At present,the research on anti-floating performance of pull-out resistant piles in tunnels mainly focuses on bear-ing 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 lat-eral 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 tun-nel and group piles are symmetrically distributed,and with the increase of pile number,the influence of group-pile effect increa-ses,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
Key words
pull-out resistant pile/group-pile effect/anti-floating design/indoor model test
维普
万方数据