Ground penetrating radar(GPR) rapidly provides high resolution data on soil water content.This paper presents a comprehensive review of the basic principle of GPR and four methods for soil water content assessment,which are multi-offset methods,common offset methods,borehole GPR methods,and GPR signal attribute methods.For each of these four methods,we discuss the basic principles,illustrate the quality of the data with practical examples,and discuss the possibilities,limitations and errors.

The basic theories of ground penetrating radar(GPR) in the geology prediction for tunnel are introduced;the working process of GPR probing is summarized systematically.Take Fuzhou expressway for example,using the EKKO IV radar system combined with geological sketch method to forecast about rock structure.The results show that it can effectively avoid the narrow space,lots of interfere factors and other unfavorable conditions in tunnel,and can detect the adverse geological conditions with high resolution.The accurate prediction guarantees safe production,accelerates job schedule and acquires favorable benefit.This paper will no doubt benefit the extension of GPR in the geology prediction for tunnel excavating.