预应力管桩侧摩阻力影响因素的研究

RESEARCH ON INFLUENCE FACTORS OF SIDE SOIL RESISTANCE OF PHC PIPE PILE

桩侧摩阻力在各种情况的影响下变化较大,为能准确对其进行取值需对其影响因素进行研究。从侧摩阻力的机制分析推知,侧摩阻力的决定因素为桩土界面强度、土体的强度以及土体的应力状态。土体的应力状态是造成侧摩阻力变化的根本原因,它不仅会影响到桩土界面强度的取值,还会使土体在强度条件一定的情况下表现出不同的抗剪能力。介绍3根预应力管桩的内力测试成果,利用ADINA有限元软件对试验桩进行3个方面的分析:破坏可能发生位置、桩土界面参数的取值、桩侧土压力随土层深度及桩荷载的变化。通过分析发现,3根管桩的破坏均发生在界面处。对于淤泥土桩土界面力以黏着力为主;对砂质土或全风化岩桩土界面力以摩擦力为主,此时桩侧土压力的变化会对桩侧摩阻力极值有影响。

It is founded that the value of side soil resistance of pile will change distinctly in different situation,to determine it more accurately the influence factors of it need to be researched.Based on the mechanism analysis it can be concluded that the determinant influence factors of side soil resistance of pile are the strength of pile-soil interface,the strength of soil and the stress condition of soil.The stress condition of soil is the main reason which causes the variety of side soil resistance of pile,because it will change in different situations,influence the value of pile-soil interface strength,and make soil have different shearing-resistant abilities under a certain strength condition.An internal force test of three PHC pipe piles and its results are introduced.ADINA software is used to analyze the testing piles.The analysis includes possible destroy positions,pile-soil interface parameters and the changes of side soil pressure of pile in different depths of soil and under different loads.It is founded that damages all occur in the pile-soil interface of three testing piles,so the pile-soil interface parameters can be worked out using the testing value of side soil resistance.It is found that for silt soil adhesive force is the main interface force,but for sandy soil or residual soil,the friction is the main interface force.When friction is the main interface force,the change of side soil pressure of pile can cause the variation of side soil resistance of pile.