考虑开挖卸荷及变形耦合效应的被动桩分析方法  

Analytic method for passive piles considering excavation-induced unloading effects and deformation coupling effect

作　　者：郑俊杰[1] 章荣军[1] 潘玉涛[1] 崔岚[1] 

机构地区：[1]华中科技大学岩土与地下工程研究所,湖北武汉430074

出　　处：《岩土工程学报》2012年第4期606-614,共9页Chinese Journal of Geotechnical Engineering

基　　金：新世纪优秀人才支持计划资助项目(NCET-06-649)

摘　　要：基坑、隧道的开挖将不可避免地影响邻近受荷桩基的工作性能,如何合理评价开挖条件下邻近受荷桩基的附加响应至关重要。针对Winkler地基梁模型的不足,提出了一种改进的非线性两阶段分析方法,该法能够合理地考虑桩土作用的非线性特征、桩顶工作荷载对桩身附加轴力的影响及轴力产生的偏心弯矩对水平挠曲的影响等,并给出了该改进算法的增量法求解过程。同时将本文方法与已有研究成果进行了对比,验证了本文方法的合理性,并进一步探讨了桩顶工作荷载对竖向附加响应及轴向力对水平附加响应的影响规律。结果表明:桩顶工作荷载对竖向附加响应的影响是显著的;而轴向力对水平挠曲的影响程度则与自由场位移模式等相关,对于部分位移模式,影响也很显著。Excavation of foundation pits and tunnels will inevitably influence the working performance of adjacent loading piles, thus, it is important to accurately evaluate the additional pile responses due to soil excavation. In order to overcome the deficiency of the conventional Winkler＇s foundation beam model, a modified nonlinear two-stage analysis method is proposed. k can consider the nonlinear characteristics of pile-soil interaction, influence of pre-phase working load on the excavation-induced additional axial force as well as influence of axial force on the lateral deflection more factually. Combined with the incremental method, the solving process of nonlinear equations is then presented. Moreover, the calculated results are compared with those from other existing methods to verify the calculation accuracy of the proposed method, and a further study is made to investigate the influence laws of pre-phase working load on additional axial force and the axial force on lateral deflection. The results indicate that the influence of pre-phase working load on the vertical additional responses is significant; the influence degree of axial force on lateral responses is relevant to （but not limited to） the mode of free-field displacement, and under some situations, the influence of axial force on lateral responses is not negligible and the coupling effects should be rationally considered.

关 键 词：被动桩 开挖卸荷 变形耦合效应 自由场位移 非线性荷载传递法 增量法 

分 类 号：U452[建筑科学—桥梁与隧道工程]