后注浆抗拔桩在复杂地层下的试验及模拟研究

Study on experiment and simulation of post-grouting uplift piles in complex strata

以郑州某工程抗拔试桩单桩抗拔承载力试验结果为基础,针对抗拔桩抗拔承载力不足的情况,采用桩端桩侧复式后注浆工艺来减小泥皮和沉渣对桩侧摩阻力和端阻力的影响,从而提高桩抗拔承载力。对注浆结果进行分析并用经验公式计算。结果表明通过试验验证,由《建筑桩基技术规范》(JGJ 94—2008)公式计算的注浆量可适当减小。分析了有泥皮存在的情况下桩侧摩阻力的减小以及注浆后桩侧摩阻力的增强。最后对后注浆桩进行数值模拟,证明了后注浆尤其是加强桩端后注浆能明显提高抗拔桩承载力。

Based on test results of uplift bearing capacity of single uplift pile of a project in Zhengzhou, in view of the insufficient uplift bearing capacity of the uplift pile, the double-post grouting process of the pile end and pile side was adopted to reduce the influence of the mud and sediment on side friction resistance and end resistance of the pile, thereby improving uplift bearing capacity of the pile. The grouting results were analyzed and calculated by empirical formulas. The results show that normal grouting amount calculated by the formula of Technical specification for building pile foundations(JGJ 94—2008) can be appropriately reduced by experimental verification. The formula was used to analyze the reduction of pile side friction resistance and the enhancement of pile side friction resistance after grouting in the presence of mud. Finally, a numerical simulation of post-grouting piles was carried out, which proves that post-grouting, especially post-grouting to strengthen the pile end, can significantly improve the uplift bearing capacity of the uplift pile.