Borehole observation methods in coal and rock mass and their applications

The observation and test methods for structural planes in coal and rock mass were introduced, and the test principles, the components and characteristics of the borehole observation instruments used in underground coal mines were discussed, including the optical fiber observer, the axial borehole camera and the digital panoramic borehole camera system. The observation results and images from typical coal mines were provided to analyze the borehole formations and the distribution characteristics of structural planes. The borehole observation results were utilized in following aspects and mining engineering: evaluation of the distributions of structural planes in coal and rock masses and their integrity; the hydraulic fracturing measurements for in-situ stresses; study on roof caving and strata movement in stopes; study on the deformation and damage mechanism of rock surrounding roadways; the roadway support and reinforcement designs; the engineering quality tests and evaluation of supporting and reinforcing effects. The underground practices prove that the borehole camera and test can provide a direct, effective and fast approach to observe borehole formations and their changes, which can obtain reliable basic data for the study on underground pressure and strata control, the mining project designs and the constructions and quality tests. Finally, the existing problems were put forward, and some suggestions were given to improve the borehole observation methods.