考虑水位变化影响的隧道抗拔群桩承载机理研究  

Study on bearing mechanism of pull-out resistant group piles in tunnels considering water level change

作　　者：曾俊雄 陆烨[2] ZENG Junxiong;LU Ye(China Railway Tunnel Group Co.,Ltd.,Foshan 528299,China;School of Mechanics and Engineering Science,Shanghai University,Shanghai 200444,China)

机构地区：[1]中铁隧道局集团建设有限公司,广东佛山528299 [2]上海大学力学与工程科学学院,上海200444

出　　处：《人民长江》2024年第12期186-194,共9页Yangtze River

基　　金：国家自然科学基金项目(52078286);浙江省交通运输厅科技计划项目(2021045)。

摘　　要：目前隧道抗拔桩抗浮的相关研究主要集中在单桩的承载机制上,但工程实践中隧道抗拔桩通常设计为群桩形式。依托浙江省衢州市荷一路过江通道工程,设计了考虑水位变化的隧道-群桩模型试验,同时结合数值模拟分析,对桩周土压力的变化规律、群桩承载机制及群桩效应展开研究。模型试验研究发现:桩体侧摩阻力的发挥从上而下是一个先增大到最大值而后减小的过程,达到极限状态时桩身侧摩阻力最大值是最小值的3倍以上;相比单桩,群桩之间土体由于受到挟持作用而未充分发挥桩体的极限承载力,三桩工况时的单桩平均极限承载力和群桩效应系数比双桩工况时分别减少7.23%和7.29%,说明随着桩数的增加桩体受到群桩效应的影响也在增大,每根桩的极限承载力发挥越发不充分。有限元模拟分析发现隧道及群桩结构中的应力呈对称分布,且随着桩数的增加,群桩效应影响增大,两侧边桩与隧道连接处的应力也增大。At present,the research on anti-floating performance of pull-out resistant piles in tunnels mainly focuses on bearing mechanism of single pile,however group piles are much more used in practical projects.In this paper,based on a project of river crossing at Heyi Road in Quzhou City,Zhejiang Province,we designed a model test of tunnel-group piles considering water level change,and at the same time,combined with the numerical simulation analysis,we studied the variation rule of soil pressure around the piles,the bearing mechanism of the group piles,and the group-piles effect.It is found that from top to bottom,the lateral friction resistance of the pile first raises to a peak then decreases,and the maximum lateral friction resistance is nearly three times of the minimum value in an ultimate state.Compared to a single pile,the ultimate bearing capacity of group piles don′t give full play due to the holding action on soil mass between piles.Especially the average ultimate bearing capacity of single pile and group-pile coefficient in the case of three piles are reduced by 7.23%and 7.29%,respectively compared with that in the case of two piles,indicating that with the increase of the number of piles,the pile body is more affected by the group-pile effect,and the ultimate bearing capacity of each pile is less played.The finite element simulation analysis shows that the stresses in the tunnel and group piles are symmetrically distributed,and with the increase of pile number,the influence of group-pile effect increases,and the stresses at the connection parts between the side piles and the tunnel on both sides also increase.

关 键 词：隧道 抗拔桩 群桩效应 抗浮设计 室内模型试验 

分 类 号：TU473.1[建筑科学—结构工程]