盾构穿越河流段施工过程中发现,管片在脱出盾尾3～4环出现上浮.主要从管片受力、承压水、建筑空隙及同步注浆等方面进行研究并制定相关控制技术措施.经过分析,盾构在刚进入河流下坡段的理论建筑空隙为管片上浮提供了自由空间;盾构在下穿河流的过程中覆土的突然减小、受到向上的合力、为管片上浮提供了动力;同步浆液及注浆的形式造成管片的不稳定性.通过理论结合实际对管片上浮进行控制,保证了后续顺利施工.%During the construction process of shield tunneling through river section,it is found that the segments rise up and fall in the 3～4 ring of the shield tail.This paper mainly studies from the segment pressure,pressure water,construction gaps and synchronous grouting and other aspects and makes relevant control measures.After analysis,it is found that the theoretical building space where the shield just enters the downhill section provides a free space for the segment to float up;the sudden reduce of casing and the upward force provide power for the segment to float up during the shield down passing through the river;synchronous slurry and the form of grouting caused the instability of the segment.Measures are taken to control the segment floating up combining theory with practice,which ensures smooth follow-up construction.
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