Model tests and new progress of pile response due to underground excavations

The disaster from the unloading effects induced by underground excavations has always been one of the high-concern issues. In recent years, a series of ground deformation, pile foundation tilt, or building collapse cases have taken place in China, and sometimes they even threaten people's lives and property. The imperfection of the conventional model tests for simulating underground excavations is introduced, and the typical experimental test methods and test devices including small-scale and centrifuge models corresponding to excavation of foundation pit and tunneling in the past two decades are briefly compared. In this study, a new testing apparatus for pile load response undergoing underground excavations is proposed, and its design principles and technical characteristics are analyzed. Using the test boxes, the studies on the lateral pile response to adjacent excavation and the blocking effect of a barrier on the flow of groundwater are conducted. Finally, some suggestions and prospects about the future study on unloading piles are put forward.