Towards an Efficient iPad-Based LiDAR Structural Mapping Methodology for Underground Mines

Abstract

ABSTRACT Structurally controlled instability is a major failure mechanism in underground hard rock mines. From a design perspective, it is important to effectively define the structural regime to assess the potential rockmass failure mechanisms. In a mining context, detailed structural mapping can be challenging due to the large extent of the underground excavations and limited access to the rock face. Structural mapping can be performed using manual mapping approaches or remote sensing techniques. Fixed photogrammetry and terrestrial laser scanning have been used in the past for rockmass characterization. However, these approaches are often time consuming and consequently not widely used in practice for structural mapping in underground mines. Mobile LiDAR systems have been increasingly used for 3D mapping applications. However, it has not been demonstrated that they can be effectively used as mapping tool in the context of a mine in production. This paper presents the results from an underground mapping campaign using a mobile LiDAR scanner approach, an iPad Pro 5th generation, in an arctic mine in northern Canada. A comparison between the results from the developed methodology and manual structural mapping demonstrated significant advantages and remaining challenges in the use of the mobile LiDAR approach for rockmass characterization. INTRODUCTION In underground hard rock mines, rock mass instability poses a serious hazard to the safety of personnel and equipment. The structural regime largely controls the mechanical behaviour of jointed rock masses around the underground excavations. Under low-stress conditions, gravity failure of large blocks formed by the presence of rock discontinuities can be a significant hazard. Figure 1 shows a rehabilitated section in the ramp of an operating hard rock mine after a structurally controlled fall of ground in the back. Under these conditions, it is essential to consider the complex structural regime in the design and support of underground excavations. It is, therefore, necessary to adequately characterize the structures in the rock mass using a combination of qualitative observations and quantitative measurements.