Understanding the anisotropic fracture behavior and the characteristics of the fracture process zone(FPZ)under size effects in laminated rocks,as well as its role in rock fracturing,is crucial for various engineering ...Understanding the anisotropic fracture behavior and the characteristics of the fracture process zone(FPZ)under size effects in laminated rocks,as well as its role in rock fracturing,is crucial for various engineering applications.In this study,three-point bending tests were conducted on shale specimens with varying bedding angles and sizes.The anisotropic characteristics and size effects of fracture parameters were revealed.A comparative analysis was performed on the evolutions of FPZs computed using size effect theory,digital image correlation(DIC),and linear elastic fracture mechanics.The results divulged that:(i)With increasing bedding angles,there is a noticeable decrease in apparent fracture toughness(KICA),apparent fracture energy(GICA),and nominal strength(σ_(Nu)).When the bedding angle of shale is less than 45°,the crack propagation and fracture parameters are mainly influenced by the matrix.Contrary,shale with bedding angles greater than 60°,the crack propagation and fracture parameters are mainly controlled by the bedding.When the bedding angle is between 45°and 60°,the fracture propagation evolves from permeating the matrix to extending along the bedding;(ii)The fracture parameters exhibit significant size dependent behavior,as KICA and GICA rise with increasing specimen size,butσNu falls with increasing specimen sizes.The fracture parameters align with the theoretical predictions of Bažant size effect law;and(iii)The lengths of DIC-based FPZ,effective FPZ,and inelastic zone follow W-shape variations with bedding angle.The dimensionless sizes of FPZ and inelastic zone decrease with specimen size,indicating a size effect.Furthermore,there is a negative relation between KICA and the dimensionless size of the FPZ,whileσNu is positively correlated to the dimensionless size of the FPZ.This highlights the essential role of the FPZ in the size effect of rock fracture.The bedding angle exerts an influence on the FPZ,subsequently affecting the anisotropic fracture and size-dependent behavior of shale.展开更多
This study investigates the fracture characteristics and the fracture process zone(FPZ)of mode I fracture in sandstone,aiming to analyze the propagation behaviors of mode I crack under different freeze-thaw cycles.Sem...This study investigates the fracture characteristics and the fracture process zone(FPZ)of mode I fracture in sandstone,aiming to analyze the propagation behaviors of mode I crack under different freeze-thaw cycles.Semicircular bending tests(SCB)were conducted using different freeze-thaw cycles to evaluate mode I fracture toughness,FPZ dynamics,and macroscopic microscopic features.Digital image correlation(DIC)and scanning electron microscopy(SEM)techniques were employed for detailed analysis.Experimental results reveal that freeze-thaw cycling leads to the widening of both preexisting and newly formed microcracks between internal particles.Under external loading,crack propagation deviates from prefabricated paths,forming serrated crack patterns.The FPZ initiates at the prefabricated crack tip and extends toward the loading end,exhibiting an arcshaped tip shape.The FPZ length increases with loading but decreases after reaching a peak value.With additional freeze-thaw cycles,the maximum FPZ length first increases and then diminishes.展开更多
An analytical expression for the prediction of shear-compressive fracture process zone(SCFPZ) is derived by using a proposed local strain energy density criterion, in which the strain energy density is separated into ...An analytical expression for the prediction of shear-compressive fracture process zone(SCFPZ) is derived by using a proposed local strain energy density criterion, in which the strain energy density is separated into the dilatational and distortional strain energy density, only the former is considered to contribute to the brittle fracture of rock in different loading cases. The theoretical prediction by this criterion shows that the SCFPZ is of asymmetric mulberry leaf in shape, which forms a shear-compression fracture kern. Dilatational strain energy density along the boundary of SCFPZ reaches its maximum value. The dimension of SCFPZ is governed by the ratio of K_Ⅱ to (K_Ⅰ.) The analytical results are then compared with those from literatures and the tests conducted on double edge cracked Brazilian disk subjected to diametrical compression. The obtained results are useful to the prediction of crack extension and to nonlinear analysis of shear-compressive fracture of brittle rock.展开更多
