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 l...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.展开更多
Fiber-reinforced spayed concrete has been used for several years in civil and tunneling operations.Research conducted to reduce cure times and increase compressive and flexural strengths resulted in the development of...Fiber-reinforced spayed concrete has been used for several years in civil and tunneling operations.Research conducted to reduce cure times and increase compressive and flexural strengths resulted in the development of Tekcrete Fast~, a cementitious product capable of obtaining 41 MPa compressive strength and 8 MPa flexural strength in only 3 h and reaching 7 d strengths of 62 and 11.7 MPa, respectively.A single bag product that uses conventional shotcrete and gunite application systems makes it a natural crossover product for mining applications.The discovery of incredible adhesion properties and high resistance to chloride permeability helps ensure long-term stability and increases the ease of application.Project results from Disaster City~ in Texas and the application for rehabilitating a coal mine belt entry are presented.The case study illustrates the effectiveness of the product in stabilizing a coal mine beltway and adjacent cross-cuts that were subjected to progressive sloughage due to humidity and cyclical loading.展开更多
文摘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.
文摘Fiber-reinforced spayed concrete has been used for several years in civil and tunneling operations.Research conducted to reduce cure times and increase compressive and flexural strengths resulted in the development of Tekcrete Fast~, a cementitious product capable of obtaining 41 MPa compressive strength and 8 MPa flexural strength in only 3 h and reaching 7 d strengths of 62 and 11.7 MPa, respectively.A single bag product that uses conventional shotcrete and gunite application systems makes it a natural crossover product for mining applications.The discovery of incredible adhesion properties and high resistance to chloride permeability helps ensure long-term stability and increases the ease of application.Project results from Disaster City~ in Texas and the application for rehabilitating a coal mine belt entry are presented.The case study illustrates the effectiveness of the product in stabilizing a coal mine beltway and adjacent cross-cuts that were subjected to progressive sloughage due to humidity and cyclical loading.
