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Investigation of the causes of cutter roof failure in a central Pennsylvania coal mine: a case study
7?A 862264 Investigation of the causes of cutter roof failure in a central Pennsylvania coal mine: a case study
Hill. J L; Bauer. E R in: Rock Mechanics in Productivity
and Protection (Proceedings of the Twenty-Fyth Symposium on Rock Mechanics, Evanston, Illinois, 25-27 June 1984) P603-614. Pub1 New York: AIME, 1984
Massive roof failures caused by the propagation of ‘cutter’ fractures, nearly vertical cracks which break to a height above the anchor horizon or along weak bedding planes, are common in the North Appalachian Coal Basin. Research shows correlation between cutter failure and elastic dykes. Analysis of rock pressure monitoring shows the roof acts as two cantilever beams when severed by a elastic dyke. Additional roof support supplies effective reinforcement against cutter failure, but only if installed shortly after mining.
General underground storage See:862075 Radioactive waste disposal See also: 862027, 862097 862265 Study of the compaction properties of potential clay-sand buffer mixtures for use in nuclear waste disposal
participated in water-sealing and avoided ;I clamping /one The steel lining design was chosen on grounds of cconomy.ease of installation and ability to withstand grater prrssure and shaft irregularity. The completion of this shaft demonstrates the feasibility of this sinking techmquc to 011s depth. and information gathered should simplify the planning and dimensioning of future shafts. 862268 Causes of fractured freeze pipes in the Hunxe shaft and their restoration (In German and English)
Wollers, K Gluckauf VIII, N19, IO Ott 1985. P1428-1433 (gerrnan~. P429-431 (english) (paper to the Shqft Sinking ant/ Tunnelling Colloquium, Berlin, 21-22 Feb 1985)
Part of the Hunxe shaft in Germany was sunk using the ground freezing technique. When sinking through mottled sandstone at a depth of 120m. concentric cleats formed around the shaft bottom and the shaft wall bulged out and started to crack, causing freeze pipe socket joints to leak. The cause was identified as incorrect geotechnical classification of Ems Greensand as a clay marl, whereas in fact it behaved as a stiff clay. leading to high annular stress and above average wall displacements. It is emphasised that seemingly ‘harmless’ geological formations should be suitably investigated before shaft sinking. Based on information gathered during this project, suggestions are made in order to reduce costs. These concern dimensioning of the ice wall. shaft lining and radius and site specific variables.
Dixon, DA: Gray, M N; Thomas, A W
862269
Engng Geol V21. N3/4, June 1985, P247-255
Shaft sinking in waterbearing (In German and English)
Results of tests of the compaction properties of clay-sand mixtures are presented. Both swelling and non-swelling clay materials were examined. A mixture of 50% sand and 50% clay by mass appears to optimise the physical properties of the buffer. The implications of the results to the Canadian nuclear fuel waste management concept are discussed. 862266 Construction Gossow, V
of a large storage for critical
waste
Engng Geol V21, N3/4, June 1985, P349-358
Construction of a long-term storage for critical waste is described. The base impermeability layer consisted of natural clay. The method of placement and the permeability coefficients obtained are described.
non-competent
strata in China
Ma, Y: Wang. S Gluckauf VIZI. NIY, IO Ott 1985, P1434-1437 (germatt), P432-434 (english) (paper to the Shqft Sinking and TunneNing Colloquium, Berlin, 21-2-1Feb 1985 )
The most common methods of sinking shafts through waterbearing. non-competent strata in China are ground freezing and an improved drop shaft method - the mud drop shaft, with debris recovered from the standing water. Shaft boring or soil grouting are used rarely. Improvements to the freezing technique over 30 years are briefly reviewed.in particular the accuracy of freeze boreholes. the ice wall and optimisation of the freezing process. The construction and stress fields of shaft linings are discussed. For the drop shaft, work has concentrated on excavation in standing water, and problems with shaft linings.
Underground construction methods
862270
862267
Influence of freezing on strata behaviour (In German English)
Completion
of freeze shaft Voerde (In German
and English)
Bittner. F Gluckauf V121. N19, 10 Ott 1985, P1423-1428 (german), P426-428 (english) (paper to the Shczfi Sinking and Tunnelling Colloquium, Berlin, 21-22 Feb 1985)
The sinking of the 630m Voerde shaft at the Walsum Colliery, Germany, is described. Extensive monitoring of research holes and the shaft showed horizontal displacements of several centimetres towards the shaft. Comparison with movements calculated at the planning stage suggests that, with careful prior examination, reliable convergence prediction is possible. Laboratory and field measurements on the frozen ground provided information invaluable in deciding on the wall and lining dimensions. Because of high loading by water and strata pressures, a new design of foundation evolved, which both
and
Stoss, K; Oellers, T Gluckauf VIZI. N19, 10 Ott 1985, P1438-1444 (german), P434-438 (english) (paper to the Shaft Sinking and Tunnelling Colloquium. Berlin. 21-22 Feb 1985)
Volume change on ground freezing can be positive or negative, being a function of material type, pore volume, permeability, saturation and freezing point. Volume change is examined for sand. clay and solid rock. The behaviour of frozen strata when shaft sinking in non-competent. waterbearing strata is largely viscous, and may manifest itself as wall movement, floor heave, fissuration or bed separation. The particular conditions under which these may occur are considered and pmCtiCd advice is given on how to minimise these deleterious effects, by proper design, planning and laboratory testing of core samples.
cj 1986 Pergamon Press Ltd. Reproduction
not permitted
Hill. J L; Bauer. E R in: Rock Mechanics in Productivity
and Protection (Proceedings of the Twenty-Fyth Symposium on Rock Mechanics, Evanston, Illinois, 25-27 June 1984) P603-614. Pub1 New York: AIME, 1984
Massive roof failures caused by the propagation of ‘cutter’ fractures, nearly vertical cracks which break to a height above the anchor horizon or along weak bedding planes, are common in the North Appalachian Coal Basin. Research shows correlation between cutter failure and elastic dykes. Analysis of rock pressure monitoring shows the roof acts as two cantilever beams when severed by a elastic dyke. Additional roof support supplies effective reinforcement against cutter failure, but only if installed shortly after mining.
