Previous classification of rock mass surrounding underground excavations and rock support design using block models.

Abstract

The creation of tridimensional models that represent the quality and geomechan- ical characteristics of the rock mass to be excavated can be made by using spatial inter- polation techniques. The aim of this research is to improve the safety in underground

activities, as well as to spread and popularize the use of spatial interpolation methods

to represent both the spatial continuity of the quality of the rock mass and the geome- chanical variables through geostatistical methods. This article presents and demon- strates the viability of using Q-System block models estimated from the borehole data

for previous classification of the rock mass surrounding the underground excavation and rock support design. The block model for the support design of galleries is justified because it allows to previously forecast the kind and quantity of support necessary for

the stability of the excavation, as well as the costs with these devices, besides increas- ing the safety in the operations. Techniques of indicator kriging and ordinary kriging

were used to build the Q-System index block model. The model was validated through the techniques of visual inspection and cross validation. The data used in this study were collected from the geotechnical description of 39 borehole core samples with a total measurement of 4,015 meters in Fazenda Brasileiro Mine, located in the town of Teofilândia, Bahia State, Brazil.