地铁隧道管片错台风险评估体系的研究和探讨

Research on Risk Assessment System of Segments Dislocation in Metro Tunnel

管片错台是盾构施工过程中的常见现象,会引发管片局部破损(开裂)、盾尾漏浆、隧道漏水等风险,而导致错台的主要因素有同步注浆控制、盾构姿态、总推力反力竖向分力、掘进速度、地层条件和拼装作业等。基于风险评估理论,笔者采用广义函数法建立地铁隧道的风险评估体系。利用G1法计算风险指标的权重;由风险指标与错台量的关系,将定性指标予以量化,同时,按照统一标准进行规范化,得到其价值标准;计算系统的总价值,将系统的安全等级划分为优、良、中、差4级。采用此评价体系对地铁隧道进行管片错台风险评估,得出量化的评估结果,进而为选取掘进参数和提出施工对策提供依据。

Lots of risks exist in segments dislocation,such as segments local cracks(or breakage),plasma leakage of shield tail or tunnel leaks and so on. Those are mainly caused by synchronized grouting control,shield attitude,vertical component force,tunneling speeds,ground conditions and segments assembling. With the help of risk assessment method and generalized function method,a risk assessment system of the segments dislocation in metro tunnel was established. Weight of each risk index was calculated by G1method; the value standards of each risk indexes were built,which was based on their influences on shield segments dislocation,as well as the various index must be normalized; at last,total value of the system was calculated and the security grade was put forward,including four grades: excellent,good,common,poor. As using the system to assess the segments dislocation of each metro tunnel,we can get the quantitative assessment results to provide basis for selecting tunneling parameters and putting forward construction countermeasures.