An abrasive water jet(AWJ)is commonly used to develop deep geothermal resources,such as drilling in hot dry rock(HDR).The influence of rock mineral properties,such as mineral types,mineral contents,and grain size,on t...An abrasive water jet(AWJ)is commonly used to develop deep geothermal resources,such as drilling in hot dry rock(HDR).The influence of rock mineral properties,such as mineral types,mineral contents,and grain size,on the formation of perforation by AWJ is unclear yet.In this study,we investigate AWJ impacts on three types of granite samples with different mineral fractions using a polarizing microscope and scanning electron microscope(SEM).The results show that when the grain size is doubled,the perforation depth increases by 16.22%under the same type of structure and properties.In general,fractures are more likely to be created at the position of rough surfaces caused by abrasive impact,and the form of fractures is determined by the mineral type.In addition,microstructure analysis shows that transgranular fractures typically pass through large feldspar particles and quartz removal occurs along mineral boundaries.The longitudinal extension of perforation depends mainly on the strong kinetic energy of the jet,while the lateral extension is controlled by the backflow.The results contribute to a better understanding of the process involved in the breaking of hard rock by abrasive jets during deep geothermal drilling.展开更多
In the application of high-pressure water jet assisted breaking of deep underground rock engineering,the influence mechanism of rock temperature on the rock fragmentation process under jet action is still unclear.Ther...In the application of high-pressure water jet assisted breaking of deep underground rock engineering,the influence mechanism of rock temperature on the rock fragmentation process under jet action is still unclear.Therefore,the fluid evolution characteristics and rock fracture behavior during jet impingement were studied.The results indicate that the breaking process of high-temperature rock by jet impact can be divided into four stages:initial fluid-solid contact stage,intense thermal exchange stage,perforation and fracturing stage,and crack propagation and penetration stage.With the increase of rock temperature,the jet reflection angles and the time required for complete cooling of the impact surface significantly decrease,while the number of cracks and crack propagation rate significantly increase,and the rock breaking critical time is shortened by up to 34.5%.Based on numerical simulation results,it was found that the center temperature of granite at 400℃ rapidly decreased from 390 to 260℃ within 0.7 s under jet impact.In addition,a critical temperature and critical heat flux prediction model considering the staged breaking of hot rocks was established.These findings provide valuable insights to guide the water jet technology assisted deep ground hot rock excavation project.展开更多
In subsurface projects where the host rock is of low permeability,fractures play an important role in fluid circulation.Both the geometrical and mechanical properties of the fracture are relevant to the permeability o...In subsurface projects where the host rock is of low permeability,fractures play an important role in fluid circulation.Both the geometrical and mechanical properties of the fracture are relevant to the permeability of the fracture.To evaluate this relationship,we numerically generated self-affine fractures reproducing the scaling relationship of the power spectral density(PSD)of the measured fracture surfaces.The fractures were then subjected to a uniform and stepwise increase in normal stress.A fast Fourier transform(FFT)-based elastic contact model was used to simulate the fracture closure.The evolution of fracture contact area,fracture closure,and fracture normal stiffness were determined throughout the whole process.In addition,the fracture permeability at each step was calculated by the local cubic law(LCL).The influences of roughness exponent and correlation length on the fracture hydraulic and mechanical behaviors were investigated.Based on the power law of normal stiffness versus normal stress,the corrected cubic law and the linear relationship between fracture closure and mechanical aperture were obtained from numerical modeling of a set of fractures.Then,we derived a fracture normal stiffness-permeability equation which incorporates fracture geometric parameters such as the root-mean-square(RMS),roughness exponent,and correlation length,which can describe the fracture flow under an effective medium regime and a percolation regime.Finally,we interpreted the flow transition behavior from the effective medium regime to the percolation regime during fracture closure with the established stiffness-permeability function.展开更多
A comprehensive understanding of shale’s bedding anisotropy is crucial for shale-related engineering activities,such as hydraulic fracturing,drilling and underground excavation.In this study,seven Brazilian tests wer...A comprehensive understanding of shale’s bedding anisotropy is crucial for shale-related engineering activities,such as hydraulic fracturing,drilling and underground excavation.In this study,seven Brazilian tests were conducted on shale samples at different bedding orientations with respect to the loading direction(0°,45°and 90°)and the disc end face(0°,45°and 90°).An acoustic emission(AE)system was employed to capture the evolution of damage and the temporal-spatial distribution of microcracks under splitting-tensile stress.The results show that the Brazilian tensile strength decreases with increasing bedding inclination with respect to the disc end face,while it increases with the angle between bedding and loading directions.Increasing the bedding inclination