静压敞口预应力高强混凝土管桩界面剪切性状试验研究

发布时间：2018-04-14 10:08

本文选题：敞口PHC管桩 + 桩土界面　；参考：《建筑结构学报》2017年05期

【摘要】：桩土界面剪切行为对静压敞口预应力高强混凝土(PHC)管桩沉贯性状及长期承载力特性具有至关重要的作用。通过成层土地基中桩身预埋光纤光栅(FBG)传感器的静压桩足尺试验,分别对敞口PHC管桩贯入及静载荷试验中的桩土界面剪切行为进行研究。结果表明:在贯入阶段,桩身轴力及侧摩阻力沿桩的深度方向逐渐传递,传力幅值与桩周土体性状密切相关,土层界面处轴力传递效率依次为98.2%、92.2%、96.3%、83.8%、80.5%。随着压桩循环次数的增加,同一深度土层摩阻力呈逐渐减小趋势。经历5个压桩循环后,深度6 m处的砂质粉土层摩阻力减小幅度约为46.25%,深度10 m处的粉质黏土层经历3个压桩循环后摩阻力减小幅度约为12.1%;载荷试验过程中,桩侧摩阻力随着桩顶荷载施加自上而下逐步发挥。摩阻力完全发挥所需的桩土相对位移,粉质黏土层的最大,约为6.96~7.46 mm,淤泥质黏土层的次之,约为6.05 mm,砂质粉土层的最小,约为4.23 mm;与原状土相比,重塑区土体含水量、孔隙比参数指标降低,重度、黏聚力及内摩擦角增大。桩周重塑区土体物理力学指标变化是贯入及载荷试验阶段桩土界面剪切行为不同的重要原因。
[Abstract]:The shear behavior of pile-soil interface plays an important role in the penetrability and long-term bearing capacity of prestressed high-strength concrete (PHC) piles under static pressure.Based on the full-scale test of pile-embedded fiber Bragg grating (FBG) sensor in layered soil foundation, the pile-soil interface shear behavior of the open PHC pipe pile in the static load test and the penetration test were studied respectively.The results show that the axial force and lateral friction of the pile are gradually transferred along the depth direction of the pile at the penetration stage, and the amplitude of the transmission force is closely related to the soil properties around the pile. The axial force transfer efficiency at the interface of the soil layer is 98.22 / 92.2 / 96.3and 83.8 / 80.5 respectively.With the increase of pile cycle times, the frictional resistance of the same depth soil layer decreases gradually.After five pile cycles, the frictional resistance of sandy silt layer at 6 m depth decreases by 46.25, and the friction resistance of silty clay layer at 10 m depth decreases by about 12.1after three pile cycles.The side friction of pile is exerted gradually from top to bottom with the load on the top of pile.The relative displacement of pile and soil was brought into full play by friction resistance, the maximum of silty clay layer was 6.967.46mm, the second was silt clay layer (6.05 mm), and the minimum of sandy silt layer (4.23 mm), compared with undisturbed soil, the soil water content of remolded area was higher than that of undisturbed soil.The porosity ratio parameter index is decreased, the heavy degree, the cohesion force and the internal friction angle increase.The change of physical and mechanical indexes of soil in the remolded zone around pile is the important reason for the different shear behavior of pile-soil interface in the stage of penetration and load test.
【作者单位】：中国海洋大学工程学院;南洋理工大学土木与环境工程学院;浙江理工大学建筑工程学院;青岛理工大学土木工程学院;
【基金】：国家自然科学基金项目(51408439,41402275) 山东省住房和城乡建设厅科技项目(KY048) 潍坊市科技发展计划项目(2015GX012)
【分类号】：TU473.11

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