Geotechnical characterization and rockfall simulation using remote mapping. A case of Carnsew Quarry in Penryn, Cornwall (UK)

Remote mapping involves obtaining rock slope data using laser scanning. The data is a collection of 3-D coordinates and typically includes intensity and colour information about objects present in the 3-D scene. Several software analyses were undertaken ranging from Split FX to stereographic projection to make sense of the data obtained by the method. Remote mapping has proved to be a very important and effective tool in terms of obtaining geotechnical data for observation and analysis. The rock slope section under consideration (Carnsew quarry) is an example of the need for remote mapping since hand mapping could not be achieved on the slope because of the safety hazard due to the steepness of the slope. Analysis of the slope data by kinematic analysis in Dips (stereographic projection) reveals a serious risk of failure that could result from either wedge or flexural toppling or both failure mechanisms. It is from these failure mechanisms that rockfall could originate from (through rocfall software analysis). This is true because of the steepness of the slope specifically the section above the haul road. The risk of rockfall possess a severe hazard on safety of workforce on the quarry mine. The height and energy possessed by rocks falling could also damage equipment on the mine. It was therefore, recommended that operations on this section of the slope be suspended for further geotechnical analysis to be done. Specifically, a cost benefit analysis was suggested to compare the cost of maintaining or stabilising the slope (control of wedge or flexural failure and rockfall) against the value of the slope section in terms of productivity.