隧道施工对既有群桩的影响研究

发布时间：2018-04-22 16:02

本文选题：隧道开挖 + 群桩　；参考：《广西大学》2015年硕士论文

【摘要】：由于地铁隧道多修建在建筑结构集中的市区,并且城市建筑基础大多采用桩基形式,则地铁隧道施工会不可避免的接近或穿越既有建筑物,引起地层损失和地应力变化,产生地面变形及桩基的附加轴力和附加弯矩,使桩基发生变形和产生沉降力,降低了周围既有桩基的承载能力。本文在现有的研究基础上,首先通过离心模型试验分别研究了广西南宁地区单隧道和双隧道施工对既有群桩的影响,接着对离心试验进行了数值分析,对二者的结果进行了相互验证。然后,基于已经验证的数值模型进一步分析不同埋置深度的单隧道和双隧道施工对临近群桩的地表竖向位移、桩身附加变形、桩身附加弯矩和附加轴力的影响规律。通过研究可得到如下的结论：(1)隧道在不同埋深时开挖引起的地表竖向位移影响规律相似,地表沉降最大值在隧道中心的正上方取得；(2)隧道开挖过程中,桩顶沉降随着隧道开挖的进行而逐渐增加,且隧道的分步开挖会导致承台倾斜,从而引起桩基的内力重分布；(3)当隧道埋深大于等于群桩埋深时,隧道开挖引起的邻近桩基受力形式表现为悬臂梁模式,当隧道埋深小于群桩埋深时,隧道开挖引起的邻近桩基受力形式表现为两端铰支的简支梁模式。隧道埋深越深,群桩受隧道开挖的影响越小；(4)双隧道开挖完成后,无论隧道埋置的深浅,前桩的附加轴力均表现为正值,桩身轴力增加。隧道轴线埋深小于等于桩的埋深时,后桩的附加轴力均表现为正值,桩身轴力增加,隧道轴线埋深大于桩的埋深时,后桩所受到的附加轴力为负值,桩身轴力减少。本文研究成果可为广西地区临近建筑物隧道的设计和施工提供相应的理论指导,从而使其具有实际意义。
[Abstract]:Because the subway tunnel is built mostly in the urban area where the building structure is concentrated, and the urban building foundation is mostly in the form of pile foundation, the subway tunnel construction will inevitably approach or pass through the existing building, which will cause the ground loss and the change of ground stress. The deformation of the ground and the additional axial force and bending moment of the pile foundation result in the deformation and settlement of the pile foundation and reduce the bearing capacity of the existing pile foundation around the pile foundation. On the basis of existing research, the influence of single tunnel construction and double tunnel construction on existing pile groups in Nanning region of Guangxi is studied by centrifugal model test, and then the numerical analysis of centrifugal test is carried out. The results are verified by each other. Then, based on the verified numerical model, the effects of single and double tunnel construction with different buried depths on the surface vertical displacement, additional deformation of pile body, additional bending moment and additional axial force of pile body are further analyzed. The following conclusions can be drawn from the study: the vertical displacement caused by tunnel excavation at different burial depths is similar, and the maximum surface subsidence is obtained at the top of the tunnel center. The settlement of the pile top increases gradually with the excavation of the tunnel, and the gradual excavation of the tunnel will lead to the inclination of the pile cap, thus causing the redistribution of the internal force of the pile foundation. (3) when the buried depth of the tunnel is greater than or equal to the buried depth of the pile group, The stress form of adjacent pile foundation caused by tunnel excavation is cantilever beam mode. When the buried depth of tunnel is less than that of pile group, the force form of adjacent pile foundation caused by tunnel excavation is simply supported beam mode with two ends hinged. The deeper the tunnel is, the less the pile group is affected by the tunnel excavation. After the double tunnel excavation is completed, no matter the depth of the tunnel is shallow, the additional axial force of the front pile is positive, and the axial force of the pile body increases. When the buried depth of the tunnel axis is less than or equal to that of the pile, the additional axial force of the rear pile is positive, and the axial force of the pile body increases. When the buried depth of the tunnel axis line is greater than the buried depth of the pile, the additional axial force of the rear pile is negative and the axial force of the pile body decreases. The research results of this paper can provide corresponding theoretical guidance for the design and construction of adjacent building tunnels in Guangxi area, thus making it of practical significance.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU473.1;U456.3

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