海上试桩不同桩型承载力特性研究

Study on Characteristics of Bearing Capacities of Different Offshore Test Piles

天津南港某高桩码头拟建场地有深厚密实砂层,通过试桩测定设计桩型对砂层的穿透及贯入能力,研究不同基桩承载力特性。试验结果表明:混凝土预制桩及钢管桩均有较好的穿透及贯入能力;基桩轴向极限承载力高应变检测结果小于静载试验,误差均在5%以内;混凝土预制桩桩端承载力占总承载力不小于44.6%,钢管桩桩端承载力占总承载力不小于21.9%;相同荷载作用下,混凝土预制方桩静载与动载沉降量之比为1.40,钢管桩为0.90,两者差异明显;基桩承载力达到极值时桩侧摩阻力要明显大于规范极限侧摩阻力,规范取值偏保守。

The proposed site for a piled wharf in Tianjin South Port is covered with thick dense sand layer.Therefore,test piles can used to measure the penetration of the designed piles into the sand layer as well as the bearing capacities of different pile foundations.The test results show that either precast concrete pile or steel pipe pile has better penetration performance.The high strain detection for the axial ultimate bearing capacity of the foundation pile leads to a smaller result than that of the static load test,and the deviations are within the range of 5%.The bearing capacity of the precast concrete pile end shall not be less than 44.6%of the total bearing capacity,and the bearing capacity of the steel pipe pile end shall not be less than 21.9%of the total bearing capacity.The settlement ratio of the precast concrete square pile under same static and dynamic load is 1.40,and that of the steel pipe pile is only 0.90.After the extreme bearing capacity of the foundation pile is reached,its lateral friction shall be significantly greater than the extreme value specified in the code,namely,the latter one is conservative.