with respect to the end face facilitates the reduction in b value and enhances the shale’s resistance to microcrack growth during the loading process.Misalignment between the bedding orientation and the end face suppresses the growth of mixed tensile-shear microcracks,while reducing the bedding angle relative to the loading direction is beneficial for creating mixed tensile-shear and tensile cracks.The observed microscopic failure characteristics are attributed to the competing effects of bedding activation and breakage of shale matrix at different bedding inclinations.The temporal-spatial distribution of microcracks,characterized by AE statistics including the correlation dimension and spatial correlation length,illustrates that the fractal evolution of microcracks is independent of bedding anisotropy,whereas the spatial distribution shows a stronger correlation.The evolution features of correlation dimension and spatial correlation length could be potentially used as precursors for shale splitting failure.These findings may be useful for predicting rock mass instability and analyzing the causes of catastrophic rupture.展开更多
At present,Hepatocarcinoma is one of the main causes of tumor related death all over the world.However,there are still many clinical restrictions on the treatment of liver cancer.Recently,L-Selenocystine has been show...At present,Hepatocarcinoma is one of the main causes of tumor related death all over the world.However,there are still many clinical restrictions on the treatment of liver cancer.Recently,L-Selenocystine has been shown to be a novel treatment for tumors,especially human glioma cells.But,the mechanism of L-Selenocystine against hepatocellular carcinoma remains unclear.Therefore,the main objective of this study was to investigate the effects of L-Selenocystine on HepG2 cell proliferation and activation of reactive oxygen species(ROS)mediated signaling pathway.L-Selenocystine can significantly inhibit HepG2 cell proliferation by activating caspase-3 and cleaving PARP to induce apoptosis.Moreover,the excessive production of ROS and the influence of Bax signaling pathway which can promote cell apoptosis are key factors for L-Selenocystine to induce HepG2 cell apoptosis.Therefore,the date of this study suggest that ROS mediated signal transduction mechanism may provide certain reference significance for L-Selenocystine induced HepG2 cell apoptosis.展开更多
基金supported by the Postdoctoral Fellowship Program of CPSF(Grant No.GZC20233326)the Chongqing Science Fund for Distinguished Young Scholars(Grant No.CSTB2022NSCQJQX0028)the National Natural Science Foundation of China(Grant Nos.U23A20597,52274112).
文摘An abrasive water jet(AWJ)is commonly used to develop deep geothermal resources,such as drilling in hot dry rock(HDR).The influence of rock mineral properties,such as mineral types,mineral contents,and grain size,on the formation of perforation by AWJ is unclear yet.In this study,we investigate AWJ impacts on three types of granite samples with different mineral fractions using a polarizing microscope and scanning electron microscope(SEM).The results show that when the grain size is doubled,the perforation depth increases by 16.22%under the same type of structure and properties.In general,fractures are more likely to be created at the position of rough surfaces caused by abrasive impact,and the form of fractures is determined by the mineral type.In addition,microstructure analysis shows that transgranular fractures typically pass through large feldspar particles and quartz removal occurs along mineral boundaries.The longitudinal extension of perforation depends mainly on the strong kinetic energy of the jet,while the lateral extension is controlled by the backflow.The results contribute to a better understanding of the process involved in the breaking of hard rock by abrasive jets during deep geothermal drilling.
基金supported by National Natural Science Foundation of China (No.U23A20597)National Major Science and Technology Project of China (No.2024ZD1003803)+1 种基金Chongqing Science Fund for Distinguished Young Scholars of Chongqing Municipality (No.CSTB2022NSCQ-JQX0028)Natural Science Foundation of Chongqing (No.CSTB2024NSCQ-MSX0503)。
文摘In the application of high-pressure water jet assisted breaking of deep underground rock engineering,the influence mechanism of rock temperature on the rock fragmentation process under jet action is still unclear.Therefore,the fluid evolution characteristics and rock fracture behavior during jet impingement were studied.The results indicate that the breaking process of high-temperature rock by jet impact can be divided into four stages:initial fluid-solid contact stage,intense thermal exchange stage,perforation and fracturing stage,and crack propagation and penetration stage.With the increase of rock temperature,the jet reflection angles and the time required for complete cooling of the impact surface significantly decrease,while the number of cracks and crack propagation rate significantly increase,and the rock breaking critical time is shortened by up to 34.5%.Based on numerical simulation results,it was found that the center temperature of granite at 400℃ rapidly decreased from 390 to 260℃ within 0.7 s under jet impact.In addition,a critical temperature and critical heat flux prediction model considering the staged breaking of hot rocks was established.These findings provide valuable insights to guide the water jet technology assisted deep ground hot rock excavation project.
基金supported by the China Postdoctoral Science Foundation Funded Project(Grant No.2023M740385)the Postdoctoral Fellowship Program of CPSF(Grant No.GZC20233326)the support by the Helmholtz Association's Initiative and Networking Fund for the Helmholtz Young Investigator Group ARES(Contract No.VH-NG-1516).
