Practical experiences from application of remedial measures for slopes in gypsum rock masses

Summary

Abstract

During the last decade, the aspect of with rockfalls occurred on the steep slopes along the Macedonian road network, becomes a serious problem from safety, economic and social aspects. That produced delayed in a transport of goods, temporary blockage of traffic and some social influences that produced direct and indirect costs for affected areas. In a frame of this study, one example is presented for a case of very high slope constructed in jointed gypsum rock mass at the regional road from Marovo to town Debar. Based on the identified potentially unstable rock masses and analyses presented in design documents, some specifics for application of protection measures. The trajectories, impact energy and the height of bouncing for defined slope geometry and rockfall blocks characteristics are measured during the work. All the data are collected during application of special techniques for protection from rockfalls at a slope with a height more than 70 meters. Several protection measure approaches were adopted: prevention of rockfalls by removing potentially unstable rock mass with scaling using alpinist techniques, up to installing of rock bolts and rockfall protection barriers. The direct observations of rockfall trajectories from a phase of scaling are used to compare values from design documents with observed values. The findings are used to calibrate the values of coefficient of restitution used in rockfall analyses. Based on that, some logical zone for this coefficient for gypsum rock masses is suggested for further analyses.