When traditional ground support techniques aren't enough – Chemical injections can solve complex problems

Abstract Broken and jointed ground is extremely hazardous and requires unique stabilization techniques to protect workers and critical entries. Bolting techniques, even the most advanced pre-load to create roof compression, can leave large gaps of unconfined and separated roof. This roof can also be susceptible to water inflows which only exacerbate the support problem. These types of conditions existed on long-term development main entry accessing several future longwall panels. The geotechnical assessment identified well defined jointing systems that also permitted water to flow between the roof separations, which “lubricated” the roof material and minimized any frictional advantages. Chemical injections of polyurethane materials, Minova Carbopur WS, was placed beyond the bolted horizon to move the water to the rib lines and reinforce the fractured and broken roof. The injection materials permitted the effective use of bolting patterns and helped ensure long-term stability of critical entries. The paper describes the evaluation techniques, design patterns, basis for chemical selection and application, and results and recommendations.