大直径双模盾构浅覆土无障碍始发变形控制研究  

Study on the Deformation Control of Non-barrier Launching of Large Diameter Double-mode Shields at Shallow Depth

作　　者：魏力峰 田扬 朱牧原 邹坤秘 方勇[1] WEI Lifeng;TIAN Yang;ZHU Muyuan;ZOU Kunmi;FANG Yong(Key Laboratory of Transportation Tunnel Engineering,Ministry of Education,Southwest Jiaotong University,Chengdu 610031;China Railway No.2 Engineering Group Co.,Ltd.,Chengdu 610015)

机构地区：[1]西南交通大学交通隧道工程教育部重点实验室,成都610031 [2]中铁二局集团有限公司,成都610015

出　　处：《现代隧道技术》2023年第2期149-158,共10页Modern Tunnelling Technology

基　　金：国家自然科学基金(52078428);四川省杰出青年基金项目(2020JDJQ0032)。

摘　　要：为探究浅埋环境下大直径双模盾构无障碍始发过程中的变形控制策略,依托新建成蒲铁路紫瑞隧道盾构掘进区间工程,利用FLAC 3D软件建立可视化数值模型,并结合现场监测数据和施工参数,对双模盾构无障碍始发全过程进行模拟,研究刀盘切削洞门围护桩时所施加刀盘推力的数值特征对于桩后土体位移的影响;通过对比不同加固范围的位移控制效果,验证传统加固理论及其改进方法在无障碍始发下的应用可行性。结果表明:(1)刀盘推力的数值特征对于桩后土体位移的影响存在地层差异性,黏性地层下的影响效果要显著于圆砾、砂卵石这类非黏性地层;(2)不论何种地层,刀盘推力梯度对于桩后土体位移的影响效果均要显著于推力数值大小;(3)传统加固理论及其改进方法在无障碍始发下仍可应用,其中横向加固宽度的理论计算值偏于保守,纵向加固长度则基本满足土体稳定性要求;(4)始发段盾构模式转换位置的选择对于后续施工引起的地表竖向位移有着显著影响,建议选在加固区域内或靠近加固区边界处。To investigate the deformation control strategy during the non-barrier launching of large-diameter dou⁃ble-mode shields at the shallow depth conditions,a study is conducted based on the shield-driven running tunnel section of the Zirui Tunnel on the new Chengdu-Pujiang Railway.A visual numerical model is established by using the FLAC3D software and taking into account field monitoring data and construction parameters to simulate the whole process of the non-barrier launching of a double-mode shield,and to study how the numerical characteristics of the cutterhead thrust applied when the cutterhead is cutting the retaining piles at the tunnel portal will affect the soil displacement behind the piles.The application feasibility of the traditional reinforcement theory and its im⁃proved methods under non-barrier launching are verified by comparing the displacement control effects at different reinforcement ranges.The results show that:(1)There is a stratigraphic variability in the influence of the numerical characteristics of the cutterhead thrust on the soil displacement behind the piles.Specifically,the effect in cohesive strata is significantly greater than that of non-cohesive strata such as gravel and sandy pebble strata;(2)The effect of the cutterhead thrust gradient on the soil displacement behind the piles is significantly greater than the numerical value of the thrust,regardless of the stratum types;(3)The traditional reinforcement theory and its improved meth⁃ods are still applicable under the non-barrier launching,where the theoretical calculation value of the transverse re⁃inforcement width is relatively conservative,and the length of the longitudinal reinforcement can basically meet the requirements for soil stability;(4)The choice of the location for the shift of the shield mode at the launching section has a significant impact on the surface vertical displacement caused by the subsequent construction,and the study suggests that this location shall be chosen within or near the boundary of the rei

关 键 词：双模盾构 浅覆土 无障碍始发 端头加固 模式转换 变形控制 

分 类 号：U455.31[建筑科学—桥梁与隧道工程]