Abstract：Landsonar method，is a new survey method that has been successfully used in shallow layer survey and geological prediction of condition before of tunnel working face. It can be used to detect the depth of relaxation zone of surrounding rock of a tunnel with a wave source induced by hammering on the surface of rock or lining. The results by landsonar method and acoustic wave measurement method with boreholes are compared，which shows that they are consistent. In the detection of the depth of relaxation zone of surrounding rock by landsonar method，the geophones are set near by the wave source point. The measuring stations are arranged in a measuring line of 2-4 m long with a distance of 20-30 cm to one another. The data of all stations in a line are treated to a time-section on that the reflection image of the boundary line of relaxation zone can be clearly differentiated. Wave velocity can be measured by refracted wave method or common center point method on surface of rock mass or lining；and the depth of the boundary line of the relaxation zone can be calculated. Landsonar is more time-saving and convenient because it does not need boreholes which are needed in acoustic wave measurement method.
