大断面矩形过河顶管上浮风险分析及控制

Risk analysis and control of large-section rectangular river-crossing pipe jacking floating

复杂地质条件下,过河顶管施工常遇到上浮问题。从设计角度分析过河矩形顶管上浮风险,分析过河顶管施工中管片上浮的原因:顶管覆土、浮力、管片结构等因素,从增大覆土埋深、改良覆土性质、减小注浆压力、控制浆液浓度、提高顶管附加荷载5个方面进行抗浮风险控制,并提出考虑泥浆套压强、浓度因素的过河矩形顶管抗浮设计控制指标。根据龙岗路大断面过河矩形顶管工程设计经验得到:管线覆土增大3 m后,顶管上覆荷载提高40.5%,顶管自重及上覆荷载之和提高29.4%,浮力作用值提高21.9%;大断面过河矩形顶管覆土抗浮变形条件较难满足,顶管覆土抗浮变形在设计中需要慎重考虑。

Under complex geological conditions,floating Problems are often encountered during river crossing and pipe jacking construction.This paper analyzes the floating risk of rectangular pipe jacking from the perspective of design.Firstly,the reasons for the floating of segments in the construction of pipe jacking are discussed:the factors of soil covering,buoyancy and segment structure.The anti floating risk is controlled from five aspects:increasing the buried depth of soil covering,improving the properties of soil covering,reducing the grouting pressure,controlling the slurry concentration and increasing the additional load of pipe jacking,The anti floating design control index of rectangular pipe jacking crossing the river considering the factors of mud jacket pressure and concentration is put forward.According to the design experience of large section river crossing rectangular pipe jacking project in Longgang Road,it is obtained that:After the soil covering of the pipeline is increased by 3 m,the overlying load of the pipe jacking is increased by 40.5%,the sum of the pipe jacking self weight and overlying load is increased by 29.4%,and the buoyancy action value are increased by 21.9%;It is difficult to meet the anti floating deformation conditions of large cross-section rectangular pipe jacking,and the anti floating deformation of pipe jacking needs to be strictly considered in the design.