桥梁基础中混凝土扩盘桩破坏模式及极限承载力研究

发布时间：2018-04-03 15:42

本文选题：混凝土扩盘桩　切入点：破坏模式　出处：《吉林大学》2014年博士论文

【摘要】：近年来随着国家经济建设的快速发展，桥梁、地下空间、高层超高层建筑等工程项目的数量与规模急剧增加，建设标准日趋严格，对桩基技术的研究与应用也提出了更高的要求。本论文全面介绍了混凝土扩盘桩的发展现状，国内、外的研究结果表明：混凝土扩盘桩具有单桩承载力高、节约材料、沉降量小、设计灵活、施工操作简便，适用区域广等诸多方面的优点。由于混凝土扩盘桩自身特点所具有的潜在的、巨大的经济价值和社会效益，使其得到了行业内越来越广泛的重视，展现出了强大生命力和发展前途，也使其成为桩基技术领域内的研究热点之一。目前，混凝土扩盘桩的成桩工艺虽然得到了迅速的发展，但针对混凝土扩盘桩作用机理的研究成果相对较少，尚未形成完整的研究体系，因此限制了该型桩的推广应用。为了进一步完善混凝土扩盘桩技术的理论基础，本论文在现有研究成果的基础上，对混凝土扩盘桩在竖向压力和拉力作用下的桩土共同工作机理、桩周及盘上下土体的破坏状态等方面进行了深入的理论分析和试验研究。本论文采用有限单元法，应用ANSYS软件建立了大量的分析模型，定性地分析了混凝土扩盘桩的位移、应变、应力等变化趋势，确定了盘径、盘坡度及盘间距对破坏状态的影响，并通过独创的半面桩小模型试验和现场大比例实桩试验对理论分析结果进行了验证，得出了桩侧摩阻力有效长度的计算方法，进而确定了混凝土扩盘桩单桩抗压、抗拔极限承载力的计算模式。本论文研究成果完善了混凝土扩盘桩基础理论。通过对混凝土扩盘桩在竖向压力和拉力作用下盘上和盘下土体破坏状态分析，，提出了桩侧摩阻力有效长度的概念，并应用新的理论得出承力扩大盘盘端土体承载力计算方法，从而修正了现有的单桩承载力计算中的不合理部分。本研究提出的单桩极限承载力计算方法更符合工程实际，为混凝土扩盘桩基础设计提供了可靠的理论依据，完善了混凝土扩盘桩基础理论的研究，为进一步推进该技术的广泛应用奠定了坚实的理论基础。
[Abstract]:In recent years, with the rapid development of national economic construction, the number and scale of engineering projects such as bridges, underground space, high-rise and super high-rise buildings have increased dramatically, and the construction standards have become more and more stringent.Higher requirements for the research and application of pile foundation technology are also put forward.In this paper, the development status of concrete expanded disc pile is introduced comprehensively. The results of domestic and external research show that concrete expanded plate pile has high bearing capacity, saving material, small settlement, flexible design and simple construction operation.Applicable to a wide range of advantages in many areas.Because of the potential, huge economic value and social benefit of the concrete pile with its own characteristics, it has been paid more and more attention to in the industry, showing its strong vitality and development prospects.It has also become one of the research hotspots in the field of pile foundation technology.At present, although the pile forming technology of concrete expanded disc pile has been developed rapidly, the research results on the action mechanism of concrete expanded disc pile are relatively few, and the complete research system has not been formed, so the popularization and application of this type of pile is limited.In order to further improve the theoretical basis of concrete pile expansion technology, this paper, on the basis of the existing research results, works together on the pile-soil mechanism of concrete expanded disc pile under vertical pressure and tensile force.The failure state of the soil around the pile and the top and bottom of the pile is analyzed theoretically and experimentally.In this paper, the finite element method and ANSYS software are used to establish a large number of analysis models. The change trends of displacement, strain and stress of concrete pile are analyzed qualitatively, and the influence of the diameter, slope and spacing of the plate on the failure state is determined.The theoretical analysis results are verified by the original half plane pile small model test and the field large scale real pile test, and the calculation method of the effective length of pile side friction is obtained, and then the compressive resistance of concrete expanded disc pile single pile is determined.The calculation model of ultimate bearing capacity of pullout.The research results of this paper have improved the basic theory of concrete pile.Based on the analysis of the failure state of the upper and lower soil mass under the action of vertical pressure and tensile force, the concept of effective length of friction on the side of the pile is put forward, and the method of calculating the bearing capacity of the soil bearing force at the end of the disc is obtained by applying the new theory.Thus, the unreasonable part of the existing calculation of bearing capacity of single pile is corrected.The calculation method of the ultimate bearing capacity of single pile in this study is more in line with the engineering practice, which provides a reliable theoretical basis for the design of concrete pile foundation, and improves the research on the basic theory of concrete pile.It lays a solid theoretical foundation for further promoting the wide application of this technology.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U443.1

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