桩侧及桩端后注浆对超长桩承载力的影响

摘要

Taking a cross-sea bridge in Hainan Province as the engineering background, and with a method of the parallel contrast experiment, we apply static load tests to test the vertical compressive capacity of the three super-long bored piles, and record the friction of each part of the pile and pile tip resistance during the test.We also analyze the effects on the post-grouting on the piles capacity, the law of load transfer, and the characteristics of the resistance on the pile side and pile tip by comparing the test results. The results show that the post-grouting can improve the bearing capacity of the super-long bored piles and reduce the settlement.For the super-long bored piles, the effect of the pile-side grouting on the capacity is much greater than that of the pile tip grouting. After the grouting, the law of load transfer of the super-long pile is the same, the resistance of the upper side is activated before that of the lower side.The soil of the grouting section shows a cementing strength with the pile cement, while the shear strength is greater and the shear stress increases faster with the increase of the displacement.%以海南省某跨海大桥为工程背景,采用平行对比试验法,以桩侧桩端后注浆及施工桩长为变量,对3根超长灌注桩进行了竖向抗压静载试验,并对试验过程中试桩穿越各土层的分段侧摩阻力及桩端阻力进行测试.通过比对试验结果,分析桩侧桩端后注浆对超长灌注桩承载力性状、 荷载传递规律及桩侧、 桩端阻力发挥特性的影响.结果表明:进行桩侧、桩端后注浆能显著提高超长灌注桩的承载能力,减小桩基沉降;对于超长灌注桩,桩侧注浆对承载能力的增加效果远远大于桩端注浆;桩侧桩端注浆后,超长桩的荷载传递规律不变,依然是上部侧阻力先于下部侧阻力激发;桩侧注浆处土体表现出与桩体水泥胶结的性质,其抗剪强度较大且随位移增长而增加得更快.