【作者】 王东阳；

【导师】 谢永利；

【作者基本信息】 长安大学 ， 道路与铁道工程， 2006， 博士

【摘要】 本文通过对松花江流域特大桥设计与施工存在问题的分析，以及对特大桥桩基承载能力的试验研究，分析了用不同试验方法确定桩基承载能力的适用性和局限性，从技术和经济的角度，提出了用模拟试验法确定桩基承载力的新方法。 模拟试验法是以经典的莫尔—库伦强度准则为理论基础提出确定桩侧摩阻力的剪切试验，该试验在设计过程中综合考虑了地层环境、成桩工艺、实际地层压力等各项因素的影响，在加荷设计过程中考虑了岩土体自重应力作用以及桩在极限荷载作用下的不同承载性状，分别测定不同地层岩性在荷载作用下的剪应力和水平位移，作出剪切应力-剪位移曲线图。求得不同地层与桩身之间的侧摩阻力。桩端承载力以三轴压缩试验为模型模拟桩端地层的承载性能，以一定倍数折减的围压分别作用于多个试样上，根据侧向围压及试样的三轴抗压强度绘制摩尔应力圆，求出摩尔强度包线，从而依据实际桩端地层所受的侧向应力在此包线上求得其三轴抗压强度，求出桩端极限承载力。 相似性问题在模拟试验确定桩基承载力中得到充分体现，包括试验与工程桩所处环境的相似性，确定桩侧摩阻力的剪切试验相似模拟以及确定桩端承载力的三轴试验相似模拟等三个方面。同时提出三种确定单桩极限承载力的方法，以桩土间相互作用的法向应力三种取值方法为基础，同时考虑了桩周岩土体屈服强度的影响，分别以自重引起的侧向应力、有限元数值计算产生的法向应力、自重与有限元耦合产生的法向应力计算出三种极限承载力，并提出与现场实测的对比研究模拟试验确定单桩极限承载力的准确性。模拟试验法具有传统测桩方法难以实现的优点：可方便的计算出各种情况的桩基承载力值，如考虑冲刷线的深度、桩不同埋深时的承载力值；试验周期较短，试验费用较少，可以达到较高的精度，能够为大型桩基工程建设特别是大型桥梁工程的设计与施工提供科学依据，具有广泛的应用前景。更多还原

【Abstract】 According to the existed question analysis on SongHua river the largest bridge. And test study for its basic carry capacity. Analysis applicability and localization for different test method decide pile carry capacity. Form technique and economic ,advanced new method for simulation testing to decide pile carrying capacity.Simulation testing method is with the classical Mol-Coulomb intensity guide to bring forward to make sure pile lateral friction bigger cut testing. The testing design colligation considered stratum circumstance, made-pile arts, fact stratum compressive stress so on each factor affect, in design considered rock and soil self-stress action and pile on limit load different carrying capacity, separate determine different stratum rock shearing strength and horizontal displacement, plotting shearing strength-shearing displacement curve. Gained different stratum from pile lateral friction. The pile tip carrying capacity with triaxial compress testing model simulate pile tip stratum carrying capacity. With certain multiple discount compressive action multi-pile, base on lateral compressive and sample triaxial compress intensity plotting Mol-stress circle, obtain Mol-intensity curve, then depend on fact pile tip stratum lateral stress gain triaxial compressive intensity from curve, obtain pile tip limit carrying capacity.Comparability problem gained sufficiency embodiment in simulation testing determine pile carrying capacity, including testing and pile condition comparability, determine pile lateral friction.Cut test resemble simulate and determine pile tip carrying capacity triaxial test resemble so on three aspect. At the same time advanced three kinds to determine single pile limit carrying capacity method, base on pile among soil interaction stress three kinds to take value method, at the same time, considered pile around rock-soil tensile intensity effect, leave each other self-weight bring lateral stress , finite element evaluation produce stress, self-weight and finite element coincidence bring stress to account three kinds limit carrying capacity ,and put forward to parallel to locale study simulate test to determine single pile limit carrying capacity veracity. Simulate test methods have more excellence than tradition measure pile method.: may convenience calculate all kinds of conditions pile foot carrying capacity. If consider wash out line depth., pile vary burying depth bear the weight of force. Test periods short, test cost little , economy with reason, may receive high precision, it is capable of larger pile foundation engineering construction especially larger bridge engineering design and construction provide science bases, possess abroad application foreground.更多还原