STUDY ON STOPE STABILITY USING DISPLACEMENT MONITORING DATA

• Main Author: Noor Hakim, Romla
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/65150
• Institution: Institut Teknologi Bandung

The study is conducted at North Sill drift Cross-Cut 3B level 1061 PT Cibaliung Sumberdaya Underground Gold Mining which apply cut and fill method. The research object is observation of the displacement surrounding perimeter of active sill drift that have been considered suffering a huge load due to the condition of above level which partially have been already backfilled and reinforced at the floor by concrete and partially still cavity. The walls and roof of the observed sill drift has been supported by a combination of friction bolt (split set), weld mesh and shotecrete. Commonly, convergence meter is one of the most suitable instruments used in underground mining for the deformation monitoring system. Convergence meter provides a higher accuracy of measurement, however some difficulties will be encountered if the measurement is conducted in an active large stope. Along with the development of technology in surveying, therefore, in this study the displacement of stope perimeter is observed by reflectorless total station unit. In this research area, in situ stress condition is still unknown, therefore before used for analyzing the opening stability obtained the monitoring data will be used for determining the stress condition of surrounding the openings by trial and error back analysis method. The determined insitu stresses are then used in the simulation for evaluating the stability of the existing drift and the next excavation drifts. The results of the analysis at monitoring points, the cumulative displacement is average 200mm (>75mm), and displacement rate is average 24mm/days (>1mm/days), therefore it can be classified as unstable condition according to the Cording criteria. Eventhough along the monitoring activy, the observed sill drift condition is in stable condition. Its means that the applied rock supporting system is strong enough. From the simulation result, excavation Plan number 1 (3A XC 1056), has the horizontal displacement more than 8mm and the vertical displacement less than 8mm, therefore some modification of rock support is necessary. Excavation Plan number 2 (XC 3B1 1061), has the horizontal displacement in normal conditions but abnormal in vertical displacement, so it is necessary to modify the rock support at the left corner of the roof position.