The ground soils below the building foundation loosened heavily due tounsuitable construction. It threatened the safety of near structures and safely operating of gaspiping or heat piping. Based on tlie understanding and studying to the causes and the propertiesof tbe failnre, surveying by geological radar is used to certain the degree and the region of theloosened soil. Remedial measures are adopted in time to ensure tlie excavating of the foulldationand tLe safety of structures.