考虑泥皮效应的大直径超长桩离心模型试验研究

Centrifuge model tests on super-long piles with large diameters considering mudcake effect

摘要: 应用离心模型试验研究了深厚软土地基中考虑泥皮效应的大直径超长单桩的承载变形特性。试验结果表明,考虑泥皮效应后,桩侧极限摩阻力约为不考虑泥皮的65%～85%,单桩极限承载力下降约20%。同时研究了桩径、桩长、持力层性质对单桩极限承载力和桩侧摩阻力的影响。结果表明,高荷载水平作用下,大直径超长桩的桩侧土层摩阻力易发生软化,导致桩产生渐进破坏;淤泥质粘土中,桩侧摩阻力随桩径增加而降低,但降低幅度较小;桩侧摩阻力具有深度效应,对某一特定深度土层,随着桩进入土层深度的增加,桩侧摩阻力下降,可表示为(h/R)的函数。

Abstract: Based on the centrifuge model tests,the bearing and deformation characteristics of super-long piles with large diameters considering mudcake effect were studied.It was shown that the ultimate shaft resistance of piles considering mudcake was about 65%～85% of that without mudcake and the ultimate bearing capacity decreased about 20%.The effect of pile diameters,pile lengths and bearing stratum on ultimate bearing capacity and shaft resistance was studied.The shaft resistance degraded under heavy load.The shaft resistance of super-long piles degraded little with the increasing diameters in mucky clay.The shaft resistance decreased with the increasing embedded depth in a soil layer at a given depth and could be expressed as the function of h/R.