On the basis of that rock material usually has a larger fracture process zone,a new fracture criterion which is different from that of linear elastic fracture theory was presented.On this basis,the fracture behavior a...On the basis of that rock material usually has a larger fracture process zone,a new fracture criterion which is different from that of linear elastic fracture theory was presented.On this basis,the fracture behavior and influencing factors under modeⅡor compressive shear loading were investigated.展开更多
Two pollution zones in middle and lower reaches of Hanjiang River were selected for studying restoration processes. In each zones 6 stations were set up in upper stream of sewage outfall, 50m, 100 or 150m, 250 or 525m...Two pollution zones in middle and lower reaches of Hanjiang River were selected for studying restoration processes. In each zones 6 stations were set up in upper stream of sewage outfall, 50m, 100 or 150m, 250 or 525m and 1250 or 3500m apart from the outfall. Chemical monitoring and microbial community biomonitoring were carried out simultaneously. Either the chemical monitoring or the biological monitoring proved the self-purification process of water body along with the increased distance from the sewage outfall. 4 biological parameters (species number of protozoa, percentage of phytomastigophora, diversity index and heterotrophy index) and parameter Seq of the colonization process all have statistically significant correlations with chemical comprehensive pollution indexes Pa and Pb.展开更多
Three-dimensional thermal a nalysis simulation of a horizontal zone refining system is conducted for germanimn semiconductor materials. The considered geometry includes a g＇ral）hite boat filled with germanium placed...Three-dimensional thermal a nalysis simulation of a horizontal zone refining system is conducted for germanimn semiconductor materials. The considered geometry includes a g＇ral）hite boat filled with germanium placed in a cylindrical quartz tube. A flow of Ar and H2 gas mixture is purged througll the tube. A narrow section of the, boat is assmned to be exposed to a constant heat rate produced b v an rf coil located outside the quartz tube. The results of this analysis provide essential information about various parameters such as the shape of tile molten zone, required power and temperature gradient in the system.展开更多
At present, the international economy continues growing slowly, and the foreign trade situation is not optimistic. In addition, domestic demand are strongly encouraged and expanded in China. Compared with a prosperous...At present, the international economy continues growing slowly, and the foreign trade situation is not optimistic. In addition, domestic demand are strongly encouraged and expanded in China. Compared with a prosperous domestic market, enterprises in the export processing zone have few advantages. Domestic sales have become an inevitable trend. It is also beneficial for the transformation and upgrading of export processing zone. However, it is quite difficult to open up the domestic market for export-oriented enterprises in the area. They will encounter many obstacles. The government and enterprises should take appropriate measures to facilitate the enterprise to turn export to domestic sales.展开更多
In this paper we use theoretical analysis and extensive simulations to study zone inhomogeneity with the random asymmetric simple exclusion process （ASEP）. In the inhomogeneous zone, the hopping probability is less ...In this paper we use theoretical analysis and extensive simulations to study zone inhomogeneity with the random asymmetric simple exclusion process （ASEP）. In the inhomogeneous zone, the hopping probability is less than 1. Two typical lattice geometries are investigated here. In case A, the lattice includes two equal segments. The hopping probability in the left segment is equal to 1, and in the right segment it is equal to p, which is less than 1. In case B, there are three equal segments in the system; the hopping probabilities in the left and right segments are equal to 1, and in the middle segment it is equal to p, which is less than 1. Through theoretical analysis, we can discover the effect on these systems when p is changed.展开更多
