角桩缺损情况下群桩基础承载特性分析  

Analysis on bearing characteristics of pile group foundation with a defective corner pile

作　　者：马缤辉[1,2] 郭佳乐 曾星 胡志勇 沈明燕 Ma Binhui;Guo Jiale;Zeng xing;Hu Zhiyong;Shen Mingyan(School of Civil Engineering,Hunan University of Science and Technology,Xiangtan 411201,China;Hunan Provincial Key Laboratory of Geotechnical Engineering for Stability Control and Health Monitoring,Xiangtan,411201,China)

机构地区：[1]湖南科技大学土木工程学院,湖南湘潭411201 [2]岩土工程稳定控制与健康监测湖南省重点实验室,湖南湘潭411201

出　　处：《工程勘察》2019年第12期17-23,共7页Geotechnical Investigation & Surveying

基　　金：国家自然科学基金(51778227、51308208);湖南省科技创新平台与人才计划项目(2016RS3032);湖南省自然科学基金(2015JJ3069)

摘　　要：某连续刚构桥1号墩采用3×3的群桩基础,桩基超声检测发现承台下角区一根角桩桩身完整性不良,经钻孔验证其桩身存在缺损。为保证安全,分别按照缺损角桩为摩擦桩和缺损角桩缺失两种工况进行了桩基承载力验算,并进一步采用数值模拟方法,分析缺损角桩对群桩基础承载特性及承台受力变形的影响。结果表明,承台最大主拉应力、最大主压应力作用区域随角桩缺失区域移动;考虑最不利情形,角桩缺损时承台的应力和变形变化不大;角桩缺损对承台以及上部结构承载能力及正常使用性能的影响较小。同时考虑桥梁长期服役性能,建议对缺损角桩进行桩端后压浆处理,以防止缺损角桩桩端沉降过大导致群桩承载力下降而危害桥梁结构安全。Group pile foundation with 3×3 is adopted in a continuous rigid frame bridge.Through ultrasonic test on the piles,it is found that the integrity of one corner pile in the lower corner of the cap is poor,and the pile shaft is confirmed defective by coring.In order to ensure the safety,the bearing capacity test of the pile foundation is analyzed in two situations including considering the defect pile as friction piles and without considering the piles.The bearing characteristics of the pile group and the deformation of the pile cap are simulated by numerical method.The results show that the maximum main tension and compressive stress area of the cap shifts with the location of the missing corner pile;considering the most unfavorable situation,the stress and deformation of the pile cap will not change much when the corner pile is damaged;the bearing capacity of the pile group and the normal service performance of upper structure will not be affected obviously by the corner pile defect.Considering the long term service performance of the bridge,it is recommended to carry out post-grouting into the bottom of the defect corner piles to prevent excessive settlement to endanger the bridge structure safety.

关 键 词：群桩基础 角桩缺损 桩基承台 数值模拟 承载特性 

分 类 号：TU473.1[建筑科学—结构工程] U445.7[建筑科学—土工工程]