Evaluation of pillar-roof interface and its effect on pillar stability in Rio Deserto coal mine #101
Viktor Lönnies1; Tristan Jones1; André C. Zingano2
1 Luleå University of Technology; 2 UFRGS
Baixar PDF doi:10.20906/CPS/CBCM2017-0033
Resumo
Evaluation of pillar-roof interface and its effect on pillar stability in Rio Deserto coal mine #101 Viktor Lönnies1 - M.Sc. Student Tristan Jones1 - Senior lecturer André C. Zingano2 - Senior lecturer 1Luleå University of Technology, 2Universidade Federal do Rio Grande do Sul viklnn-1@student.ltu.se; tristan.jones@ltu.se; andrezin@ufrgs.br Keywords: Interface, pillar, coal, numerical modelling Rio Desertos coal mine #101 is currently mining the well-known Barro Branco coal seam in the state of Santa Catarina. The mine is currently experiencing problems related to the pillars in one of their slightly-inclined panels. Inspections have shown that several pillars have developed damages on the down-slope side, tending to occur in the upper corner. The inspections also revealed a very thin and soft clay layer located between the pillar and the roof. It is believed that the clay interface is affecting the pillar strength and which caused the damages. Evaluations of the clay layers' influence on the pillar stability is conducted by numerical modelling using FLAC. Initially a calibration of the model is made using information from extensometers installed by mine survey. Afterwards, the combination of different sets of interface and coal-strength values were evaluated while observing the modelled pillar behavior. The results indicate that with a very small shear movement (1-4 mm) along the interface, the developed pillar damages are almost symmetrical on both the up-slope and down-slope sides. Structures in the coal, such as joints and cleats, can contribute to non-symmetrical damages, but not enough to make the model perfectly match field observations. Furthermore, the results show that the observed damages are best reproduced when the shear movement between the roof and pillar is forced to ~15 mm. Shearing along the interface is therefore believed to be the main mechanism behind the pillar damages. The forced shearing can potentially be explained by factors not considered in the model such as horizontal st
Palavras-chave: Interface; Pillar; Numerical modelling; Coal