南京纬三路过江通道超大直径泥水盾构始发关键技术研究

Research on Key Technologies for Launching of Super-large Slurry Shield:Case Study on Weisanlu River-crossing Tunnel

南京纬三路过江通道工程始发段具有覆盖土层薄、左右线间距小、始发进洞坡度大、曲线始发、始发井空间小等特点。通过相关工程经验比选,采用水泥搅拌桩加固和冻结加固,由于始发段不能在始发架上转弯,因而采用割线始发技术;始发进洞时,洞门密封钢环的密封方式与安装精度决定了始发阶段的密封效果,本文介绍了一种新型的洞门密封方式;由于始发井设计长度方向空间不够,将钢负环设计为常规管片的分块方式,采用管片拼装机进行拼装;针对南京纬三路工程地质情况,系统地介绍了始发泥水建压技术。采用以上关键技术,纬三路过江通道工程始发阶段盾构实际掘进姿态与设计姿态保持在规范允许范围内,始发架牢固可靠,钢负环拼装定位精确,密封钢环密封效果良好。

The shield launching section of Nanjing Weisanlu river-crossing tunnel has such features as shallow overburden, small spacing between the left tunnel tube and the right tunnel tube,large gradient,curved launching and small launching shaft.Cement mixing piles and freezing are adopted to reinforce the shield launching section.Because the shield cannot make a turn during launching,secant launching technology is adopted.Proper selection of launching soft eye seal structure and high seal structure installation accuracy provide excellent sealing for the shield launching.A new launching soft eye seal structure is introduced in this paper.The negative steel ring is designed in the form of normal segments and is assembled by the erector,because the longitudinal space of the launching shaft is not big enough to lift the negative ring. Besides,techniques for slurry pressure establishment,which are determined on basis of full consideration of the geology conditions,are systematically presented.By adopting the key technologies presented above,the slurry shield for Weisanlu river-crossing tunnel in Nanjing has bored through the launching section successfully,with the tunneling position of the slurry shield matching well with the design position,the reaction frame being solid and reliable,the steel negative rings having been positioned precisely and the sealing of the launching soft eye being in good condition.