In this paper, a kind of data analysis method is used to research the space time coherence of Xianshuihe fault zone in the process of seimogeny. It is proved that, the space time coherence of Xianshuihe fault zone, ...In this paper, a kind of data analysis method is used to research the space time coherence of Xianshuihe fault zone in the process of seimogeny. It is proved that, the space time coherence of Xianshuihe fault zone, in the process of seismogeny, really exists. The greater the earthquake magnitude of a fault section, the greater is its influence on the 'neighboring' sections. To a strike fault zone which bears compressive stress, the fault sections are 'series connected'. That is to say, once an earthquake happens on a fault section, the time of seismogeny in the neighboring fault sections will be shortened, therefore, this earthquake has 'an effect of hastening the occurrence of earthquakes in neighboring fault sections'. It is an inevitable rule for the Xianshuihe fault zone that the earthquake quiescent period and the earthquake active period occur alternatively. To the Xianshuihe fault zone, the slip predictable model does not tally with the actual situation, while the improved time predictable model tallies with the fact quite well. The data analysis method used here, which is used to examine the earthquake prediction models, is put forward on the basis of historical earthquake records. This kind of method and the relative conclusions have important reference value on the establishment of earthquake prediction models.展开更多
Wet coffee processing leads to the generation of large volumes of wastewater, whose discharge to the environment leads to pollution of freshwater bodies. Kayanza is a major coffee growing area in Burundi with more tha...Wet coffee processing leads to the generation of large volumes of wastewater, whose discharge to the environment leads to pollution of freshwater bodies. Kayanza is a major coffee growing area in Burundi with more than 40 wet coffee processing factories (WCPF) that discharge effluents directly to receiving water bodies without treatment. This study was carried out to assess the effect of coffee wastewater on the physicochemical properties of receiving waterbodies in Kayanza coffee growing ecological zone. Currently, no study has been done to analyze the effluent from the WCPF and assess the level of pollution. This study will therefore provide valuable data on the water pollution from coffee processing plants. Ten (10) rivers in the Kayanza coffee growing zone were studied during the months of April and June, 2020. Water samples were collected upstream (U) and downstream (D) of the effluent discharge points in triplicate. Samples were analyzed for pH, Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD<sub>5</sub>), Temperature, Salinity, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Dissolved Oxygen (DO), Total Suspended Solids (TSS), Nitrates, Nitrites, Lead (Pb), Copper (Cu), Chlorides and Ammonium ions using standard methods. <span style="letter-spacing:0.1pt;">Ph</span>ysical parameters were analyzed in situ whereas chemical param<span style="letter-spacing:0.1pt;">eters w</span><span style="letter-spacing:-0.05pt;">ere analy</span>zed in the laboratories in Burundi Institute of Agricultural Science<span style="letter-spacing:0.1pt;">s</span> (ISA<span style="letter-spacing:-0.2pt;">BU) and University of Burundi. Data were analyzed u</span>sing R-studio-1.0.153, GenStat 64-bit Release 14.1 and SSPS. Results on the physicochemical parameters indicated that coffee factory effluent has a polluting potential during coffee processing peak. The concentrations of the physicochemical parameters were significantly (p < 0.05) higher downstream (D) compared to upstream (U) of the river water sampling points. All downstream sites had COD, BOD<sub>5</sub>, TSS and pH values above allowable limits set by WHO and Burundi. The polluting impact of public wet coffee processing factories was significantly higher than that of private and cooperatives owned factories (p < 0.05). Measures should be taken in order to protect water bodies.展开更多
Since the similarity in size distribution of earthquakes and acoustic emissions （AE） was found in the 1960s, many laboratory studies have been motivated by the need to provide tools for the prediction of mining fail...Since the similarity in size distribution of earthquakes and acoustic emissions （AE） was found in the 1960s, many laboratory studies have been motivated by the need to provide tools for the prediction of mining failures and natural earthquakes. This paper aims, on the one hand, to draw an outline of laboratory AE studies in the last 50 years, which have addressed seismological problems. Topics include the power laws in which the similarity between AEs and earthquakes is involved and progress that has been made in AE technology and laboratory AE study. On the other hand, this study will highlight some key issues intensively discussed, especially in the last three decades, such as aspects related to the pre-failure damage evolution, fault nucleation and growth in brittle rocks and discuss factors governing these processes.展开更多
基金funded by the National Natural Science Foundation of China(Grant Nos.12172230,U22A20166)the Department of Science and Technology of Guangdong Province(Grant No.2019ZT08G315).
