Special Case on Landslide in Balikpapan, Indonesia Viewed from Crack Soil Approach

This research aims to determine the impact of cracked soil and its corresponding variations on slope stability within two distinct areas exhibiting diverse topographic conditions, both of which have previously encountered failure in Karang Joang, Balikpapan. A coupled program, such as SEEP/W and SLOPE/W was applied to access the influence of rainfall on slope stability, while existing soil data and GEO5 were utilized to evaluate the effect of changes in soil parameters caused by the cracks. The analysis assumed the presence of cracks with parameters Cu = 0 kPa and ϕ = 18°–30° in all soil layers, producing a safety factor that more accurately reflected the real landslide conditions in the field. The results showed that the slopes in both research locations remained highly stable when analyzed with soil parameters obtained from conventional tests such as N-SPT, CPTu, and laboratory assessments, despite the occurrence of landslides. This finding was attributed to the inability of conventional soil tests to detect cracks and variations in its parameters. The topography of the area influenced the hydrogeological conditions and the groundwater levels, which contributed to the occurrence of landslides.