Study on Deformation Law of Crossing Layer Drilling Superimposed Floor Roadway

ABSTRACT Floor extraction roadway crossing layer drilling is a pivotal strategy for gas control in areas prone to coal and gas outbursts. However, this method often fails due to overburden pressure and mining stress, causing floor deformation and drilling blockage. To solve the problem for extracting gas of crossing coal layer drilling in the floor roadway, uniaxial compression tests on perforated specimens was carried out. And the plastic zone failure of crossing layer drilling was analyzed through numerical simulations in FLAC 3D with customized command flow. The study finds that drilling angle, drilling section, and coal‐rock interface most affect borehole deformation. Hole sections show decreasing compressive strength: borehole mouth > borehole body > borehole bottom. The present investigation reveals that low dip angle drilling is particularly susceptible to complications such as borehole blockage and collapse. It is recommended to implement protective measures for low dip angle drilling.