现浇X形桩复合地基桩侧摩阻力分布特性

Behavior of Side Friction of X-section Cast-in-place Concrete Pile Composite Foundation

依托南京市桥北污水处理厂现场静载荷试验,应用ABAQUS软件分别建立了现浇X形单桩复合地基、群桩(梅花形布置和正方形布置)复合地基桩侧摩阻力的模型。结果表明:现浇X形桩中性点出现在桩长1/4～1/3深度处,负摩阻区明显存在但小于正摩阻区,是典型的摩擦型桩;侧摩阻力随桩体模量、土体参数和一定范围内桩长的增大而增大,随褥垫层厚度的增大而减小;布桩间距影响侧摩阻力的发挥,在允许的承载范围内,应尽量增大布桩间距,优化侧摩阻力的分布。

Based on static load tests in Qiaobei sewage treatment plant in Nanjing,finite element models were established by ABAQUS for single pile and pile group with the configurations of equilateral triangle and square to simulate the distribution of side friction.The results show that the neutral points emerge at the 1/4 to 1/3 of pile depth.The area of negative friction is smaller than that of positive friction,in other words,X-section cast-in-place concrete pile（XCC pile） is a typical friction pile.The side friction increases with the increasing of pile modulus,surrounding soil modulus and pile length,and decreases with the increasing of cushion thickness.The capacity of side friction is affected by pile configurations.In order to improve the side friction,the pile spacing should be large enough within bearing capacity.