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随着软土地区高层建筑及大跨桥梁等的承载力要求的提高,深长大直径扩底灌注桩因其单桩承载力高、经济效益好等优点得到较广泛的应用。但基于中短桩理论的计算标准与实测得到的深长大直径扩底桩的结果有较大差别,因而需根据现场试验结果分析软土中深长大直径扩底桩的承载性状和荷载传递机理。基于现场静载荷试验及桩身应力测试结果分析了深长大直径扩底桩的荷载传递机理和承载性状。研究表明,深厚软土地区深长大直径扩底灌注桩的侧阻先于端阻发挥,同时其荷载传递不同于等直径的灌注桩,深长大直径扩底灌注桩在荷载水平较高时会产生桩侧摩阻力软化;扩底桩的桩端扩大部分对承载能力影响较大,不仅影响到桩端阻力的发挥,还影响到桩侧阻力的发挥,深长大直径扩底灌注桩在低水平荷载作用下表现为摩擦桩性状,在高水平荷载作用下表现为端承摩擦桩性状。
With the improvement of the bearing capacity requirements of high-rise buildings and long-span bridges in soft soil areas, the deep and large-diameter expanded bottom grouting piles are widely used because of their advantages such as high bearing capacity and good economic benefits. However, the calculation criteria based on medium-short piles theory are quite different from the measured results of deep and large-diameter expanded piles. Therefore, the bearing behavior and load transfer mechanism of deep and large-diameter expanded piles in soft soil should be analyzed according to the field test results. Based on the field static load test and pile stress test results, the load transfer mechanism and bearing behavior of deep and large diameter expanded peg were analyzed. The research shows that the lateral resistance of deep, large and large diameter expanded bored piles in deep soft soil area precedes the end resistance, and its load transfer is different from the bored piles of equal diameter. The deep and large expanded bored piles will occur when the load level is higher The pile side frictional resistance softens; the expanded part of the enlarged bottom pile has a great influence on the bearing capacity, which not only affects the exertion of pile end resistance, but also affects the exertion of pile side resistance. The deep, large- Under the action of the performance of the friction pile, under the action of high horizontal load bearing pile performance.