基于桩土相互作用的桩体自沉及屈曲稳定性研究

海洋工程中的钢管桩直径大、桩壁薄、设计长度较长,使用的打桩锤质量大、能量高。在打桩施工中的置锤瞬态过程,须要确定桩身位于泥面以上的自由站立长度及对其进行稳定性分析。结合海洋工程设计实例,应用欧拉-拉格朗日联合分析法(CEL法),对大直径钢管桩在自重及打桩锤静力作用下的下沉过程进行模拟。提出了在给定地基土质条件下确定桩体自沉深度的方法。应用改进的Riks法,考虑桩身变形的几何非线性与桩土相互作用,建立了桩土三维有限元模型,结合实际工程分析桩身的屈曲稳定性。

Study on Pile Self-Penetration and Buckling Stability Considering Interaction between Pile and Subsoil

With the exploitation of oil and gas from shallow sea to deep sea,extra-long deep-penetration pipe piles with large diameter and relatively small wall thickness has been widely used in ocean engineering.Accordingly,heavy driving hammers have to be adopted.The length and the stability of pile stick-up,which is an important part in pile foundation design,are investigated.A practical engineering project has been analyzed.A three dimensional finite element model for pile and soil is established.Analytical method and numerical simulation are conducted in the penetration process of piles under the load of both self-weight and hammer weight.An approach is proposed to determine self-penetration depth of the steel-pipe-pile.Geometric nonlinearity and pile-soil interaction are also considered to analyze the stability of the pile with modified Riks method.