Understanding the thermo-mechanical behavior of various rock types is important in a wide range of geoscientific applications.In this study,the effects of elevated temperature treatments(250℃-750℃)on the elastic res...Understanding the thermo-mechanical behavior of various rock types is important in a wide range of geoscientific applications.In this study,the effects of elevated temperature treatments(250℃-750℃)on the elastic response(wave velocities and mechanical properties)of dolerite,retrieved from a borehole in the Sonhat Basin,India,were analyzed.The results showed that uniaxial compressive strength(UCS)increased by 15.4%at 250℃ compared to their room temperature(25℃)counterparts due to drying effects and inherent rock strengthening,but declined steadily at higher temperatures due to heat-induced microcracking and mineral transformations.Similarly,Young's modulus of the rock samples increased up to 250℃ and then decreased sharply above 450℃,aligning with the brittle-ductile transition temperature of 450℃.Petrographic and electron microscopy analyses of the samples revealed the development of intergranular and intragranular fractures at temperatures above 450℃,contributing to the observed mechanical weakening.Furthermore,ultrasonic wave velocities(P-and S-waves)exhibited significant reductions with increasing temperature,highlighting microstructural damage.These findings provide critical knowledge for designing underground geological engineering structures by identifying temperature thresholds and understanding mechanical degradation under thermal stress.The findings are particularly relevant for underground coal gasification(UCG)projects in the Sonhat Coalfield,where dolerite sills overlying coal seams may be exposed to significant heat.The identified threshold temperatures and trends in mechanical behaviour provide valuable insights for addressing structural stability challenges and mitigating environmental risks,such as surface subsidence.展开更多
基金funded by“The Pearl River Talent Recruitment Program”in 2019(Grant No.2019CX01G338)Guangdong Province and Guangdong Provincial Basic and Applied Basic Research Fund Committee(2022A1515240073).
文摘Understanding the thermo-mechanical behavior of various rock types is important in a wide range of geoscientific applications.In this study,the effects of elevated temperature treatments(250℃-750℃)on the elastic response(wave velocities and mechanical properties)of dolerite,retrieved from a borehole in the Sonhat Basin,India,were analyzed.The results showed that uniaxial compressive strength(UCS)increased by 15.4%at 250℃ compared to their room temperature(25℃)counterparts due to drying effects and inherent rock strengthening,but declined steadily at higher temperatures due to heat-induced microcracking and mineral transformations.Similarly,Young's modulus of the rock samples increased up to 250℃ and then decreased sharply above 450℃,aligning with the brittle-ductile transition temperature of 450℃.Petrographic and electron microscopy analyses of the samples revealed the development of intergranular and intragranular fractures at temperatures above 450℃,contributing to the observed mechanical weakening.Furthermore,ultrasonic wave velocities(P-and S-waves)exhibited significant reductions with increasing temperature,highlighting microstructural damage.These findings provide critical knowledge for designing underground geological engineering structures by identifying temperature thresholds and understanding mechanical degradation under thermal stress.The findings are particularly relevant for underground coal gasification(UCG)projects in the Sonhat Coalfield,where dolerite sills overlying coal seams may be exposed to significant heat.The identified threshold temperatures and trends in mechanical behaviour provide valuable insights for addressing structural stability challenges and mitigating environmental risks,such as surface subsidence.
