Determination of time-dependent strengths of salt pillars based on strain energy principle
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摘要
The objective of this study is to determine the time-dependent strengths of salt mine pillars in the Maha Sarakham formation, northeast of Thailand. Strain rate-controlled triaxial compression tests have been performed on salt specimens under confining pressures from 0 MPa to 12 MPa. The strain rates are from 10~(-7) s~(-1) to 10~(-4) s~(-1). The axial stresses and lateral strains are monitored through the strain-softening region. The results indicate that the strengths and elastic moduli increase exponentially with the strain rates. The power creep law parameters are calibrated with the test results, and hence allows constructing series of strain-time curves for the salt pillars under different depths and extraction ratios. The strain energy density principle is applied to develop a strength criterion for the salt pillars. Combining this criterion with the series of the strain-time curves the time-dependent strengths of the salt pillars for different extraction ratios can be predicted.
The objective of this study is to determine the time-dependent strengths of salt mine pillars in the Maha Sarakham formation, northeast of Thailand. Strain rate-controlled triaxial compression tests have been performed on salt specimens under confining pressures from 0 MPa to 12 MPa. The strain rates are from 10~(-7) s~(-1) to 10~(-4) s~(-1). The axial stresses and lateral strains are monitored through the strain-softening region. The results indicate that the strengths and elastic moduli increase exponentially with the strain rates. The power creep law parameters are calibrated with the test results, and hence allows constructing series of strain-time curves for the salt pillars under different depths and extraction ratios. The strain energy density principle is applied to develop a strength criterion for the salt pillars. Combining this criterion with the series of the strain-time curves the time-dependent strengths of the salt pillars for different extraction ratios can be predicted.
The objective of this study is to determine the time-dependent strengths of salt mine pillars in the Maha Sarakham formation, northeast of Thailand. Strain rate-controlled triaxial compression tests have been performed on salt specimens under confining pressures from 0 MPa to 12 MPa. The strain rates are from 10~(-7) s~(-1) to 10~(-4) s~(-1). The axial stresses and lateral strains are monitored through the strain-softening region. The results indicate that the strengths and elastic moduli increase exponentially with the strain rates. The power creep law parameters are calibrated with the test results, and hence allows constructing series of strain-time curves for the salt pillars under different depths and extraction ratios. The strain energy density principle is applied to develop a strength criterion for the salt pillars. Combining this criterion with the series of the strain-time curves the time-dependent strengths of the salt pillars for different extraction ratios can be predicted.
引文
[1]American Society for Testing and Materials.Standard test methods for creep of rock core under constant stress and temperature(ASTM D7070-08),Annual Book of ASTM Standards.West Conshohocken:American Society for Testing and Materials;2008.
[2]American Society for Testing and Materials.Compressive Strength and Elastic Moduli of Intact Rock Core Specimens under Varying States of Stress and Temperatures(ASTM D7012-07),Annual Book of ASTM Standards.West Conshohocken:American Society for Testing and Materials;2007.
[3]Liang WG,Zhao YS,Xu SG,Dusseault MB.Effect of strain rate on the mechanical properties of salt rock.Int J Rock Mech Min Sci 2010;48:161-7.
[4]Fuenkajorn K,Daemen JJK.Borehole closure in salt.Washington DC:Technical Report Prepared for the U.S.Nuclear Regulatory Commission;1988.
[5]Fuenkajorn K,Sriapai T,Samsri P.Effects of loading rate on strength and deformability of Maha Sarakham salt.Eng Geol 2012;135-136:10-23.
[6]Warren J.Evaporites:their evolution and economics.Oxford:Blackwell Science;1999.
[7]Fuenkajorn K,Daemen JJK.Boreholes closure in salt.University of Arizona:Technical Report Prepared for The U.S.Nuclear Regulatory Commission;1988.
[8]Lajtai EZ,Duncan EJS,Carter BJ.The effect of strain rate on rock strength.Rock Mech Rock Eng 1991;24:99-109.
[9]Liang WG,Zhao YS,Xu SG,Dusseault MB.Effect of strain rate on the mechanical properties of salt rock.Int J Rock Mech Min Sci 2011;48:161-7.
[10]Jaeger JC,Cook NGW,Zimmerman RW.Fundamentals of rock mechanics.4th ed.Oxford:Blackwell Science;2007.
[11]Luangthip A,Khamrat S,Fuenkajorn K.Effects of carnallite contents on stability and extraction ratio of potash Mine.In:Proceedings of 9th Asian Rock Mechanics Symposium.Bali,Indonesia:Indonesian Rock Mechanics Society;2016.
[12]Senseny PE.Review of constitutive laws used to describe the creep of salt.Columbus:Battelle Memorial Institute;1983.
[13]Nair RS,Chang CY,Singh RD,Abdullah AM.Time-dependent analysis to predict closure in salt cavities.In:Proceedings of the 4th Symposium on Salt.Cleveland,Ohio:Northern Ohio Geological Society;1974.
