采煤沉陷区框架桥旁侧堆载地基加固机理研究

发布时间：2018-01-10 12:05

本文关键词：采煤沉陷区框架桥旁侧堆载地基加固机理研究　出处：《中国矿业大学》2014年硕士论文　论文类型：学位论文

【摘要】：淮南矿业集团谢桥煤矿济河铁路中桥，受煤层群开采的影响，桥基地表沉陷量巨大，仅竖直方向的沉陷已超过10m。由于桥梁上部结构加高，地基承载力不满足要求，，该桥已经进行过一次高压旋喷桩地基处理，常规既有建（构）筑物地基加固方法很难再次适用。在这种背景下本文提出将旁侧堆载加固方法应用到采煤沉陷区桥梁地基的加固治理中，开展了天然地基和既有复合地基旁侧堆载加固机理研究。以FLAC3D数值计算和假定滑移面法理论分析为研究手段，分析了堆载参数对地基极限承载力的影响规律，给出了地表超载和地基承载力增量的近似关系式；通过理论推导，给出地基承载力增量计算公式，为采煤沉陷区桥梁地基堆载设计提供一定理论基础。本文首先通过数值模型试验，分析了天然地基和既有复合地基堆载加固时地基承载力变化规律。通过改变天然地基煤矸石堆载体尺寸及位置参数，经分析得出高度是影响加固效果的主要因素的结论。在堆载高度H1≤6m时，高度与地基承载力增量近似为线性关系；通过改变堆载体物理力学参数，经分析得出填料容重是影响加固效果的主要因素的结论，容重与地基承载力增量近似为线性关系。根据天然地基研究成果，在既有复合地基堆载法的研究中，仅考虑了堆载高度和填料容重两个可变因素，得到地表堆载量与地基承载力提升幅度之间的近似关系式。其次采用假定滑移面法，对天然地基和既有复合地基，在考虑堆载情况下地基承载力增量进行理论推导，并与数值计算成果对比，分析差异。对于采煤沉陷区天然地基堆载后地基承载力增量Δf a的确定可参照《建筑地基基础设计规范》，考虑采动影响，地基土物理力学参数取采动后的降低值，得到的堆载后地基承载力特征值增量Δf a计算公式，式中堆载极限高度H1=6m；本文根据复合双层地基理论，推导地表超载作用下地基极限承载力增量Δp a的基本表达式，式中堆载极限高度H1=6m，考虑采动影响，地基土物理力学参数取采动后的降低值。最后根据上述研究成果，将旁侧堆载法应用于淮南矿区济河桥加固设计中。堆载后加固区地基承载力提升近5.4%，而下卧层地基承载力提升约14.9%，堆载法将应用于淮南矿区地基处理。
[Abstract]:Huainan Mining Group Corporation Ltd Ji river railway bridge, affected by coal mining, surface subsidence huge bridge base, only vertical subsidence has been more than 10m. because of the upper structure of the bridge height, does not meet the requirements of the bearing capacity of the foundation, the bridge has been a high pressure jet grouting pile foundation treatment, the conventional building is (structure) building foundation reinforcement method is difficult to apply again. In this context this paper will reinforce the governance side loading reinforcement method applied to coal mining subsidence area of bridge foundation, the natural foundation and the both side pile composite foundation load calculation and reinforcement mechanism study. Analysis of slip surface method assumes that the theory research method with FLAC3D values, analyze the influence law of loading parameters on ultimate bearing capacity of foundation, gives the ground overload and bearing the approximate relation of stress increment; through theoretical derivation, increase the bearing capacity of foundation are given The calculation formula provides a theoretical basis for the load design of the bridge foundation in the coal mining subsidence area.
Firstly, the numerical model tests, analysis of the existing natural foundation and foundation bearing capacity variation of composite foundation pile load reinforcement. By changing the natural foundation of the coal gangue carrier size and position parameters obtained by the analysis are the main factors that influence the height of the strengthening effect of knot theory. In the stacking height of H1 = 6m, height with the increment of bearing capacity is approximately linear; by changing the physical and mechanical parameters of pile carrier, through the analysis of filler bulk density is the main factor affecting the reinforcement effect of the conclusion, approximately linear relation between the bearing capacity of foundation. According to the increment of density and natural foundation in the existing research results, the composite foundation pile load research method, considering only the the stacking height and packing density of two variable factors, get the surface load and pile foundation bearing capacity to enhance the approximate relation between the amplitude.
Secondly it is assumed that the sliding surface method is used for both natural foundation and composite foundation, considering the loading condition of foundation bearing capacity increment theory, and the numerical calculation results, analysis of the differences. For the pile bearing capacity increment f a can refer to < code of building foundation design foundation on natural area > the foundation of coal mining subsidence, mining influence, foundation soil physical parameters to decrease the dynamic value of value increment f a formula to calculate the bearing capacity of the pile foundation load characteristics, type loading height limit of H1=6m; according to the theory of compound two-layer foundation, bearing a basic expression force increment P limit ground surface is under overload, load limit height of H1=6m pile type, mining influence, foundation soil physical parameters to decrease the value after the move.
Based on the above results, the loading method is applied to the side of Huainan mining area economy river bridge design. After loading reinforcement foundation bearing capacity of nearly 5.4%, while the underlying layer of foundation bearing capacity increases about 14.9%, loading method applied in Huainan mining area ground treatment.

【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U443.17;U448.14

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