Construction of a large-section long pedestrian underpass using pipe jacking in water-filled clay

Abstract This paper presents a design and construction schemes of a pipe jacking project in Kunming, China in detail. The underpass, having a width of 6.9 m and a height of 4.9 m, was jacked 46m in water-filled clay under a busy viaduct with 4.5 m overburden soil., Some adjustments have been made to the construction process due to the characteristics of the soil layer, the surrounding environment and the existing pipeline. During the whole construction process: the pipe jacking passes through the shallow confined aquifer with high water content and high void ratio, it is easy to produce rheology. In addition, the attitude control of whole tube is also a difficulty, and some adjustments have been made to this problem; the monitoring scheme has also been adjusted accordingly. In general, this project is completed successfully and the traffic on ground and viaduct runs well during the whole construction process.