A NARROW SPACED SEISMIC REFRACTION SURVEY FOR A LOOSENED ROCK-MASS IN LANDSLIDE AREA

This paper describes the result of a narrow spaced seismic refraction survey for a loosened rockmass adjacent to landslide in a preparing stage of dam construction in Japan. We conducted the narrow spaced seismic refraction survey for a loosened rock-mass of landslide in two dam sites. A narrow spaced seismic refraction survey originates form short interval geophone setting and high sampling rate. The rock-mass adjacent to rock-mass failure was fractured and showed plastic deformation. Geophones in this seismic refraction survey were put in a gallery excavated in loosened rock-mass ten times as narrowly as that of a conventional method. High rate sampling and narrowing the intervals of geophones made it possible to delineate a loosened rock-mass of landslide.