大直径桩沉降敏感性的数值分析  

Numerical Analysis of Settlement Sensitivity for Large Diameter Piles

作　　者：范臻辉[1] 王永和[1] 肖宏彬[2] 

机构地区：[1]中南大学土木建筑学院,湖南长沙410075 [2]湖南工业大学岩土工程研究所,湖南株洲412008

出　　处：《湖南工业大学学报》2008年第3期12-16,共5页Journal of Hunan University of Technology

基　　金：国家自然科学基金资助项目(50678177);湖南省自然科学基金资助项目(01JJY3043)

摘　　要：以某桥梁大直径桩为例,采用弹塑性有限元法分析了桩周土、桩端土以及桩土界面特性等因素对大直径桩沉降的影响。土体本构关系采用Drucker-Prager弹塑性模型,桩身混凝土采用线弹性模型,而桩土界面采用接触面单元进行模拟。结果表明:该桩的荷载-沉降曲线为缓变形,无陡降段,其极限承载力应以桩顶沉降来控制,在10.2 MN的设计荷载作用下,桩顶沉降仅为14.94 mm,具有较大的安全储备;在各影响因素中,桩周土对该桩沉降的影响最敏感,其次为桩端土;在工程实践中,提高桩周土强度、合理选择持力层以及避免破坏桩土界面强度是减少桩基沉降、保证上部结构安全性的有效手段。The settlement of pile foundation of a bridge can affect the safety of the bridge itself and the vehicles on the bridge. However, the complexity and variability of pile foundation as well as the randomness in construction make it uncertain to identify the settlement of pile foundation. Based on large diameter pile foundation of a bridge, it utilizes the elastic-plastic FEM to analyze the factors that affect the pile settlement, such as the pile-side soils, pile-end soils and the characteristics of the pile-soil interface. The soil constitute is assumed to be Drucker-Prager elastic-plastic model, the concreted pile shaft is considered as the linear elastic model and the soil-pile interface is monitored by contact elements. The results show that the pile foundation design for this bridge is reasonable with enough safety potential. Moreover, pile-side soil is the most sensitive factor to affect pile foundation settlements, and then is the pile-end soil. In engineering practice, improving the strength of pile-side soil, properly selecting support layer and avoiding destroying the strength at the pile-soil interface are the effective measurements to decrease the pile foundation settlements, ensuring the superstructure＇s safety.

关 键 词：大直径桩 沉降 敏感性 有限元法 

分 类 号：TU473.1[建筑科学—结构工程]