敞口PHC短管桩在砂层地基中的应用研究  

Application of open PHC short pipe pile in sand foundation

作　　者：丁小伟 DING Xiao-wei(China Coal Xi’an Design Engineering Co.,Ltd.,Xi’an 710054,China)

机构地区：[1]中煤西安设计工程有限责任公司,陕西西安710054

出　　处：《煤炭工程》2022年第10期26-30,共5页Coal Engineering

摘　　要：结合具体工程,针对渭河二级阶地地表下20m左右的较厚密实砂层,利用桩端土塞效应对桩竖向抗压承载力的提高作用,选择锤击沉桩的敞口PHC短管桩地基增强方式,能够顺利沉桩并节省工期和工程造价。静载试验结果表明,在合理的沉桩条件下,随着桩顶荷载的增加,桩端挤入密实砂层约5.0~6.0d时,PHC400(AB)-95型敞口短管桩土塞效应较强,在砂层中的极限端阻力显著提高,提出PHC敞口管桩在以密实砂层为桩端持力层时,可考虑使用土塞效应作用下修正后的名义等效端阻力,修正系数为1.83~2.33。建筑物沉降观测结果与前期分析预测吻合。Combining with the analysis and comparison of foundation schemes for a 100 m commercial and residential building in the northern suburbs of Xi’an, in view of the relatively thick and dense sand layer about 20 m below the surface of the second terrace of the Weihe River, the open PHC short pipe pile foundation reinforcement method of hammer driven pile is selected by using the effect of soil plug at the pile end to improve the vertical compressive bearing capacity of the pile, which can successfully drive the pile and save the construction period and project cost. According to the comparative analysis of the static load test results, under the reasonable pile driving conditions, with the increase of pile top load, when the pile end is squeezed into the dense sand layer for about 5.0~6.0 d, the soil plug effect of PHC400(AB)-95 open short pipe pile is strong, and the ultimate end resistance in the sand layer is significantly increased. It is proposed that when PHC open pipe pile takes the dense sand layer as the pile end bearing layer, the modified nominal equivalent ultimate end resistance under the soil plug effect can be considered, and the correction coefficient is 1.8~2.3. The observation results of building settlement are consistent with the previous analysis and prediction, which provides a reference for the foundation design of similar sites.

关 键 词：敞口短管桩 土塞效应 静载试验 桩端阻力 工期和造价 

分 类 号：TU394[建筑科学—结构工程] TD984[矿业工程—选矿]