Research On The Detection Of Ground Penetrating Radar In Guizhou Road Subgrade Concealed Soil Cave

The subgrade is the foundation of the road.The quality of the subgrade is an important factor affecting the safe operation of the road.With the development of traffic and transportation all over the country,the quality of the road subgrade has also been paid more and more attention.The underground karst caves and goaf in Guizhou are widely distributed,and the road construction will inevitably cross the karst cave,the goaf and the urban underground pipe culvert and so on.In the road subgrade soil which is built above them,it is very easy to form the soil cave.The existence of soil cave greatly reduces the bearing capacity of roadbed and poses a great threat to the safe operation of vehicles.Therefore,detecting hidden holes in road subgrade is very important for road safety operation.As a fast,efficient and nondestructive geophysical method,GPR has been widely used to detect subgrade hidden diseases.It is one of the most effective means to detect hidden soil holes in large area subgrade.On the basis of summarizing the basic morphological characteristics of buried soil holes in Guizhou road subgrade,this paper simulated the critical collapse conditions of two typical cavities of typical wells and columns by using the FLAC3 D numerical simulation software.Based on the basic principle of GPR,the subgrade hidden soil cave,which threatens the safety of road traffic safety,is carried out by the forward numerical simulation,the forward physical simulation experiment and the application research.The main results obtained are as follows:(1)By collecting the previous scholars' research on Guizhou soil cave,the characteristics and morphological characteristics of the common soil cave in Guizhou are summarized,and the soil cave morphology is summed up into a typical cylindrical and well shape,and then the critical conditions of the cave collapse are simulated,and the buried depth and geometry of two different shapes of soil cave collapse are obtained.(2)According to the morphological characteristics of the hidden soil holes in the road subgrade in Guizhou,two kinds of common soil holes are simulated by the GprMax forward numerical simulation software.Analyzed the numerical simulation image characteristics of the soil holes with different shapes,different geometric sizes and different buried depths,and pointed out the buried depth of the soil holes which can be detected by different frequency antennas.(3)According to the research result of the critical collapse condition of the hidden soil cave in Guizhou road subgrade,the physical simulation experiment scheme is designed for the soil cave which may cause the pavement collapse,and the physical simulation experiment is done by searching the underground pipe which is similar to the design model,Analyzed the characteristics of GPR images with different frequency antennas in the same model under the same condition.(4)In combination with the application examples of road subgrade detection in Guizhou,The results of the test are in accord with the actual situation.It is proved that the GPR can detect the hidden soil cave in the road subgrade which may cause the ground collapse.