Thermal cracking is broadly observed in rock engineering.A finite element numerical model which considers the heterogeneity of rock materials and the damage evolution process was used to simulate the thermal cracking ...Thermal cracking is broadly observed in rock engineering.A finite element numerical model which considers the heterogeneity of rock materials and the damage evolution process was used to simulate the thermal cracking behavior of square rock samples heated from the central borehole.The thermal and mechanical behaviors of two cases,i.e.,the case with large size but low heating rate and the case with small size but high heating rate were compared to study the crack initiation location in the models with different model sizes and heating rates.The simulated stress and temperature fields,as well as the failure pattern,were in good agreement with the experimental observations.The temperature and thermal stress distribution during the heating process in both cases indicated that high tensile stress was concentrated around the thermal gradient front,which resulted in the cracks initiating at the location with a certain distance away from the borehole.The results show that under the same heating rate,crack initiation location moves outwards with the increment of the model size then remains approximately at one location,which reflects the boundary-effect.Furthermore,the results indicate that the relative crack initiation locations in two cases are nearly the same if the ratio between the heating rate in two cases(Tx/Ty)nearly equal to the square of the inverse ratio of corresponding model side lengths((ay/ax)2).This concept is named the scale-heating rate equivalence effect in this study.It is beneficial for studying thermal cracking of rock both numerically and experimentally since the model size can be significantly decreased.展开更多
With the results of interpretation of seismic sounding profiles acquired in the past 30 years in the continent of China and its adjacent countries and ocean regions, such as Russia, Ka-zakhstan, Japan, India, Pakistan...With the results of interpretation of seismic sounding profiles acquired in the past 30 years in the continent of China and its adjacent countries and ocean regions, such as Russia, Ka-zakhstan, Japan, India, Pakistan, Philippine ocean basin, Pacific and Indian Ocean, we compiled a 2D Moho distribution map for the continent and its adjacent areas of eastern Asia. From the fea-tures of depth distribution and undulation of Moho, it is suggested that the eastern Asian region can be divided into 18 gradient belts with different sizes, 18 crustal blocks, 20 sediment basins and depression zones. The depth of Moho varies smoothly in each block, while the boundary (separat-ing different blocks) delineates the abrupt variation of Moho depth. Then, some subjects,such as oregen and sediment basin, fault system and rift, plate boundary, ocean-continent coupling and tectonic framework, are discussed based on the distribution gradient belts and block partition fea-tures of Moho depth in the eastern Asia and its adjacent regions.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51874065)the National Major Scientific Instruments Development Project(Grant No.51627804).
文摘Thermal cracking is broadly observed in rock engineering.A finite element numerical model which considers the heterogeneity of rock materials and the damage evolution process was used to simulate the thermal cracking behavior of square rock samples heated from the central borehole.The thermal and mechanical behaviors of two cases,i.e.,the case with large size but low heating rate and the case with small size but high heating rate were compared to study the crack initiation location in the models with different model sizes and heating rates.The simulated stress and temperature fields,as well as the failure pattern,were in good agreement with the experimental observations.The temperature and thermal stress distribution during the heating process in both cases indicated that high tensile stress was concentrated around the thermal gradient front,which resulted in the cracks initiating at the location with a certain distance away from the borehole.The results show that under the same heating rate,crack initiation location moves outwards with the increment of the model size then remains approximately at one location,which reflects the boundary-effect.Furthermore,the results indicate that the relative crack initiation locations in two cases are nearly the same if the ratio between the heating rate in two cases(Tx/Ty)nearly equal to the square of the inverse ratio of corresponding model side lengths((ay/ax)2).This concept is named the scale-heating rate equivalence effect in this study.It is beneficial for studying thermal cracking of rock both numerically and experimentally since the model size can be significantly decreased.
基金supported by the National Natural Science Foundation of China (Grant No. 40074020) and the National Basic Science Research Project (Grant No. 95-S-05).
文摘With the results of interpretation of seismic sounding profiles acquired in the past 30 years in the continent of China and its adjacent countries and ocean regions, such as Russia, Ka-zakhstan, Japan, India, Pakistan, Philippine ocean basin, Pacific and Indian Ocean, we compiled a 2D Moho distribution map for the continent and its adjacent areas of eastern Asia. From the fea-tures of depth distribution and undulation of Moho, it is suggested that the eastern Asian region can be divided into 18 gradient belts with different sizes, 18 crustal blocks, 20 sediment basins and depression zones. The depth of Moho varies smoothly in each block, while the boundary (separat-ing different blocks) delineates the abrupt variation of Moho depth. Then, some subjects,such as oregen and sediment basin, fault system and rift, plate boundary, ocean-continent coupling and tectonic framework, are discussed based on the distribution gradient belts and block partition fea-tures of Moho depth in the eastern Asia and its adjacent regions.
