Centrifuge model tests on excavation in Shanghai clay using in-flight excavation tools

With the development of urbanization, more and more infrastructures have been constructed in Shanghai, and excavations in the field tend to be deeper and closer to adjacent structures. As Shanghai clay is very soft and highly compressible with high water content and low strength, ground deformation and wall deflection are of prime concerns to engineers in deep excavations constructed in Shanghai. Aseries of small-scale centrifuge model tests using reconstituted Shanghai soft clay have been carried out to simulate the construction sequence of multi-strutted deep excavation. A new testing device has been applied to simulate the whole process of excavation, in which a scraper moves freely in both horizontal and vertical directions to excavate the soils and the bracing system is modelled by multiple pairs of struts powered by air pressure. Ground surface settlement, wall displacement and lateral earth pressure were monitored during the excavation.