Two distinctive shear strain modes for pile-soil-tunnelling interaction in a granular mass

There are many high-rise buildings in urban areas, which are normally supported by piled foundations. Consequently, a major concern for geotechnical engineers is the construction of a tunnel adjacent to the piled foundations, since ground behaviour between an existing loaded pile and tunnelling has not been understood well so far, particularly for granular soils rather than clay soils. In order to figure out such complicated ground behaviour, the interactive shear strain patterns are generated by two-dimensional laboratory model tests and finite element analyses (FEA). For the model testing, a multi-sized aluminium rod mixture considered as a continuum granular mass and close range photogrammetric technique for obtaining displacement data within the rods are introduced. Two distinctive shear strain modes, viz. connective and isolated modes, are presented through the comparison of the model tests and FEA according to the pile tip locations.