浅埋隧道开挖与既有建筑基础荷载相互影响的模型试验和理论计算研究

发布时间：2018-03-25 17:06

本文选题：模型试验　切入点：数值分析　出处：《北京交通大学》2015年博士论文

【摘要】：通过模型试验、理论分析及数值模拟,研究了浅埋隧道开挖与既有建筑基础荷载的相互作用,具体的研究内容和主要成果如下： (1)建立了平面应变模型试验系统,其中包括地层模型、桩基荷载模型、箱基荷载模型、浅埋隧道开挖模型和支护模型,以及桩基荷载或箱基荷载、地层压力、地层沉降、隧道支护应变的量测装置。①进行了一系列地层损失模型试验,分析了地表最大沉降位移及沉降槽宽度参数与地中最大沉降位移及沉降槽宽度参数的函数关系；②针对不同水平、竖直位置的既有桩基荷载进行了一系列隧道开挖模型试验及数值模拟,分析了既有桩基荷载对邻近浅埋隧道开挖引起地层压力重分布、地层沉降及隧道支护内力的影响特征,结果表明：对于桩径和水平相对距离都相同但桩长不同的桩基荷载,桩长与隧道埋深相同时,对隧道开挖效应影响最大；对于桩径和桩长都相同的桩基荷载,对隧道开挖效应的影响程度随桩基中心与隧道轴线水平距离的减小而增大;当桩基中心与隧道轴线水平距离和隧道直径比值介于0.5-4时,桩基荷载对隧道开挖效应影响较大；③针对不同水平、竖向位置的既有箱基荷载进行了一系列隧道开挖模型试验及数值模拟,结果表明：水平距离、箱基荷载都相同但埋深不同的箱基,对隧道开挖效应的影响程度随着箱基埋深的增加而增大,当箱底埋置深度超过隧道拱顶时,对隧道开挖效应的影响程度随箱基埋深的增加而减小；箱基埋置深度相同但水平距离不同,对隧道开挖效应的影响程度随箱基边缘与隧道轴线水平距离的减小而增大,当箱基边缘与隧道轴线水平距离和隧道直径比值介于0.5-4.0时,箱基荷载对隧道开挖效应的影响较大； (2)建立了地层损失的时间函数模型,结合萨格塞塔解,给出了预测浅埋隧道开挖引起地表沉降随时间及施工参数变化的数学表达式,通过等效简化模型,推导了隧道全断面开挖、台阶法开挖及其它分部开挖引起地层位移的解析表达式,计算分析了自由地层及承载地层开挖速度、台阶间距、施工工序及地表沉降速度系数对地表沉降的影响特征； (3)提出了建筑基础荷载地层承载区的概念,推导了桩基荷载和箱基荷载地层的位移场；应用沃卢杰-布克位移解,分析了隧道开挖对桩基或箱基地层承载区的影响；通过数值模拟,分析了隧道中心与建筑基础荷载的水平距离、隧道埋深、隧道开挖半径及隧道开挖进度对建筑基础地层承载区的影响特征,结果表明：通过改变隧道施工参数,建筑基础地层承载区的形状与范围在隧道的开挖方向、水平方向及竖直方向都有不同程度的变化。而这些变化规律的得出,将对隧道的设计与施工具有指导意义。
[Abstract]:Through model test, theoretical analysis and numerical simulation, the interaction between excavation of shallow tunnel and load of existing building foundation is studied. The specific research contents and main results are as follows:. 1) the plane strain model test system is established, which includes stratum model, pile foundation load model, box foundation load model, shallow tunnel excavation model and support model, pile foundation load or box foundation load, formation pressure, stratum settlement. A series of model tests of ground loss are carried out by measuring the strain of tunnel support. The function relationship between the maximum subsidence displacement and the width parameter of the settlement trough and the maximum settlement displacement and the width parameter of the settlement trough in the ground is analyzed. 2 the relationship between the maximum settlement displacement and the width parameter of the settlement trough in the ground is analyzed according to different levels. A series of tunnel excavation model tests and numerical simulation are carried out on the existing pile foundation load in vertical position. The influence characteristics of the existing pile foundation load on the formation pressure redistribution, stratum settlement and tunnel support internal force caused by the excavation of the adjacent shallow tunnel are analyzed. The results show that for the pile with the same diameter and horizontal distance but different pile length, when the length of pile is the same as the depth of tunnel, the effect of tunnel excavation is the biggest, and the load of pile with the same diameter and length of pile is the most important. The degree of influence on tunnel excavation effect increases with the decrease of horizontal distance between the center of pile foundation and the axis of tunnel, and when the horizontal distance between the center of pile foundation and the axis of tunnel and the ratio of tunnel diameter are between 0.5-4, Pile foundation load has great influence on tunnel excavation effect. A series of tunnel excavation model tests and numerical simulations have been carried out for the existing box foundation loads at different levels and vertical positions. The results show that the horizontal distance is different. The influence of the box foundation with the same load but different buried depth on the excavation effect increases with the increase of the burying depth of the box foundation. When the buried depth of the bottom of the box exceeds the vault of the tunnel, The influence degree of the tunnel excavation effect decreases with the increase of the buried depth of the box foundation, and the influence degree on the tunnel excavation effect increases with the decrease of horizontal distance between the box foundation edge and the tunnel axis, but the horizontal distance of the box foundation is the same as the horizontal distance between the box foundation and the tunnel axis. When the horizontal distance between box foundation edge and tunnel axis and the ratio of tunnel diameter are between 0.5-4.0, the influence of box foundation load on tunnel excavation effect is greater. (2) the time function model of formation loss is established, and the mathematical expression for predicting the variation of surface subsidence with time and construction parameters caused by shallow tunnel excavation is given, and the equivalent simplified model is given. The analytical expressions of stratum displacement caused by full section excavation, step method excavation and other partial excavation are derived, and the excavation velocity and step spacing of free and bearing strata are calculated and analyzed. The characteristics of the influence of the construction procedure and the coefficient of the surface settlement velocity on the surface settlement; (3) the concept of load-bearing zone of building foundation is put forward, the displacement field of pile foundation and box foundation is deduced, and the influence of tunnel excavation on the bearing zone of pile foundation or box base layer is analyzed by using Voluget-Buke displacement solution. Through numerical simulation, the influence characteristics of the horizontal distance between the tunnel center and the building foundation load, the tunnel burial depth, the tunnel excavation radius and the tunnel excavation schedule on the bearing zone of the building foundation are analyzed. The results show that the tunnel construction parameters are changed. The shape and range of the bearing area of the stratum of building foundation have varying degrees in the excavation direction, horizontal direction and vertical direction of the tunnel, and the conclusion of these changing rules will be of guiding significance to the design and construction of the tunnel.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U452;TU470

【参考文献】