Abstract: Electromagnetic CT was first used for detecting grouting effect of Karst roadbed.According to different types of Karst,9 parts of the typical karst test segments and 60 test sections were selected.Tests were carried on separately for each section before and after grouting-test.The results showed that electromagnetic CT could test the distributional pattern of Karst cave under the roadbed,bedrock fracture zone,as well as geotechnical interface.It can estimate the flow and diffusion of cement in u...