文摘Understanding the anisotropic fracture behavior and the characteristics of the fracture process zone(FPZ)under size effects in laminated rocks,as well as its role in rock fracturing,is crucial for various engineering applications.In this study,three-point bending tests were conducted on shale specimens with varying bedding angles and sizes.The anisotropic characteristics and size effects of fracture parameters were revealed.A comparative analysis was performed on the evolutions of FPZs computed using size effect theory,digital image correlation(DIC),and linear elastic fracture mechanics.The results divulged that:(i)With increasing bedding angles,there is a noticeable decrease in apparent fracture toughness(KICA),apparent fracture energy(GICA),and nominal strength(σ_(Nu)).When the bedding angle of shale is less than 45°,the crack propagation and fracture parameters are mainly influenced by the matrix.Contrary,shale with bedding angles greater than 60°,the crack propagation and fracture parameters are mainly controlled by the bedding.When the bedding angle is between 45°and 60°,the fracture propagation evolves from permeating the matrix to extending along the bedding;(ii)The fracture parameters exhibit significant size dependent behavior,as KICA and GICA rise with increasing specimen size,butσNu falls with increasing specimen sizes.The fracture parameters align with the theoretical predictions of Bažant size effect law;and(iii)The lengths of DIC-based FPZ,effective FPZ,and inelastic zone follow W-shape variations with bedding angle.The dimensionless sizes of FPZ and inelastic zone decrease with specimen size,indicating a size effect.Furthermore,there is a negative relation between KICA and the dimensionless size of the FPZ,whileσNu is positively correlated to the dimensionless size of the FPZ.This highlights the essential role of the FPZ in the size effect of rock fracture.The bedding angle exerts an influence on the FPZ,subsequently affecting the anisotropic fracture and size-dependent behavior of shale.
基金supported by the projects(Grant No.:52304118)supported by National Natural Science Foundation of China,the Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology(2023yjrc18)the Open Fund of the State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine(Grant No.:SKLMRDPC23KF08).
文摘This study investigates the fracture characteristics and the fracture process zone(FPZ)of mode I fracture in sandstone,aiming to analyze the propagation behaviors of mode I crack under different freeze-thaw cycles.Semicircular bending tests(SCB)were conducted using different freeze-thaw cycles to evaluate mode I fracture toughness,FPZ dynamics,and macroscopic microscopic features.Digital image correlation(DIC)and scanning electron microscopy(SEM)techniques were employed for detailed analysis.Experimental results reveal that freeze-thaw cycling leads to the widening of both preexisting and newly formed microcracks between internal particles.Under external loading,crack propagation deviates from prefabricated paths,forming serrated crack patterns.The FPZ initiates at the prefabricated crack tip and extends toward the loading end,exhibiting an arcshaped tip shape.The FPZ length increases with loading but decreases after reaching a peak value.With additional freeze-thaw cycles,the maximum FPZ length first increases and then diminishes.
基金Project(50274074) supported by the National Natural Science Foundation of China project(04JJ6030) supported by theNatural Science Foundation of Hunan Province
文摘An analytical expression for the prediction of shear-compressive fracture process zone(SCFPZ) is derived by using a proposed local strain energy density criterion, in which the strain energy density is separated into the dilatational and distortional strain energy density, only the former is considered to contribute to the brittle fracture of rock in different loading cases. The theoretical prediction by this criterion shows that the SCFPZ is of asymmetric mulberry leaf in shape, which forms a shear-compression fracture kern. Dilatational strain energy density along the boundary of SCFPZ reaches its maximum value. The dimension of SCFPZ is governed by the ratio of K_Ⅱ to (K_Ⅰ.) The analytical results are then compared with those from literatures and the tests conducted on double edge cracked Brazilian disk subjected to diametrical compression. The obtained results are useful to the prediction of crack extension and to nonlinear analysis of shear-compressive fracture of brittle rock.
