劲扩复合桩竖向抗压承载特性对比试验

Comparative Experiment on the Vertical Compressive Bearing Characteristics of the Expanded Stiffened Deep-cement-mixing Pile

劲扩复合桩是在水泥土搅拌桩同心沉入刚性桩,通过水泥土或芯桩实现扩体,进而组合形成具有扩体形态和力学特性的一种新型复合桩型。针对劲扩复合桩,通过同直径多桩型进行现场单桩载荷试验对比,研究多种桩型载荷-沉降(Q-S)曲线、桩身轴力分布以及桩身侧阻力特点,进而分析劲扩复合桩竖向承载能力和桩身侧阻力发挥特性。研究结果表明:劲扩复合桩的极限承载力是同直径钻孔灌注桩的1.39~1.69倍;劲扩复合桩Q-S曲线呈“缓降”型,表现出大直径桩的承载特性;劲扩复合桩侧阻力计算值与预制桩及灌注桩桩侧阻力经验值的比值平均值为1.54~2.50。

The expanded stiffened deep-cement-mixing pile(ESDP)is a new type of composite pile with expanding shape and mechanical characteristics,which is formed by concentric sinking rigid pile into cement mixing pile and expanding body through cement mixing pile or core pile.The filed loading test of multi pile types with the same diameter was carried out.Q-S curves,distribution of shaft axial force and characteristics of pile shaft friction were studied.Vertical bearing capacity and action of skin friction of the composite pile were analyzed.Experimental results show that the ratio of the vertical ultimate bearing capacity between composite pile and traditional bored pile is 1.39~1.69.The Q-S curve of the composite pile is of“slow down”type,which shows the bearing characteristics of large diameter pile.The average value of the ratio of the measured value of the skin friction of the ESDP with the empirical value of the skin friction of the precast pile and the cast-in-place pile is 1.54~2.50.