of surrounding rock and lining. In the course of tunnel design and construction in cold region, the effect of frost heaving force must be considered, and the interaction of temperature field, water field and stress field must be taken into account in order to reduce the freeze-thaw disaster of tunnel in cold region. In order to reduce the heat exchange between the air temperature inside and outside the tunnel and surrounding rock, good insulation measures should be taken at the entrance and inner wall of the tunnel. Combined with grouting water plugging, laying waterproof layer, setting drainage side ditch and so on, the heat exchange between inside and outside side of lining can be reduced.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U451.2

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