Peak particle velocity as an indicator of dynamic load exerted on the support of underground workings

Rock mass vibrations directly affecting the roof support in roadways and load on the support were continuously measured for 78 days in the deep seismic-prone coal mine Bobrek. The mine tremor of seismic energy E = 3E5 J (local magnitude, M L =2) and E = 8E3 J (local magnitude, M L = 1.1) located close to the tested roof support induced peak particle velocity weighted over 25 Hz, PPV w = 0.110 m/s and PPV w = 0.046 m/s. During the vibrations, an increase in vertical load of 82 kN and of 100 kN under the arch support was recorded. During vibrations induced by the other 395 seismic events, very low values of PPV W were recorded, i.e., less than 30 mm/s, and no significant increase in load was recorded under the arch support. However, the measurements showed that seismic events can cause a significant increase in load on the support, especially when the mine workings are located in the near seismic wave field, in which the parameters of peak particle velocity weighted over 25 Hz (PPV W ) reach very high values. The influence of wave motion, which is caused by a seismic event, on the steel arch support was also analyzed with FLAC software numerical modeling and showed an important increase in the calculated load on the arch steel support.