Effects of Thermal Treatment on the Dynamic Mechanical Properties of Coal Measures Sandstone

Many projects such as the underground gasification of coal seams and coal-bed methane mining (exploitation) widely involve the dynamic problems of coal measures sandstone achieved via thermal treatment. This study examines the dynamic mechanical properties of coal measures sandstone after thermal treatment by means of an MTS653 high-temperature furnace and Split Hopkinson pressure bar test system. Experimental results indicate that 500 °C is a transition point for the dynamic mechanical parameters of coal measures sandstone. The dynamic elastic modulus and peak strength increase linearly from 25 to 500 °C while the dynamic peak strain decreases linearly over the same temperature range. The dynamic elastic modulus and peak strength drop quickly from 500 to 800 °C, with a significant increase in the dynamic peak strain over the same temperature range. The rock mechanics are closely linked to material composition and mesoscopic structure. Analysis by X-ray diffraction and scanning electron microscopy indicate that the molecules inside the sandstone increase in density due to the thermal expansion of the material particles, which effectively improves the deformation resistance and carrying capacity of the sandstone and reduces the likelihood of axial deformation. With heat treatment that exceeds 500 °C, the dynamic mechanical properties rapidly weaken due to the decomposition of kaolinite; additionally, hot cracking of the mineral particles within the materials arises from coal sandstone internal porosity, and other defects gradually appear.

[1]  Frédéric Skoczylas,et al.  Effects of heating on the hydraulic and poroelastic properties of bourgogne limestone , 2005 .

[2]  Heping Xie,et al.  Mechanical characteristics and microcosmic mechanisms of granite under temperature loads , 2008 .

[3]  Rosanna Smith,et al.  The influence of thermal and cyclic stressing on the strength of rocks from Mount St. Helens, Washington , 2013, Bulletin of Volcanology.

[4]  Jia Ming,et al.  Effects of heat treatment temperature on crystallization and thermal expansion coefficient of Li2O-Al2O3-SiO2 , 2004 .

[5]  Shanyong Wang,et al.  A coupled thermo-hydrologic-mechanical damage model and associated application in a stability analysis on a rock pillar , 2013 .

[6]  Qingyuan Wang,et al.  Online SEM investigation of microcrack characteristics of concretes at various temperatures , 2005 .

[7]  F. Heuze,et al.  High-temperature mechanical, physical and Thermal properties of granitic rocks— A review , 1983 .

[8]  T. Reuschlé,et al.  Acoustic wave velocity and permeability evolution during pressure cycles on a thermally cracked granite , 2000 .

[9]  M. J. Forrestal,et al.  A split Hopkinson pressure bar technique to determine compressive stress-strain data for rock materials , 2001 .

[10]  B. Mohanty,et al.  Effects of microstructures on dynamic compression of Barre granite , 2008 .

[11]  G. Grasselli,et al.  Fracture Toughness and Fracture Roughness Interrelationship in Thermally treated Westerly Granite , 2009 .

[12]  Xibing Li,et al.  Numerical simulation on rock failure under combined static and dynamic loading during SHPB tests , 2012 .

[13]  Jean Sulem,et al.  Stress dependent thermal pressurization of a fluid-saturated rock , 2008, 0808.3886.

[14]  K. T. Ramesh,et al.  High Rates and Impact Experiments , 2008 .

[15]  X. Mao,et al.  The Mechanical Properties of Mudstone at High Temperatures: an Experimental Study , 2014, Rock Mechanics and Rock Engineering.

[16]  W. Sharpe.  Springer Handbook of Experimental Solid Mechanics , 2008 .

[17]  S. H. Perry,et al.  Compressive behaviour of concrete at high strain rates , 1991 .

[18]  Hongyuan Liu,et al.  A Mesostructure-based Damage Model for Thermal Cracking Analysis and Application in Granite at Elevated Temperatures , 2015, Rock Mechanics and Rock Engineering.

[19]  Xibing Li,et al.  Dynamic Characteristics of Granite Subjected to Intermediate Loading Rate , 2005 .

[20]  M. Doan,et al.  High strain rate damage of Carrara marble , 2011 .

[21]  S. J. Green,et al.  Uniaxial stress behavior of porphyritic tonalite at strain rates to 103/second , 1970 .

[22]  Youqing Chen,et al.  Influence of thermal damage on linear and nonlinear acoustic properties of granite , 2013 .

[23]  Application of isothermal calorimetry and thermal analysis for the investigation of calcined gypsum–lime–metakaolin–water system , 2015, Journal of Thermal Analysis and Calorimetry.

[24]  Liang Wang,et al.  High-Temperature Mechanical Properties of Mudstone in the Process of Underground Coal Gasification , 2011 .

[25]  T. Reuschlé,et al.  The effect of heating on the microstructural evolution of La Peyratte granite deduced from acoustic velocity measurements , 2006 .

[26]  F. Yuan,et al.  Origin of pulverized rocks during earthquake fault rupture , 2011 .

[27]  S. Chaki,et al.  Influence of thermal damage on physical properties of a granite rock: Porosity, permeability and ultrasonic wave evolutions , 2008 .

[28]  Yinlong Lu,et al.  Thermophysical properties of coal measure strata under high temperature , 2015, Environmental Earth Sciences.

