深基坑开挖对坑外深层土体及邻近隧道的影响研究

发布时间：2018-04-30 12:58

本文选题：深基坑 + 深层土体　；参考：《天津大学》2014年博士论文

【摘要】：本文通过对某深基坑开挖全过程中围护桩的水平位移进行实测，发现由于水平支撑提供的支撑刚度不同，并受到基坑非对称性的影响，不同位置处的围护桩可产生不同的水平位移分布模式，，且最大水平位移值也存在明显差别。通过建立精细化有限元模型，针对4种典型围护结构变形模式引起的坑外深层土体位移场变化特点进行分析，结果表明，即使围护结构最大水平位移相同，由于侧移分布模式不同，基坑外深层土体的位移场可存在较大差别，从而可能对环境产生不同程度的影响。围护结构在内凸型和复合型模式下，坑外深层土体竖向变形可分为凹槽形沉降区、三角形过渡区和隆起区，悬臂型模式则只存在三角形变形区和隆起区，而踢脚型模式下凹槽形沉降区影响范围更深；对于内凸型和复合型模式，坑外深层土体水平位移场可分为弓形变形区、变形过渡区以及悬臂形变形区，悬臂型模式导致坑外水平位移全部呈悬臂形，踢脚型模式下影响区的范围更深且更广。进而探讨了不同围护结构变形模式引起坑外既有隧道变形及受力的变化特性，并结合隧道位移的控制标准，分析4种模式下隧道产生过大位移的坑外范围，并将不同模式下的位移影响范围进行了对比。根据拱顶拱底的竖向变形特点，可将隧道变形按深度分为沉降区、变形过渡区及隆起区。复合型与内凸型模式下各区域的范围及特点基本相同；悬臂型模式对坑外隧道竖向位移影响较弱，沉降区范围明显减小；踢脚型模式中坑外的沉降区域增大，变形过渡区及隆起区范围被显著压缩。悬臂型模式对坑外隧道的位移影响范围最小，内凸型与复合型模式下范围基本相同，分布大于悬臂型，而踢脚型模式下范围最大。在实际工程中除控制围护结构最大变形值外，尚应根据周围环境特点合理控制围护结构变形模式，并尽可能避免出现踢脚模式变形。
[Abstract]:By measuring the horizontal displacement of the retaining pile during the excavation of a deep foundation pit, it is found that the stiffness of the support provided by the horizontal bracing is different and affected by the asymmetry of the foundation pit. Different horizontal displacement distribution patterns can be produced in different positions of retaining piles, and the maximum horizontal displacement values are obviously different. By establishing a fine finite element model, the variation characteristics of the displacement field of deep soil in the deep layer outside the pit caused by the deformation modes of four typical enclosure structures are analyzed. The results show that the maximum horizontal displacement of the enclosure structure is the same, even if the maximum horizontal displacement of the enclosure structure is the same. Because of the different lateral distribution patterns, the displacement field of the deep soil outside the foundation pit can be greatly different, which may have a different degree of impact on the environment. The vertical deformation of deep soil outside the pit can be divided into concave settlement zone, triangular transition zone and uplift zone, while the cantilever model only exists triangular deformation zone and uplift zone. For the convex and composite models, the horizontal displacement field of deep soil can be divided into the arch deformation zone, the deformation transition zone and the cantilever deformation zone. The cantilever mode causes the horizontal displacement of the pit to be all cantilever, and the area of influence is deeper and wider under the kick-foot mode. Furthermore, the characteristics of deformation and force change of existing tunnel outside the pit caused by different deformation modes of enclosure structure are discussed. Combined with the control standard of tunnel displacement, the out-of-pit range of excessive displacement of tunnel under four modes is analyzed. The influence range of displacement in different modes is compared. According to the vertical deformation characteristics of arch bottom, tunnel deformation can be divided into settlement zone, deformation transition area and uplift area according to depth. The range and characteristics of each region are basically the same in the composite and convex mode, the influence of cantilever mode on the vertical displacement of the tunnel outside the pit is weak, and the settlement area is obviously reduced, while the settlement area outside the pit increases in the kick foot mode. The range of the deformation transition zone and the uplift area is significantly reduced. The cantilever mode has the smallest influence range on the displacement of the tunnel outside the pit. The range of the convex type is basically the same as that of the compound mode, and the distribution is larger than that of the cantilever type, while the range of the kicking mode is the largest. Besides controlling the maximum deformation value of the enclosure structure, the deformation mode of the surrounding structure should be reasonably controlled according to the characteristics of the surrounding environment, and the deformation of the kick foot mode should be avoided as far as possible in the actual engineering.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU753;U452.1

【参考文献】