基于静动法的大直径超长桩承载力实测分析

Actual Analysis of Bearing Capacity of Piles with Super large Diameter and Deep Penetration Based on Statnamic Method

摘要:

大直径超长桩在海洋工程和桥梁工程中应用广泛，但目前常用的测试方法均有各自的局限性。针对普通静载费时费力，自平衡测试方法研究不够完善等不足，基于马来西亚槟城二桥工程，采用现场实测方法对砂土地层中大直径超长嵌岩桩的静动法测试进行研究。通过对同一根桩上的自平衡法测试结果进行对比，分析静动法测试大直径超长桩承载力的适用性。通过对比发现，静动法测试结果用传统卸荷点法和分段卸荷点法处理得到的等效静承载力比自平衡法大30%左右；且由于土动摩阻和孔隙水压力影响，静动法测得的桩身摩阻力也大于自平衡测试结果，需要进行修正。

Abstract:

Piles with super-large diameters and deep penetration are widely used in ocean and bridge engineering；however，traditional capacity test methods used for such piles have limitations.Focusing on the imperfections of normal static load and Osterberg cell （O-cell） methods，the statnamic testing method is investigated on the basis of the Second Penang Bridge project in Malaysia.The capacities of piles with super-large diameters and deep penetration in sandy strata are studied.Compared with the results of the O-cell method used on the same pile，the applicability of statnamic testing for super-large diameter，deep penetration piles is analyzed.Results indicate that the equivalent static capacities resulting from the Unloading Point Method （UPM） and the Segmental Unloading Point Method （SUPM） are 30% larger than the results when using the O-cell method.Because of the influences of dynamic soil resistance and pore pressure，the side friction of statnamic testing is also larger than that when using the O-cell method.Therefore，the statnamic method still requires modification.