青岛地铁某盾构掘进中地面塌陷事故分析

ANALYSIS OF GROUND COLLAPSE ACCIDENT IN SHIELD TUNNELING OF QINGDAO METRO

目前土压平衡盾构因其安全性高、施工速度快等特点已被广泛的应用在城市地铁隧道中,施工中经常发生进土量与出土量不平衡导致地表沉降超标甚至塌陷的问题。文中通过研究螺旋机转速和推进速度的匹配关系,来达到控制出土量的目的,首先总结了进土量和出土量的计算公式;然后利用渣土的切线变形模量概念,研究了土仓压力增量与盾构推进速度和螺旋输送机转速的关系模型,最后利用该模型及青岛地铁盾构施工监测平台分析了青岛地铁某盾构区间掘进过程中发生的塌陷事故,研究发现计算的超出土方量与塌坑的体积基本相符,后续盾构稳定掘进时,推进速度应控制在34~55mm/min之间,为同类型盾构施工提供了一定的理论指导。

At present, earth pressure balance shield has been widely used in urban metro tunnels because of its high safety,fast construction speed and other characteristics. In shield tunneling construction, the unbalanced amount of soil input and excavation often causes the problem that excessive ground settlement or even collapse. In this paper, the matching relationship between screw speed and propelling speed is studied to control the quantity of excavation. Firstly, we summarizes the formulas for calculating the amount of input and output of soil,then the concept of tangent modulus of deformation of dregs is used. The relational model between pressure increment of earth silo and shield driving speed and screw conveyor speed is studied. Finally, the collapse accident occurred in a shield tunneling section of Qingdao Metro is analyzed by using the model and the shield construction monitoring platform of Qingdao Metro. It is found that the calculated excess earthwork is basically consistent with the volume of the collapsed pit. When the shield tunneling is stable, the driving speed should be controlled between 34-55 mm/min, which provides a theoretical guidance for the construction of similar shield tunnels.