通过对庆阳某超高层建筑6根钻孔灌注桩进行大吨位静载试验,对比分析6根长短灌注桩的承载力与沉降性能,结果表明设计混凝土灌注桩竖向抗压极限承载力不大于14 000 kN时,与短桩相比,长桩对提高承载力、减少沉降的效果不明显,从而体现了试桩的重要性;在预估桩身沉降计算中,存在一个引起桩端土体压缩的临界荷载,只有当加载大于临界荷载时才需考虑桩端土体的压缩;采用简化方法计算桩身压缩量反推出长桩和短桩的综合系数分别为0.48和0.46,故规范推荐的系数0.5偏大.%Through the large tonnage static load tests of the 6 bored piles of a super high-rise buildings in Qingyang area, comparing the results of the bearing capacity and settlement performance of the six long piles and short piles, the results shows that the effect is not obvious to improve the bearing capacity and reduce settlement through increasing the pile length, when the vertical compressive ultimate bearing capacity is less than 14 000 kN, so test pile is very important; In the process of calculating the settlement of pile body, the compression of pile endpoint soil should be considered only when the load is greater than the critical load; the composite coefficient of long pile and short pile were 0.48 and 0.46 by using simplified methods for calculating the pile body compression, so the standardized coefficient 0.5 is larger.
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