摘要
任意拉格朗日-欧拉(ALE)方法吸取了拉格朗日和欧拉法的优点,避免了常规有限元中拉格朗日方法的网格畸变问题,适用于开口管桩高频振动贯入过程的计算分析。采用ALE有限元方法,建立开口管桩高频振动贯入过程的数值模型,对沉桩过程中挤土效应、桩侧阻力和土塞效应的变化规律进行了详细研究。研究结果表明:挤土应力主要沿径向传播,且深层土体受到的挤土应力比浅层土体大;水平挤土位移随管桩贯入深度的增加而增大,而最大水平挤土位移与管桩贯入深度存在累积效应;挤土效应的影响范围约为10倍管径,因此在施工过程中要给以足够重视;桩外侧摩阻力随贯入深度增加呈近似线性增长,桩内侧摩阻力随贯入深度增加而呈非线性增长,增长速率随贯入深度增加而逐渐增大;管内土塞处于不完全闭塞状态,土塞程度由完全非闭塞向部分闭塞过渡。此外,研究了土体模量、桩土界面摩擦系数、振动频率和桩径对土体位移的影响。
Arbitrary Lagrangian-Eulerian( ALE) methods couple the advantages of Lagrangian and Eulerian methods,and avoid the mesh distortion problem of Lagrangian method of general finite element. The methods can effectively analyze the penetration process of open-ended pipe piles driven by high frequency hammers. Based on ALE finite element methods,the finite element model of full penetration process of open-ended pipe piles driven by high frequency vibratory hammers is built. The paper studies in detail squeezing effect,frictional resistance and soil plugging effect during pile-sinking. The computational results show that the compacting stress mainly spreads along the horizontal direction,and the compacting stress in deep soil layers is larger than compacting stress in shallow soil layers. The horizontal compacting displacements increase with the increase of penetration depth. But the maximum compacting displacement delays penetration depth. The affecting range of squeezing effect is approximately 10 times pile diameter. So it is necessary to put great emphasis on full penetration process of pipe pile. Outside friction resistance of piles increases linearly with the increase of penetration depth. Inside friction resistance of pilesincreases nonlinear with the increase of penetration depth. The growth rate increases gradually with the increase of penetration depth. Soil plugs of pipes are incompletely plugged conditions. Degree of soil plugs varies from unplugged conditions to partially plugged conditions. Furthermore,the influence of soil elastic modulus,frictions,vibration frequencies and pile diameters on the compacting displacements are investigated.
出处
《工程地质学报》
CSCD
北大核心
2016年第3期398-408,共11页
Journal of Engineering Geology
基金
国家自然科学基金项目(41272299)资助
关键词
开口管桩
高频振动
ALE方法
有限元
Open-ended pipe pile
High frequency vibration
Arbitrary lagrangian-eulerian method
Finite element method
