【作者】 刘妮；

【导师】 马建林；

【作者基本信息】 西南交通大学 ， 岩土工程， 2013， 硕士

【摘要】 超长大直径钢管桩由于单桩承载力较高、抗弯能力良好、沉桩工艺简单、对土体扰动小而越来越广泛地应用于跨海大桥的桩基础中。钢管桩由钢管和内填的核心钢筋混凝土组成,其基本原理是利用钢管对核心混凝土产生的套箍约束作用,使核心混凝土处于三向受压状态,从而使核心混凝土具有更高的抗压强度和压缩变形能力,同时钢管也具有较强的承载力,二者结合得到的钢管桩具有较强的刚度。然而关于大直径钢管桩的研究仍十分不足,尤其是考虑承台、群桩效应及土体等因素的影响下钢管桩在压-弯-剪荷载作用下的受力特性基本没有研究资料。针对这一现状,本文依托港珠澳跨海大桥桩基础工程,结合局部桩基模型试验、原型桩基数值模拟分析及理论计算等方法对比分析在压-弯-剪荷载作用下桩基原型中钢管桩的受力性能,得到以下结论：(1)钢管桩竖向变形随着轴力增加而线性增大；水平位移随着剪力和弯矩的增大而呈线性增大,并且桩顶水平位移最大、桩端水平位移最小；原型桩基中6根钢管桩竖向变形和水平变形一致,但中桩受力约为角桩的1.3倍；(2)轴线1处上端纵向压应变随工作荷载增加而增大、下端纵向压应变随工作荷载增加而减小,轴线3处上端纵向压应变随工作荷载增加而减小、下端纵向压应变随工作荷载增加而增大,轴线2处压应变沿桩身分布均匀、随工作荷载增加略微减小；总体上中桩纵向应变比角桩大约9%；(3)本文中的压-弯-剪荷载作用下钢管应变大于核心混凝土,不符合平截面变形情况；(4)钢管与核心混凝土应力比沿桩身均匀分布,应力比大小约为6左右,则钢管桩中钢管和核心混凝土的竖向荷载分担比约为1：3；(5)由于原型桩基是端承式桩基础,中桩与角桩的侧摩阻力分布及大小基本相同；而中桩端阻力大于角桩、第一排桩端阻力大于第二排桩；(6)局部桩基模型试验中单根钢管桩和原型桩基数值模拟中的中桩和角桩在压-弯-剪荷载作用下的竖向变形、水平变形及各轴线、各截面的纵向应变分布规律均一致,但相同条件下原型桩基中钢管桩的竖向变形、水平变形和纵向应变要小于局部桩基,其变形和应变的变化也更加规律、稳定。更多还原

【Abstract】 The super-long and large diameter steel pipe piles are widely used in bridge pile foundation, because of the high bearing capacity, good flexural capacity, simple process and small soil disturbance. The steel pipe pile is composed of steel tube and core concrete filling in it. Its basic principle is the confinement effect on the core concrete made by steel tube, so that the core concrete is in the three state compression. The core concrete has high compressive strength and compressive deformation ability, and the steel tube has high carrying capacity, so that the combination of them has strong stiffness. However, research on the large diameter steel pipe pile is still very insufficient, especially the research of steel pipe pile in the pressure-bending-shear loads considering the influence of pile cap, the pile group effect and soil factors.In view of this situation, this paper relies on the Hong Kong-Zhuhai-Macao Bridge Pile Foundation Engineering, combined with the model test of part foundation, the numerical simulation of prototype pile and calculation analysis to make comparison and analysis of prototype pile’s mechanical characteristics in the pressure-bending-shear loads, and obtained the following conclusions:(1) the vertical deformation increased linearly with the axial force; horizontal displacement increased linearly with the shearing force and moment, and the maximum horizontal displacement is in the top of the pile, the minimum one is in the bottom of pile; the vertical and horizontal deformation of this six steel pipe piles in the foundation are consistent, but the stress of the middle piles are about1.3times than the corner piles;(2) The compressive strain in axis one increases at the upper and reduce at the bottom with the increase of work load, the compressive strain in axis three is in contrast with axis one, the compressive strain in axis two slightly decreased with the increase of work load; on the whole strain of the middle piles are9%greater than the corner piles;(3) The compressive strain of steel tubes are greater than the core concrete, it doesn’t accord with flat section deformation assumption;(4) The stress ratio of the steel tube and the core concrete is about6, so that the vertical load ratio of the steel tube and the core concrete is about1:3;(5) Because the prototype pile foundation is end bearing pile foundation, so that the pile side friction of the middle piles and the corner piles are basically the same; the resistance in the bottom of the middle piles are greater than the corner piles, and the resistance in the first row is greater than the second;(6) The vertical deformation、horizontal deformation and longitudinal strain of the part pile foundation model test and the prototype pile foundation in the numerical simulation are consistent in the pressure-bending-shear loads. But the deformation and strain in the prototype pile foundation are less and more stable than the one in the part pile foundation.更多还原