No abstract

No abstract

No abstract

Pipe roof method is an effective way for urban underpassing scheme. Due to the successive jacking of multiple pipes, the characteristics of ground response are distinctly different from single pipe or twin pipes. In this paper, the gradual ground loss by successive pipe-jacking and the causes of settlement are analyzed. The conclusions drawn from this paper show that: (1) The maximum incremental was right above the pipe axis which could be controlled within 1mm. (2) The shield effect of the former pipe on the latter one resulted in a 50% reduction of maximum incremental settlement. (3) The distribution of cumulative settlement curve was reflected by superimposed effect of staged ground settlements. (4) The results of settlement monitoring illustrated that the field measured settlements were basically tally with those of the simulated values, the goodness of fit was more than 85%.

Due to the compact space and high utilization demands, the construction of large underground subway transfer station in urban area, like Pengcheng Square station in Xuzhou, China, was confronted with various obstacles, such as nearby surface and subsurface structures, heavy road traffic, and clay-rock mixed ground conditions. Based on careful investigations to all surrounding limitations, an innovative composite station form and its corresponding construction method, open cutting with underground excavation (OCUE) method, were introduced. The construction performance of this method has been confirmed by field monitoring. The main findings from the research include: (1) Sophisticated design and construction is essential for satisfying the expected functions of the station, minimizing the influence on the heavy traffic and sensitive structures in adjacent, as well as tackling the adversities of the clay-rock mixed strata; (2) Supported by the OCUE method, composite form of subway station was delicately designed to maximize the utilization of limited space, it comprised of open cutting part, underground excavation part and half-covered excavation part; (3) The implementation of OCUE method was successful with little influence on the surrounding traffic and buildings. Experiences obtained from this project can provide effective reference for similar cases.