[29]  Qianbing Zhang,et al.  Determination of mechanical properties and full-field strain measurements of rock material under dynamic loads , 2013 .

[30]  S. Siegesmund,et al.  The bowing potential of granitic rocks: rock fabrics, thermal properties and residual strain , 2008 .

[31]  F. Homand-Etienne,et al.  Thermally induced microcracking in granites: characterization and analysis , 1989 .

[32]  Xibing Li,et al.  Effect of Thermal Treatment on the Dynamic Fracture Toughness of Laurentian Granite , 2012, Rock Mechanics and Rock Engineering.

[33]  Per-Arne Lindqvist,et al.  Effects of high temperatures on dynamic rock fracture , 2001 .

[34]  H. Kolsky.  An Investigation of the Mechanical Properties of Materials at very High Rates of Loading , 1949 .

[35]  Xin Han,et al.  The Simulation Analysis of Fire Feature on Underground Substation , 2012 .

[36]  Mark L. Green,et al.  Development of a dynamic triaxial Kolsky bar , 2010 .

[37]  E. Salje,et al.  Thermodynamics of sodium feldspar II: Experimental results and numerical calculations , 1985 .

[38]  Yuri Popov,et al.  Interrelations Between Thermal Conductivity and Other Physical Properties of Rocks: Experimental Data , 2003, Pure and Applied Geophysics.

[39]  Gray,et al.  Classic Split-Hopkinson Pressure Bar Testing , 2000 .

[40]  L. L. Ngueyep Mambou,et al.  Theoretical investigations of mechanical properties of sandstone rock specimen at high temperatures , 2014, Journal of Mining Science.

[41]  M. Darot,et al.  Influence of stress-induced and thermal cracking on physical properties and microstructure of La Peyratte granite , 1999 .

[42]  D. Viete,et al.  Transformation plasticity and the effect of temperature on the mechanical behaviour of Hawkesbury sandstone at atmospheric pressure , 2012 .

[43]  Paola Marini,et al.  Experimental Studies on the Mechanical Behaviour of two Thermal Cracked Marbles , 2001 .

[44]  S. Dech,et al.  Thermal Infrared Remote Sensing of Surface and Underground Coal Fires , 2013 .

[45]  P. Meredith,et al.  Acoustic emission and fluid permeability measurements on thermally cracked rocks , 1997 .

[46]  Jian Zhao,et al.  A Review of Dynamic Experimental Techniques and Mechanical Behaviour of Rock Materials , 2014, Rock Mechanics and Rock Engineering.

[47]  Shi Liu,et al.  Staged Moduli: A Quantitative Method to Analyze the Complete Compressive Stress–Strain Response for Thermally Damaged Rock , 2015, Rock Mechanics and Rock Engineering.

[48]  H. Yavuz,et al.  Thermal effect on the physical properties of carbonate rocks , 2010 .

[49]  John A. Hudson,et al.  Draft ISRM suggested method for the complete stress-strain curve for intact rock in uniaxial compression , 1999 .

[50]  John M Kemeny,et al.  Effect of Rapid Thermal Cooling on Mechanical Rock Properties , 2013, Rock Mechanics and Rock Engineering.

[51]  Jonathan Procter,et al.  Ana Maria Malheiro and João Carlos Nunes (eds): Volcanic rocks—proceedings of ISRM Workshop W2, Ponta Delgada, Azores, Portugal, 14–15 July, 2007 , 2013, Bulletin of Volcanology.

[52]  Ezio Cadoni,et al.  Dynamic Characterization of Orthogneiss Rock Subjected to Intermediate and High Strain Rates in Tension , 2010 .

[53]  Heping Xie,et al.  Thermal-mechanical coupled effect on fracture mechanism and plastic characteristics of sandstone , 2007 .

[54]  M. Doan,et al.  Rock pulverization at high strain rate near the San Andreas Fault , 2009 .

[55]  N. Sengun.  Influence of thermal damage on the physical and mechanical properties of carbonate rocks , 2014, Arabian Journal of Geosciences.

[56]  Xibing Li,et al.  Effects of Thermal Treatment on Tensile Strength of Laurentian Granite Using Brazilian Test , 2015, Rock Mechanics and Rock Engineering.

[57]  Aihong Lu,et al.  Experimental study on the mechanical properties of rocks at high temperature , 2009 .

[58]  S. P. Pradhan,et al.  Tensile Strength of Rock Under Elevated Temperatures , 2011 .

[59]  Nengxiong Xu,et al.  Physical Properties of Sandstones After High Temperature Treatment , 2012, Rock Mechanics and Rock Engineering.

[60]  Jian Zhao,et al.  Effect of loading rate on fracture toughness and failure micromechanisms in marble , 2013 .

[61]  Peter K. Kaiser,et al.  A study on the dynamic behavior of the Meuse/Haute-Marne argillite , 2007 .

[62]  Y. Mahmutoğlu.  Mechanical Behaviour of Cyclically Heated Fine Grained Rock , 1998 .

[63]  A. Chakraborty.  Phase Transformation of Kaolinite Clay , 2013 .

[64]  K. T. Ramesh,et al.  The dynamic strength of an ordinary chondrite , 2011 .

[65]  Gérard Gary,et al.  Evaluation of stress–strain curve estimates in dynamic experiments , 2010 .