Analysis and information construction of Pukou deep foundation pit of Nanjing Yangtze River tunnel   

Taking the deep excavation engineering at Pukou of Nanjing Yangtze River tunnel as an example,the measures for the safety monitoring and information construction of deep foundation pit are introduced.Different types of monitoring sections are designed based on different maintenance structures.The monitoring content includes settlement and displacement,bottom heave in foundation,ground water level,internal force of piles and slurry walls,support axial force,water pressure and earth pressure,etc.Based on construction conditions,the monitoring data of leading path segment,hiding building segment,shield originating working well and engineering circumference circumstance are analyzed.The analytical results show that the support system force is improved by lowering the ground water level outside the deep foundation pit,but the surrounding circumstance is greatly affected by large-scale lowering of ground water.The deformation and internal force of supporting structure are interrelated with the support setting and construction conditions.The monitoring feedback results duly guide the construction of deep excavation.The experience and conclusions can be the reference for the design,construction and researches of similar projects.