General underground storage See:862075 Radioactive waste disposal See also: 862027, 862097 862265 Study of the compaction properties of potential clay-sand buffer mixtures for use in nuclear waste disposal
participated in water-sealing and avoided ;I clamping /one The steel lining design was chosen on grounds of cconomy.ease of installation and ability to withstand grater prrssure and shaft irregularity. The completion of this shaft demonstrates the feasibility of this sinking techmquc to 011s depth. and information gathered should simplify the planning and dimensioning of future shafts. 862268 Causes of fractured freeze pipes in the Hunxe shaft and their restoration (In German and English)
Wollers, K Gluckauf VIII, N19, IO Ott 1985. P1428-1433 (gerrnan~. P429-431 (english) (paper to the Shqft Sinking ant/ Tunnelling Colloquium, Berlin, 21-22 Feb 1985)
Part of the Hunxe shaft in Germany was sunk using the ground freezing technique. When sinking through mottled sandstone at a depth of 120m. concentric cleats formed around the shaft bottom and the shaft wall bulged out and started to crack, causing freeze pipe socket joints to leak. The cause was identified as incorrect geotechnical classification of Ems Greensand as a clay marl, whereas in fact it behaved as a stiff clay. leading to high annular stress and above average wall displacements. It is emphasised that seemingly ‘harmless’ geological formations should be suitably investigated before shaft sinking. Based on information gathered during this project, suggestions are made in order to reduce costs. These concern dimensioning of the ice wall. shaft lining and radius and site specific variables.
Dixon, DA: Gray, M N; Thomas, A W
862269
Engng Geol V21. N3/4, June 1985, P247-255
Shaft sinking in waterbearing (In German and English)
Results of tests of the compaction properties of clay-sand mixtures are presented. Both swelling and non-swelling clay materials were examined. A mixture of 50% sand and 50% clay by mass appears to optimise the physical properties of the buffer. The implications of the results to the Canadian nuclear fuel waste management concept are discussed. 862266 Construction Gossow, V
of a large storage for critical
waste
Engng Geol V21, N3/4, June 1985, P349-358
Construction of a long-term storage for critical waste is described. The base impermeability layer consisted of natural clay. The method of placement and the permeability coefficients obtained are described.
non-competent
strata in China
Ma, Y: Wang. S Gluckauf VIZI. NIY, IO Ott 1985, P1434-1437 (germatt), P432-434 (english) (paper to the Shqft Sinking and TunneNing Colloquium, Berlin, 21-2-1Feb 1985 )
The most common methods of sinking shafts through waterbearing. non-competent strata in China are ground freezing and an improved drop shaft method - the mud drop shaft, with debris recovered from the standing water. Shaft boring or soil grouting are used rarely. Improvements to the freezing technique over 30 years are briefly reviewed.in particular the accuracy of freeze boreholes. the ice wall and optimisation of the freezing process. The construction and stress fields of shaft linings are discussed. For the drop shaft, work has concentrated on excavation in standing water, and problems with shaft linings.
Underground construction methods
862270
862267
Influence of freezing on strata behaviour (In German English)
Completion
of freeze shaft Voerde (In German
and English)
Bittner. F Gluckauf V121. N19, 10 Ott 1985, P1423-1428 (german), P426-428 (english) (paper to the Shczfi Sinking and Tunnelling Colloquium, Berlin, 21-22 Feb 1985)
The sinking of the 630m Voerde shaft at the Walsum Colliery, Germany, is described. Extensive monitoring of research holes and the shaft showed horizontal displacements of several centimetres towards the shaft. Comparison with movements calculated at the planning stage suggests that, with careful prior examination, reliable convergence prediction is possible. Laboratory and field measurements on the frozen ground provided information invaluable in deciding on the wall and lining dimensions. Because of high loading by water and strata pressures, a new design of foundation evolved, which both
and
Stoss, K; Oellers, T Gluckauf VIZI. N19, 10 Ott 1985, P1438-1444 (german), P434-438 (english) (paper to the Shaft Sinking and Tunnelling Colloquium. Berlin. 21-22 Feb 1985)
Volume change on ground freezing can be positive or negative, being a function of material type, pore volume, permeability, saturation and freezing point. Volume change is examined for sand. clay and solid rock. The behaviour of frozen strata when shaft sinking in non-competent. waterbearing strata is largely viscous, and may manifest itself as wall movement, floor heave, fissuration or bed separation. The particular conditions under which these may occur are considered and pmCtiCd advice is given on how to minimise these deleterious effects, by proper design, planning and laboratory testing of core samples.
cj 1986 Pergamon Press Ltd. Reproduction
not permitted