[14]Nair K,Boresi AP.Stress analysis for time-dependent problems in rock mechanics.In:Proceedings of the 2nd Congress of the International Society for Rock Mechanics.Belgrade:Institute for Development of Water Resources;1970.
[15]Wendai L.Regression analysis,linear regression and probit regression in 13chapters,SPSS for Windows:statistical analysis.Beijing:Publishing House of Electronics;2000.
[16]Hoek E,Brown ET.Empirical strength criterion for rock masses.J Geotech Eng Div 1980;160(GT9):1013-35.
[17]Kortnik J.Optimization of the high safety pillars for the underground excavation of natural stone blocks.Acta Geotech Slov 2009;1.
[18]Reed G,Mctyer K,Frith R.An assessment of coal pillar system stability criteria based on a mechanistic evaluation of the interaction between coal pillars and the overburden.Int J Min Sci Technol 2017;27(1):9-15.
[19]Sainoki A,Mitri HS.Numerical investigation into pillar failure induced by time-dependent skin degradation.Int J Min Sci Technol 2017;27(4):591-7.
[20]Deliveris AV,Benardos A.Evaluating performance of lignite pillars with 2Dapproximation techniques and 3D numerical analyses.Int J Min Sci Technol2017;27(6):929-36.
[21]Deb D,Verma AK.Fundamentals and Applications of Rock Mechanics.New Delhi:PHI Learning Private Limited;2016.
[2]American Society for Testing and Materials.Compressive Strength and Elastic Moduli of Intact Rock Core Specimens under Varying States of Stress and Temperatures(ASTM D7012-07),Annual Book of ASTM Standards.West Conshohocken:American Society for Testing and Materials;2007.
[3]Liang WG,Zhao YS,Xu SG,Dusseault MB.Effect of strain rate on the mechanical properties of salt rock.Int J Rock Mech Min Sci 2010;48:161-7.
[4]Fuenkajorn K,Daemen JJK.Borehole closure in salt.Washington DC:Technical Report Prepared for the U.S.Nuclear Regulatory Commission;1988.
[5]Fuenkajorn K,Sriapai T,Samsri P.Effects of loading rate on strength and deformability of Maha Sarakham salt.Eng Geol 2012;135-136:10-23.
[6]Warren J.Evaporites:their evolution and economics.Oxford:Blackwell Science;1999.
[7]Fuenkajorn K,Daemen JJK.Boreholes closure in salt.University of Arizona:Technical Report Prepared for The U.S.Nuclear Regulatory Commission;1988.
[8]Lajtai EZ,Duncan EJS,Carter BJ.The effect of strain rate on rock strength.Rock Mech Rock Eng 1991;24:99-109.
[9]Liang WG,Zhao YS,Xu SG,Dusseault MB.Effect of strain rate on the mechanical properties of salt rock.Int J Rock Mech Min Sci 2011;48:161-7.
[10]Jaeger JC,Cook NGW,Zimmerman RW.Fundamentals of rock mechanics.4th ed.Oxford:Blackwell Science;2007.
[11]Luangthip A,Khamrat S,Fuenkajorn K.Effects of carnallite contents on stability and extraction ratio of potash Mine.In:Proceedings of 9th Asian Rock Mechanics Symposium.Bali,Indonesia:Indonesian Rock Mechanics Society;2016.
[12]Senseny PE.Review of constitutive laws used to describe the creep of salt.Columbus:Battelle Memorial Institute;1983.
[13]Nair RS,Chang CY,Singh RD,Abdullah AM.Time-dependent analysis to predict closure in salt cavities.In:Proceedings of the 4th Symposium on Salt.Cleveland,Ohio:Northern Ohio Geological Society;1974.
[14]Nair K,Boresi AP.Stress analysis for time-dependent problems in rock mechanics.In:Proceedings of the 2nd Congress of the International Society for Rock Mechanics.Belgrade:Institute for Development of Water Resources;1970.
[15]Wendai L.Regression analysis,linear regression and probit regression in 13chapters,SPSS for Windows:statistical analysis.Beijing:Publishing House of Electronics;2000.
[16]Hoek E,Brown ET.Empirical strength criterion for rock masses.J Geotech Eng Div 1980;160(GT9):1013-35.
[17]Kortnik J.Optimization of the high safety pillars for the underground excavation of natural stone blocks.Acta Geotech Slov 2009;1.
[18]Reed G,Mctyer K,Frith R.An assessment of coal pillar system stability criteria based on a mechanistic evaluation of the interaction between coal pillars and the overburden.Int J Min Sci Technol 2017;27(1):9-15.
[19]Sainoki A,Mitri HS.Numerical investigation into pillar failure induced by time-dependent skin degradation.Int J Min Sci Technol 2017;27(4):591-7.
[20]Deliveris AV,Benardos A.Evaluating performance of lignite pillars with 2Dapproximation techniques and 3D numerical analyses.Int J Min Sci Technol2017;27(6):929-36.
[21]Deb D,Verma AK.Fundamentals and Applications of Rock Mechanics.New Delhi:PHI Learning Private Limited;2016.