Analisis Failure Time Menggunakan Data GPS Geodetic dengan Metode Inverse Velocity pada Lereng Disposal HW 123 South Tutupan PT. Adaro Indonesia, Kalimantan Selatan

PT. Adaro Indonesia is one of the largest coal companies in Indonesia with one of its production operations located in the southern tutupan pit area. This research was conducted to analyze the failure time that occurred in the outpit dump area of the southern tutupan pit. There is a development pattern behavior that occurs on the slope, namely linear reaching behavior, onset of failure (OOF), progressive reaching behavior, failure to post-failure reaching behavior. From the deformation, the slope movement status of the three GPS used (G21, G73, and G76) is known, namely safe conditions are at a speed of ˂ 50 mm, careful conditions are at a speed of 50 mm - 85 mm, alert conditions are at a speed of 85 mm - 105 mm, and dangerous conditions are at a speed of ˃ 105 mm. Furthermore, a back analysis of landslides was carried out from deformation data with different time windows. Landslide predictions with time windows (1 hour, 3 hours, 12 hours) each occurred on the dates (February 9, February 10, February 10) and time windows (1 day, 3 days, 6 days) occurred on the dates (February 11, February 12, February 14). So the 3-hour time window is appropriate. The 3-hour time window data will be used to carry out forward analysis of landslides based on deformation data taken from March 14 - April 30. From the results of the deformation, velocity, and inverse velocity calculations, the predicted time of the landslide occurred on June 12. Furthermore, the engineer can carry out an evacuation where the evacuation time is 6 hours before the landslide occurs.