嵌岩扩底短桩抗拔承载性能现场试验研究及数值模拟

为研究嵌岩扩底短桩的抗拔承载性能,在现场完成了4根扩底短桩的抗拔静载试验,详细地分析了单桩Q-s曲线,并将现行规范计算的极限抗拔承载力与现场试验结果相比较。在通过PLAXIS 3D软件验证数值模拟结果与现场试验结果吻合的基础上,进一步深入探讨了水平荷载对扩底短桩抗拔承载特性的影响。结果表明:扩底短桩的Q-s曲线呈陡变型,极限状态桩顶上拔位移与桩径之比的平均值为1.94%;现行规范计算结果过于保守,公路规范相比其它规范计算结果与试验结果较为接近;当水平荷载与上拔荷载的比值η分别为10%,20%,30%时,极限抗拔承载力呈线性减小,相比η=0时分别减小8.3%,16.7%,25.0%。研究结果对优化桩基设计有重要的理论意义和工程应用价值。

Uplift Bearing Behavior of Rock-socketed Short Piles with EnlargedBottom: Field Test and Numerical Simulation

Static uplift tests were performed on four short piles with enlarged bottom to investigate the uplift bearing characteristics of rock-socketed short piles with enlarged bottom. The Q-s curves of single pile obtained from the tests were analyzed in detail, and the field test result was compared with the ultimate uplift bearing capacity calculated by current codes. The field test results were verified consistent with numerical results by PLAXIS 3D. On this basis, the influence of horizontal load on the uplift bearing capacity of short pile with enlarged bottom was examined. The Q-s curves of short piles with expanded-bottom are steep, and the average ratio of uplift displacement to pile diameter is 1.94% in limit state. The calculation results of present codes are too conservative. Comparing with other codes, the calculation results of highway codes are closer to the test results. When η, the ratio of horizontal load to uplift load was 10%, 20% and 30%, respectively, the ultimate uplift bearing capacity of the pile decreased linearly by 8.3%, 16.7% and 25.0% respectively compared to that when η=0.