Experimental study on GPR model for artificial freezing projects

It is effective to detect the thickness and lacuna of artificial freezing walls by means of the ground penetrating radarGPR). Based on the physical model tests, the similarity criteria of GPR exploration are derived for artificial freezing projects, which have clear physical meanness and can be employed to explain the relationship of the propagation time and amplitude of GPR signals between the model and the prototype. According to the electromagnetic properties of freezing soils with different frequencies, the similar criterion is a contradictory one in GPR model for the artificial freezing projects. It is deduced that in AFE the travel time and characters of anomalies in GPR profiles are similar to those of the prototypes, while the amplitude of GPR signals will be much stronger than that of the prototypes. Through model tests and field explorations, the characteristics of typical anomalies in AFE, such as freezing pipe and defects, are obtained and reported. It is found that they play an important role in the construction of the connecting passage of Shanghai Yangtze River Tunnel. The research findings have an important theoretical value for the GPR experimental study and can be used in artificial freezing projects and engineering construction in permafrost regions.