Rock slope design requires detailed knowledge of the rock joint fabric, which is the most important parameter in bench-scale analysis. Rock-fabric data for open pit slope design may be difficult to obtain because mine planning often requires design slope angles years in advance of excavation and outcrop exposure. When rockfabric data cannot be obtained from surface mapping, one of the most cost-effective alternatives to obtain these data is oriented-core drilling.

The POND Excel® spreadsheet allows determination and presentation of the attitudes of planes intersected in ‘oriented’ and ‘navigated’ diamond drillcore. Two drillcore navigation measurements (azimuth and plunge from a deviation log), and two plane-to-drillcore angular measurements (angle to core axis, and angle between orientation mark and intersection ellipse) are required to obtain a solution.

During core drilling, runs of core up to about three metres long are extracted from the core barrel. The extraction process rotates the core randomly, so that once the core is laid out in core boxes its original orientation is lost, although the orientation of the core axis is generally known. Various down-hole surveying techniques are available for this, and the common usage of 3-D modelling software has lead to holes being generally very well surveyed. <...>

Each of the following pages contains a protractor for a specific size of drill core. 

Choose the appropriate chart for the drill core size. Check the core diameter to choose the appropriate template within each core size grouping.

The protractors are in two groups: beta angle protractors and alpha/beta angle protractors. In practice I find that the beta angle protractor alone is best as it is least cluttered with lines (and alpha angles are easily measured using a protractor). <...>

• Drill core measurement procedures

• Geometrical relationships

• Using GeoCalculator to solve the geometry

• Manual stereographic plotting procedures

• Introduction to HCA wrap-around beta angle protractor templates