Assessment of Fractures in Excavation Damaged Zone around Roadways of an Iron Mine Using Optical Televiewer Detecting Method

Abstract

The properties of the excavation damaged zone (EDZ) are critical to the stability of the surrounding rock masses of the chamber, roadway, and dam, and fractures in the EDZ also affect the properties of the EDZ. In this paper, the fractures in the EDZ of an underground iron mine roadway were tested using borehole television (BTV). The results revealed that the better the grade of rock mass is, the less broken it was after excavation. An assessment method based on BTV image data has been proposed for evaluating the roadway’s surrounding rock. This method uses the borehole image data to classify the excavated surrounding rock into intact rock mass, joint zone, fracture zone, and broken zone based on the condition of rock and the distribution of fractures within the rock mass. A relatively complete joint zone caused by the construction of the drill and blast method was found by using this method, and the support measures should ensure that this joint zone is not damaged. The method provides a better basis for improving the support design, according to which the improved support measures have achieved a better support effect and economic benefits.