In-Flight Simulation of the Excavation of Foundation Pit in Centrifuge Model Tests

摘要

It is of great importance to simulate the excavation of foundation pits in centrifuge model tests. A new device was designed with new principles based on the understanding of the stress field in the soil base before and after excavation. A loading system was used to replace the excavated soil so that the appropriate self-weight stress state could be achieved with an increase of centrifugal acceleration before excavation. The compensation unit and the confining structure were simultaneously removed using the loading unit to simulate the excavation with accuracy. The device was made using a series of new structures for a high degree of automation and good accuracy in simulating the excavation of foundation pits. This device can be used to test a wide range of pit foundations and supporting structures. All of the components of the device were carefully designed to minimize their size and mass with a good control on the deformation of themselves. The device was confirmed to be effective in simulating the excavation of foundation pits at the 50-g level by a series of centrifuge model tests. The true paths of the stress and deformation of the foundation pit could be reasonably simulated in the centrifuge model tests, which cannot be captured by the traditional method in which the excavation was conducted previously at the 1-g level. The traditional method underestimates the earth pressures and the deformation of the soil due to the excavation of the foundation pit according to the comparison tests.