In situ stress determination using the under-excavation technique—II. Applications

Abstract In Part I of this paper, the theoretical foundation for the under-excavation technique (UET) was presented and it was shown how the in situ stress state could be determined from strain measurements using CSIRO, CSIR or other borehole strain cells in conjunction with displacement measurements from convergence gauges, extensometers, inclinometers and tiltmeters. In this paper, applications of the UET are presented. In the first example, the far field stress state is determined for the case of a vent raise. The second example is for the case of a drift, excavated by standard blasting techniques. The results presented in this report illustrate that although the UET has limitations, just as all other in situ stress measurement methods, it represents an attractive alternative stress measurement method. The UET has the distinct advantage of sufficient redundancy in the data to assess the accuracy of the stress predictions, without prior knowledge of the in situ stress state.