The research presented in this thesis results from efforts to evaluate current design methodologies for safety benches in surface aggregate quarries. Proper bench design is important for preventing rockfall related accidents and injuries without wasting the reserves held in the benches. An in depth analysis has been performed using the results from 230 rockfall tests conducted at two surface quarries. The goal of this project is to give practitioners the tools they need for improved bench design.
Principal Components and Cluster Analysis, techniques not previously applied to rockfall investigations, have been performed on the test data. The results indicate that both are valid analytical methods which show that the factors affecting the rollout distance of a rock are wall configuration, rock dimensions, and rock energy. The test results were then compared to the Ritchie Criteria, Modified Ritchie Criterion, Ryan and Pryor Criterion, Oregon Department of Transportation design charts, and RocFall computer simulations.
Analysis shows that the lognormal distribution curves fitted to the test data provide an excellent yet quick design reference. The recommended design method is computer simulation using RocFall because of the ease of simulation and the site specific nature of the program. For the two quarries studied, RocFall analysis showed that 20 ft benches with a 4 ft berm will hold over 95% of rockfalls, a design supported by the field testing. Conducting site-specific rockfall testing is also recommended to obtain realistic input parameters for the simulations and to provide design justification to regulatory agencies.
