A seismic method utilizing surface waves of the Rayleigh type, called the Spectral-Analysis-of-Surface-Waves (SASW) method has been developed for determining the shear wave velocity and shear modules profiles of geotechnical site. All SASW field tests are performed at small-strain levels (
The surface wave prospecting method that conducted on the ground surface is one of the non-destructive testing methods. The penetrating depth of the surface wave depends on the frequency of the surface wave. By the phase velocity of the difference frequency of the surface wave, the S wave velocity structure of the sublayers could be developed. The SASW and the MASW method coud be attributed to the depth of less than several tens meters. The procedure of the surfave wave prospecting is as follows： 1. To layout two or many receivers on the site and conduct the Rayleigh wave measurement, 2.Dispersion curve analysis, 3. Inversion analysis of the S wave velocity structure. The surface wave prospecting method could be applied to the nondestructive testing of the RC structure in smaller scale, and S wave velocity structure down to 50m in larger scale.
The application of two non-destructive testing methods, namely seismic method and ground penetration radar method, on the performance confirmation of the existing geotechnical facilities were introduced in this paper. The structure integrity and strength of the diaphragm wall, retaining wall, and airport taxiway were successfully examined which provides solid evidence on the superiority of non-destructive testing method.
The Lisan land slide area consists of many sliding blocks within an area of approximately 230 ha. Because of a reservoir and island crossing highways located in this area, the government initiated tremendous efforts on stabilizing the area since a slide occurred in April, 1990. An automatic system was set up for monitoring the ground movement and ground water table variation in order to evaluate the effect of engineering remedial works. The system has been working for some time under a stable condition. This paper describes the system, including its planning, operation, and utilization of the data obtained from this system.
Ground Penetrating Radar (GPR) is one of the non-destructive inspection methods widely applied in civil engineering structure since it has many advantages, such as fast and easy operation and low cost. In addition, GPR provides final image with very good resolution and the interpretation become reliable. This paper introduces some cases study of civil engineering application. The results successfully indicate the superiority of GPR method and worth for further study.
The drilling is a fundamental method to obtain reliable underground geological information. However, the drilling can only provide a point information under the surface. We need other methods to extend the drill results to two or three dimensions. The geophysical method is no doubt the best one to choose. This paper provides two cases to explain how to use reflection seismic profiles to assist the drilling. One is the case of the Chelungpu fault which was induced by the 1999 Chi-Chi earthquake (ML=7.4) and the other is the San-I fault. The results seem quite encouraging. With proper operations, the geophysical methods should be able to cooperate with the drilling, and produce more detailed underground geological information.