基于美国标准的桩基竖向承载力计算分析

Analysis of Vertical Bearing Capacity of Pile Foundation Based on American Standard

为了进一步提高中国海外项目质量,阐述了美国国家公路与运输协会桥梁设计规范AASHTO LRFD方法和基于静力触探试验的LCPC桩基础承载力计算方法,对比分析了中国标准与美国标准桩基承载力设计方法的异同。根据海外某工程的计算示例和对比分析,得到了不同桩基竖向承载力计算方法的结果及其规律。结果表明:AASHTO LRFD法和基于静力触探试验的LCPC法计算的桩基承载力较为接近;《公路桥涵地基与基础设计规范》由于其桩摩阻力标准值较小,桩端在砂性土中承载力容许值存在限制等因素的影响,其计算得出的桩侧摩阻力和桩端阻力均较小;采用AASHTO LRFD方法时,地下水位埋深和标准贯入试验等原位测试结果对计算结果影响较大;基于美国标准的海外项目勘察侧重原位测试结果,在勘察外业工作中应重视其操作的标准性。

In order to further improve the quality of China’s overseas projects,the bearing capacity calculation methods of AASHTO LRFD method and LCPC method based on static cone penetration test were expounded.The similarities and differences of pile foundation bearing capacity design methods between Chinese standards and American standards were compared and analyzed.According to the calculation example and comparative analysis of an overseas project,the results of different pile foundation vertical bearing capacity calculation methods were obtained.The results show that the pile foundation bearing capacity calculated by AASHTO LRFD method and LCPC method based on static cone penetration test are close.Due to the small standard value of pile friction and the limitation of allowable value of pile end bearing capacity in sandy soil,the calculated pile side friction and end resistance are small based on Specifications for Design of Foundation of Highway Bridges and Culverts.Through the analysis,it is also obtained that the in-situ test results such as groundwater buried depth and standard penetration test have great influences on the calculation results by using AASHTO LRFD method.The overseas project geotechnical investigation based on American standard focuses on the in-situ test results,and attention should be paid to the standardization of its operation in the field work.