现浇混凝土大直径薄壁管桩桩内外侧壁摩阻力特征分析

ANALYSIS OF THE INNER AND OUTER LATERAL RESISTANCE CHARACTERISTICS OF THIN WALL PIPE PILE WITH CAST-IN-PLACE CONCRETE

现浇混凝土大直径薄壁管桩(PCC桩)的侧阻由外侧壁摩阻力和内侧壁摩阻力构成。采用模型试验和理论分析方法,研究了PCC桩的内、外壁侧摩阻力发挥机理和分布特征。结果表明:随荷载增加,外侧壁摩阻沿桩身分布先增后减,且其极值先于内侧摩阻力产生;加载初期,内侧壁阻力随外荷载加大但趋势并不明显,加载后期,内侧壁阻力出现显著增大且趋势明显。桩筒内土体因受内壁约束,芯筒内土在加载初期以竖向压缩变形为主,随外荷载增大桩筒内侧壁摩阻力持续增大,这是内侧摩阻不同于外壁侧阻的根本原因。

The lateral resistance of thin wall pipe pile by using cast-in-place concrete（ PCC Pile） consists of two parts： inner lateral resistance and outer lateral resistance. The model test and analytical solution were adopt to analyze the development mechanism and distribution characteristics of PCC pile. The results showed that outer lateral resistance of PCC pile increased firstly and then decreased,the ultimate outer lateral resistance existed prior to inside lateral resistance. Inner lateral resistance increased at the earlier stage of loading,and the increasing trend was not obvious. However,at the later stage of loading,the inner lateral resistance increased remarkably,and the increasing trend was obvious. Because the inner soil of the PCC pile was restricted by the inner wall,the soil mainly presented vertical compress deformation,and the inner lateral resistance increased continually with the increase of the load,which indicated the basic reasons for the differences between inner lateral resistance and outer lateral resistance.