文摘In subsurface projects where the host rock is of low permeability,fractures play an important role in fluid circulation.Both the geometrical and mechanical properties of the fracture are relevant to the permeability of the fracture.To evaluate this relationship,we numerically generated self-affine fractures reproducing the scaling relationship of the power spectral density(PSD)of the measured fracture surfaces.The fractures were then subjected to a uniform and stepwise increase in normal stress.A fast Fourier transform(FFT)-based elastic contact model was used to simulate the fracture closure.The evolution of fracture contact area,fracture closure,and fracture normal stiffness were determined throughout the whole process.In addition,the fracture permeability at each step was calculated by the local cubic law(LCL).The influences of roughness exponent and correlation length on the fracture hydraulic and mechanical behaviors were investigated.Based on the power law of normal stiffness versus normal stress,the corrected cubic law and the linear relationship between fracture closure and mechanical aperture were obtained from numerical modeling of a set of fractures.Then,we derived a fracture normal stiffness-permeability equation which incorporates fracture geometric parameters such as the root-mean-square(RMS),roughness exponent,and correlation length,which can describe the fracture flow under an effective medium regime and a percolation regime.Finally,we interpreted the flow transition behavior from the effective medium regime to the percolation regime during fracture closure with the established stiffness-permeability function.
基金supported by the National Natural Science Foundation of China (Grant No.52364004)the Basic Research Project of Guizhou University (Grant No.[2023]40)support by the Helmholtz Association’s Initiative and Networking Fund for the Helmholtz Young Investigator Group ARES (Contract No.VH-NG-1516).
文摘A comprehensive understanding of shale’s bedding anisotropy is crucial for shale-related engineering activities,such as hydraulic fracturing,drilling and underground excavation.In this study,seven Brazilian tests were conducted on shale samples at different bedding orientations with respect to the loading direction(0°,45°and 90°)and the disc end face(0°,45°and 90°).An acoustic emission(AE)system was employed to capture the evolution of damage and the temporal-spatial distribution of microcracks under splitting-tensile stress.The results show that the Brazilian tensile strength decreases with increasing bedding inclination with respect to the disc end face,while it increases with the angle between bedding and loading directions.Increasing the bedding inclination with respect to the end face facilitates the reduction in b value and enhances the shale’s resistance to microcrack growth during the loading process.Misalignment between the bedding orientation and the end face suppresses the growth of mixed tensile-shear microcracks,while reducing the bedding angle relative to the loading direction is beneficial for creating mixed tensile-shear and tensile cracks.The observed microscopic failure characteristics are attributed to the competing effects of bedding activation and breakage of shale matrix at different bedding inclinations.The temporal-spatial distribution of microcracks,characterized by AE statistics including the correlation dimension and spatial correlation length,illustrates that the fractal evolution of microcracks is independent of bedding anisotropy,whereas the spatial distribution shows a stronger correlation.The evolution features of correlation dimension and spatial correlation length could be potentially used as precursors for shale splitting failure.These findings may be useful for predicting rock mass instability and analyzing the causes of catastrophic rupture.
基金This work was supported by the fund from Open Project of Guangdong Key Laboratory of Marine Materia Medica(LMM2020-7)the fund from Guangzhou Institute of Pediatrics/Guangzhou Women and Children’s Medical Center(Nos.Pre-NSFC-2019-016,YIP-2019-059,IP-2019-019)+3 种基金the Project of Traditional Chinese Medicine Bureau of Guangdong Province(No.20192075)the technology planning projects of Guangdong province(No.202102010202)The Guangdong Natural Science Foundation(2020A1515110648)the Open Fund of Guangdong Provincial Key Laboratory of Functional Supramolecular Coordination Materials and Applications(2020A03).
文摘At present,Hepatocarcinoma is one of the main causes of tumor related death all over the world.However,there are still many clinical restrictions on the treatment of liver cancer.Recently,L-Selenocystine has been shown to be a novel treatment for tumors,especially human glioma cells.But,the mechanism of L-Selenocystine against hepatocellular carcinoma remains unclear.Therefore,the main objective of this study was to investigate the effects of L-Selenocystine on HepG2 cell proliferation and activation of reactive oxygen species(ROS)mediated signaling pathway.L-Selenocystine can significantly inhibit HepG2 cell proliferation by activating caspase-3 and cleaving PARP to induce apoptosis.Moreover,the excessive production of ROS and the influence of Bax signaling pathway which can promote cell apoptosis are key factors for L-Selenocystine to induce HepG2 cell apoptosis.Therefore,the date of this study suggest that ROS mediated signal transduction mechanism may provide certain reference significance for L-Selenocystine induced HepG2 cell apoptosis.
