High strength reinforced concrete drilling shaft linings have been adopted to solve the difficult problem of supporting coal drilling shafts penetrating through thick top soils. Through model experiments the stress an...High strength reinforced concrete drilling shaft linings have been adopted to solve the difficult problem of supporting coal drilling shafts penetrating through thick top soils. Through model experiments the stress and strength of such shaft linings are studied. The test results indicate that the load beating capacity of the shaft lining is very high and that the main factors affecting the load bearing capacity are the concrete strength, the ratio of lining thickness to inner radius and the reinforcement ratio. Based on the limit equilibrium conditions and the strength theory of concrete under multi-axial compressive stressed state, a formula for calculating the load-beating capacity of a high strength reinforced concrete shaft lining was obtained. Because the concrete in a shaft lining is in a multi-axial compressive stress state the compressive strength increases to a great extent compared to uni-axial loading. Based on experiment a formula for the gain factor in compressive strength was obtained： it can be used in the structural design of the shaft lining. These results have provided a basis for sound engineering practice when designing this kind of shaft lining structure.展开更多
Concentrations of eleven heavy metals （AI, Cd, Co, Cu, Cr, Fe, Mn, Mo, Ni, Pb and Zn） and pH determination in water from nine spade-sunk wells of 2-15 meter depth, five drilled wells of 30-72 meter depth, and two wa...Concentrations of eleven heavy metals （AI, Cd, Co, Cu, Cr, Fe, Mn, Mo, Ni, Pb and Zn） and pH determination in water from nine spade-sunk wells of 2-15 meter depth, five drilled wells of 30-72 meter depth, and two water supply faucets in the Kipushi mining town, south-east of the Democratic Republic of Congo, were investigated from February to July 2011. The results were compared with the World Health Organization （WHO） drinking water pH and heavy metal guidelines. Mean concentrations of Pb in water from four spade-sunk wells and three drilled wells, those of A1 and Fe in water from four and two spade-sunk wells, and those of Cd in water from four drilled wells were higher than the WHO drinking water maximum permissible contaminant limits of 0.01 mg/L, 0.2 mg/L, 0.3 mg/L and 0.003 mg/L respectively, probably due to the mining activities carried out in Kipushi for about 90 years. The pH mean values of water from five spade-sunk wells and three drilled wells were lower than the WHO drinking water pH optimum of 6.5-9.5, suggesting that the water from those eight wells was not conform to the chemical quality of water for human consumption.展开更多
The information extracted from monitoring of rotary blasthole drills helps to optimize the overall mining operation. Rock hardness, drillability, blastability and specific energy of drilling are examples of parameters...The information extracted from monitoring of rotary blasthole drills helps to optimize the overall mining operation. Rock hardness, drillability, blastability and specific energy of drilling are examples of parameters that have been estimated in the past using measurement while drilling techniques. In order to be able to properly utilize measurement while drilling techniques, it is important to properly collect, analyze and interpret extracted data. This paper deals with processing of measurement while drilling data such as rate of penetration, rotary speed, rotary torque and pulldown force collected from rotary blasthole drills.Different methods are discussed to calculate a true rate of penetration which is the most important monitored drill variable for use in rock mass characterization. Then specific energy of drilling is defined and calculated based on electrical and mechanical inputs and the results are compared. The results show that specific energy of drilling can be estimated using the drill's primary drive systems' electrical responses with good accuracy when compared to values based on mechanical inputs.展开更多
基金Project 050440502 supported by the Natural Science Foundation of Anhui Province
文摘High strength reinforced concrete drilling shaft linings have been adopted to solve the difficult problem of supporting coal drilling shafts penetrating through thick top soils. Through model experiments the stress and strength of such shaft linings are studied. The test results indicate that the load beating capacity of the shaft lining is very high and that the main factors affecting the load bearing capacity are the concrete strength, the ratio of lining thickness to inner radius and the reinforcement ratio. Based on the limit equilibrium conditions and the strength theory of concrete under multi-axial compressive stressed state, a formula for calculating the load-beating capacity of a high strength reinforced concrete shaft lining was obtained. Because the concrete in a shaft lining is in a multi-axial compressive stress state the compressive strength increases to a great extent compared to uni-axial loading. Based on experiment a formula for the gain factor in compressive strength was obtained： it can be used in the structural design of the shaft lining. These results have provided a basis for sound engineering practice when designing this kind of shaft lining structure.
文摘Concentrations of eleven heavy metals （AI, Cd, Co, Cu, Cr, Fe, Mn, Mo, Ni, Pb and Zn） and pH determination in water from nine spade-sunk wells of 2-15 meter depth, five drilled wells of 30-72 meter depth, and two water supply faucets in the Kipushi mining town, south-east of the Democratic Republic of Congo, were investigated from February to July 2011. The results were compared with the World Health Organization （WHO） drinking water pH and heavy metal guidelines. Mean concentrations of Pb in water from four spade-sunk wells and three drilled wells, those of A1 and Fe in water from four and two spade-sunk wells, and those of Cd in water from four drilled wells were higher than the WHO drinking water maximum permissible contaminant limits of 0.01 mg/L, 0.2 mg/L, 0.3 mg/L and 0.003 mg/L respectively, probably due to the mining activities carried out in Kipushi for about 90 years. The pH mean values of water from five spade-sunk wells and three drilled wells were lower than the WHO drinking water pH optimum of 6.5-9.5, suggesting that the water from those eight wells was not conform to the chemical quality of water for human consumption.
文摘The information extracted from monitoring of rotary blasthole drills helps to optimize the overall mining operation. Rock hardness, drillability, blastability and specific energy of drilling are examples of parameters that have been estimated in the past using measurement while drilling techniques. In order to be able to properly utilize measurement while drilling techniques, it is important to properly collect, analyze and interpret extracted data. This paper deals with processing of measurement while drilling data such as rate of penetration, rotary speed, rotary torque and pulldown force collected from rotary blasthole drills.Different methods are discussed to calculate a true rate of penetration which is the most important monitored drill variable for use in rock mass characterization. Then specific energy of drilling is defined and calculated based on electrical and mechanical inputs and the results are compared. The results show that specific energy of drilling can be estimated using the drill's primary drive systems' electrical responses with good accuracy when compared to values based on mechanical inputs.
