Deformational behaviour of roadways in soft rocks in underground coal mines and principles for stability control

Following a brief introduction to the nature of a roadway excavated in soft rocks in underground coal mines, six characteristics featuring its deformational behaviour are formulated and illustrated extensively with data collected over decades. The characteristics are: (1) a high rate of rapid deformation in response to ground pressure redistribution: (2) evident rheological deformation; (3) high sensitivity to stress changes; (4) high sensitivity to water invasion; (5) deformation occurring in all directions of the roadway cross section; and (6) a predominant floor heave component in the roof-to-floor convergence. In view of the nature of an underground roadway located in soft strata, principles for controlling the roadway stability both effectively and economically for the whole service life span are specified. A case study is also presented in order to demonstrate the application of the outlined principles for the stability control of roadways excavated in such soft rocks using a multiple support system with joints. (C) 2000 Elsevier Science Ltd. All rights reserved.