泥皮强度对钻孔灌注桩自平衡检测的影响研究

发布时间：2018-07-21 10:01

【摘要】：随着建设行业的迅猛发展,由于钻孔灌注桩基具有承载能力高、施工方便以及造价低的优点逐渐成为主要的基础形式,但受到施工工艺和技术水平的限制,这也导致了桩基础中普遍存在难以清除的桩周泥皮。由于泥皮存在对桩承载力影响很大,因此分析泥皮强度对桩承载性状的影响具有非常重要的实用价值。由于自平衡测桩法能解决传统测桩基承载力检测方法中存在的种种问题,因而在土木工程领域有广泛的应用。本文结合自平衡测桩的方法研究了泥皮强度对桩承载力的影响。本文在前人研究的基础上,运用理论分析和有限元数值模拟的方法,系统研究了桩周泥皮在自平衡测桩下对承载性状的影响。本文主要工作及研究成果如下:1.本文对湖南省常德市一工程实例进行了桩的自平衡现场监测分析。结果表明:58天自平衡的检测结果与28天的结果相比,承载力提高了10.6%。2.建立桩-泥皮-土相互作用的ABAQUS有限元模型。通过折减桩—土接触面系数来模拟泥皮强度的变化,以此来模拟桩周泥皮随时间的变化,分析了泥皮强度变化对钻孔灌注桩自平衡检测下竖向极限承载力的影响。3.通过分析荷载与位移、桩侧摩阻力、轴力等物理量的关系,得出了泥皮桩的承载机理及泥皮强度变化对承载力的影响,结果表明:随着桩-土接触面折减系数(泥皮强度)的增大,桩身滑动的临界荷载也随之增大;另外在相同荷载下,随着折减系数的增大,桩-土接触面的极限摩阻力也随之增加,而桩身位移随之减小。4.分析桩-土接触面折减系数的变化与桩承载性能的关系,结果表明:折减系数与承载力的变化并非线性关系,随着折减系数的增加,极限摩阻力、极限端阻力和极限承载力的增量逐渐减小。
[Abstract]:With the rapid development of construction industry, because of the advantages of high bearing capacity, easy construction and low cost, bored cast-in-place pile foundation has gradually become the main basic form, but is limited by construction technology and technical level. This also leads to the widespread existence of pile surrounding mud skin which is difficult to remove in pile foundation. Because the existence of mud has great influence on the bearing capacity of pile, it is of great practical value to analyze the influence of the strength of mud skin on the bearing capacity of pile. The self-balanced pile testing method can solve the problems existing in the traditional pile foundation bearing capacity testing method, so it has been widely used in the field of civil engineering. In this paper, the influence of mud skin strength on pile bearing capacity is studied by using self-balanced pile measurement method. Based on the previous studies, the influence of the mud skin around the pile on the bearing behavior of the self-balanced pile is systematically studied by using the theoretical analysis and the finite element numerical simulation method. The main work and research results of this paper are as follows: 1. In this paper, a project case in Changde City, Hunan Province, is analyzed by self-balanced field monitoring. The results show that the bearing capacity of the 58 days' self-equilibrium test is 10.60.2. higher than that of the 28-day 's. The Abaqus finite element model of pile-mud-soil interaction is established. The change of mud crust strength is simulated by reducing the coefficient of pile-soil contact surface to simulate the change of mud crust around pile with time. The influence of the change of mud crust strength on the vertical ultimate bearing capacity of bored pile under self-balance test is analyzed. By analyzing the relationship between load and displacement, pile side friction, axial force, the bearing mechanism of mud pile and the influence of the change of mud skin strength on the bearing capacity are obtained. The results show that the critical load of pile sliding increases with the increase of the reduction coefficient of pile-soil contact surface (mud skin strength), and with the increase of the reduction coefficient under the same load, The ultimate frictional resistance of the pile-soil interface also increases, and the displacement of the pile body decreases by .4. The relationship between the variation of the reduction coefficient of the pile-soil interface and the bearing capacity of the pile is analyzed. The results show that the change of the reduction coefficient and the bearing capacity is not linear, and with the increase of the reduction coefficient, the ultimate frictional resistance is not linear. The increment of ultimate end resistance and ultimate bearing capacity gradually decreases.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU473.1

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