As an effective method to control the deformation of surrounding rock caused by urban tunnel excavation,the effect of isolation pile in"upper soft and lower hard"composite stratum is rarely studied.Based on the Longquan tunnel project of water diversion in central Yunnan Province,FLAC3D software was used to analyze the influence of parameters such as isolation pile posi-tion,pile diameter,pile length and pile top buried depth on the deformation control effect of tunnel lining and surface buildings in"upper soft and lower hard"composite stratum.The results show that the isolation pile can block the transmission of formation stress,and reasonable design parameters are the key to give full play to the barrier effect of the isolation pile.Under the same con-ditions,the limiting effect of the isolation pile on the ground displacement is better in the horizontal direction than that in the verti-cal direction.The closer the isolation pile is to the tunnel and the larger the pile diameter is,the better the deformation control effect is.The displacement of tunnel lining and surface buildings caused by tunnel excavation can be well controlled only when the isolation pile penetrates through the slip surface of the stratum and is embedded into the lower layer.It is suggested that the depth of embedding lower soil is 1/4 of the pile length.Properly setting the buried depth of the isolation pile top can reduce the traction effect of the isolation pile on the soil.It is suggested that the buried depth of the pile top is 1/5 of the pile length.The research re-sults supplement the effect of isolation piles in composite stratum,which can provide reference for the application of isolation piles in shallow buried composite stratum in cities.
关键词
隔离桩/复合地层/浅埋隧洞/围岩变形/控制效果/龙泉隧洞/滇中引水工程
Key words
isolation pile/composite stratum/shallow buried tunnel/surrounding rock deformation/control effect/Longquan tun-nel/water diversion in central Yunnan Province
维普
万方数据