为探究既有区间在新建隧道盾构下穿过程中施工沉降控制方法与既有结构沉降变化之间的关系,依托深圳地铁10 号线岗厦北站—莲花村站区间(以下简称岗莲区间)左线隧道盾构下穿既有2 号线工程开展既有结构变形监测,结合现场监测数据,建立模拟隧道施工的计算模型,分析得到既有结构在下穿过程中变形与下穿施工控制方法间的关系。研究表明: 1)同步注浆等施工控制方式对既有结构初期变形影响较大,二次注浆对变形稳定时间及大小影响较大; 2)下穿过程需重视盾构土舱压力的维持,并采取保压措施,在较高水平上维持土舱压力,保持刀盘前方水土; 3)管片脱出盾尾后及时二次注浆,充分充填壁后空隙,在既有结构沉降较大时应及时二次注浆进行补救。

The settlement control of the existing tunnel under shield tunneling is a key and high-risk problem in metro constructions. In order to explore the relationship between the construction settlement control methods and the settlement variation of existing structure in the process of underneath-pass excavation, the deformation of the existing structure of Shenzhen Metro Line 2 induced by underneath crossing of left-line of Gangxiabei Station-Lianhuacun Station on Shenzhen Metro Line No. 10 is monitored. A finite element calculation model is established based on the site monitoring data, and the relationship between the deformation of existing structure during shield crossing and the underneath crossing construction control method is obtained. The analytical results show that: (1) The synchronous grouting has a great influence on the initial deformation of the existing structure, and the secondary grouting has a great influence on the deformation stability time and size. ( 2) During the underpass process, it is necessary to pay attention to the maintenance of shield soil chamber pressure to maintain the chamber pressure at a higher level, and further to keep water and soil ahead of shield cutterhead. (3) The secondary grouting should be carried out in time after the segment comes out of shield tail, the hollows behind segment should be fully filled, and the secondary grouting should be carried out in time