基于土体损失模型软弱地层超大直径钢顶管施工土体变形分析

Soil deformation based on soil loss model in soft ground with super-large diameter steel pipe jacking

针对顶管施工引起的土体变形问题,结合深圳市超大直径钢顶管施工项目,基于非等量径向土体损失模型,对Peck公式进行修正,计算得到该地区土体损失率为1.34%,并依托工程实例分析了软弱地层钢顶管施工土体变形规律。分析结果表明:土体损失是引起土体变形的主要因素,顶管顶推力次之,摩阻力对土体变形不敏感;从纵向分析,土体变形具有衰减性,受扰动区域在掌子面前方5 m范围内;从横向分析,土体变形具有扩散性,受扰动区域主要集中在顶管左右两侧6 m及软弱地层内;数值模拟结果与修正Peck曲线、现场实测拟合曲线吻合性良好。通过以上分析认为对软弱地层超大直径钢顶管施工土体易产生变形的区域,应采取一定措施减少其扰动程度。

Aiming at the problem of soil deformation caused by pipe jacking construction,this paper combines the construction project of super-large diameter steel pipe jacking in Shenzhen.Based on the non-equivalent radial formation loss model,the Peck settlement tank formula was revised,and the soil loss rate was obtained 1.34%.Combined with engineering examples,the law of ground deformation was analyzed during steel pipe jacking construction in soft ground.The analysis results show that soil loss is the main factor causing soil deformation,followed by pipe jacking force,and frictional resistance is not sensitive to soil deformation.From the longitudinal analysis,the soil deformation is attenuated,and the disturbed area is within 5 m in front of the excavation.From the horizontal analysis,the soil deformation is diffusible,and the disturbed area is mainly concentrated in the 6 m nearby the pipe jacking and the weak formation.The numerical simulation results are coincidence with the modified Peck curve and fitting curve on site.Through the above analysis,it is believed that certain measures should be taken to reduce the degree of disturbance in the areas,where the soil is prone to deformation during the construction of super-large diameter steel pipe jacking in soft formations.