盾构隧道穿越水底浅覆土施工技术对策

从盾构开挖面平衡状态及隧道水底抗浮平衡条件着手，推导了土压平衡盾构开挖工作面水土压力与密封舱内压力动态平衡公式，得到了盾构穿越水底浅覆土保持土体及隧道稳定所需的最小覆土厚度。结合南京地铁南北线一期工程，提出超浅覆土情况下水底隧道盾构施工应采取的工程对策。并介绍了南京地铁试验段工程采取的措施及取得的效果。相关结论可供水底隧道、地铁区间隧道浅覆土进出洞盾构施工参考。

TUNNELING METHODS THROUGH RIVER(LAKE,SEA) BED UNDER SHALLOW COVERING BY SHIELD

By analyzing the equilibrium states of the tunneling face and the tunnel under water,the formulas about the balance between the water and soil pressure in front of working face and the pressure in the cabin given by shield is obtained. The smallest covering depth required by the safety of tunneling face and tunnel is given. Then,based on the Phrase One Project of Nanjing Metro North-South Line,some main methods dealing with the shallow underwater ground are provided. The effect of the presented methods is introduced. The obtained conclusion in this paper can be used to the tunnels through river bed and those under shallow covering by shield.