ABSTRACTIn this year, landslide disaster such as embankment slide, bankslide, or buried of soil (trash) often occurs. All of them begin with asimple problem, that is infiltration of rain water (or other) into soil causingthe decrease of shear strength, finally passed the limit of landslide safetyfactor F, so landslide occurs. The research tries to know the behavior ofclayey-mud soil with several ratio of clay content and several watercontent ratio to find out how much clay content and water content (w)may induce soil collapse.This experiment research was conducted in the soil laboratoryUNY using clayey-mud soil from Klaten which has been conditioned inseveral clay content (00/0-400/0) and water content w (20%-30%) andthen direct shear tests were applied. The product of this experimentwere: cohesion (c), internal soil shear angle, phi (25% watercontent,interlocking (cohesion) would constant. The maximum cohesion(interlocking)(0.09 kg/cm2) reaches at 20% of water content (2) Forpure mud soil, increasing of water content until 30% would increase of 25%, the value of