文摘On the basis of that rock material usually has a larger fracture process zone,a new fracture criterion which is different from that of linear elastic fracture theory was presented.On this basis,the fracture behavior and influencing factors under modeⅡor compressive shear loading were investigated.
文摘Two pollution zones in middle and lower reaches of Hanjiang River were selected for studying restoration processes. In each zones 6 stations were set up in upper stream of sewage outfall, 50m, 100 or 150m, 250 or 525m and 1250 or 3500m apart from the outfall. Chemical monitoring and microbial community biomonitoring were carried out simultaneously. Either the chemical monitoring or the biological monitoring proved the self-purification process of water body along with the increased distance from the sewage outfall. 4 biological parameters (species number of protozoa, percentage of phytomastigophora, diversity index and heterotrophy index) and parameter Seq of the colonization process all have statistically significant correlations with chemical comprehensive pollution indexes Pa and Pb.
文摘Three-dimensional thermal a nalysis simulation of a horizontal zone refining system is conducted for germanimn semiconductor materials. The considered geometry includes a g＇ral）hite boat filled with germanium placed in a cylindrical quartz tube. A flow of Ar and H2 gas mixture is purged througll the tube. A narrow section of the, boat is assmned to be exposed to a constant heat rate produced b v an rf coil located outside the quartz tube. The results of this analysis provide essential information about various parameters such as the shape of tile molten zone, required power and temperature gradient in the system.
文摘At present, the international economy continues growing slowly, and the foreign trade situation is not optimistic. In addition, domestic demand are strongly encouraged and expanded in China. Compared with a prosperous domestic market, enterprises in the export processing zone have few advantages. Domestic sales have become an inevitable trend. It is also beneficial for the transformation and upgrading of export processing zone. However, it is quite difficult to open up the domestic market for export-oriented enterprises in the area. They will encounter many obstacles. The government and enterprises should take appropriate measures to facilitate the enterprise to turn export to domestic sales.
基金Project supported by the State Key Program for Basic Research of China (Grant No 2005CB724206)
文摘In this paper we use theoretical analysis and extensive simulations to study zone inhomogeneity with the random asymmetric simple exclusion process （ASEP）. In the inhomogeneous zone, the hopping probability is less than 1. Two typical lattice geometries are investigated here. In case A, the lattice includes two equal segments. The hopping probability in the left segment is equal to 1, and in the right segment it is equal to p, which is less than 1. In case B, there are three equal segments in the system; the hopping probabilities in the left and right segments are equal to 1, and in the middle segment it is equal to p, which is less than 1. Through theoretical analysis, we can discover the effect on these systems when p is changed.
文摘In this paper, a kind of data analysis method is used to research the space time coherence of Xianshuihe fault zone in the process of seimogeny. It is proved that, the space time coherence of Xianshuihe fault zone, in the process of seismogeny, really exists. The greater the earthquake magnitude of a fault section, the greater is its influence on the 'neighboring' sections. To a strike fault zone which bears compressive stress, the fault sections are 'series connected'. That is to say, once an earthquake happens on a fault section, the time of seismogeny in the neighboring fault sections will be shortened, therefore, this earthquake has 'an effect of hastening the occurrence of earthquakes in neighboring fault sections'. It is an inevitable rule for the Xianshuihe fault zone that the earthquake quiescent period and the earthquake active period occur alternatively. To the Xianshuihe fault zone, the slip predictable model does not tally with the actual situation, while the improved time predictable model tallies with the fact quite well. The data analysis method used here, which is used to examine the earthquake prediction models, is put forward on the basis of historical earthquake records. This kind of method and the relative conclusions have important reference value on the establishment of earthquake prediction models.
文摘Wet coffee processing leads to the generation of large volumes of wastewater, whose discharge to the environment leads to pollution of freshwater bodies. Kayanza is a major coffee growing area in Burundi with more than 40 wet coffee processing factories (WCPF) that discharge effluents directly to receiving water bodies without treatment. This study was carried out to assess the effect of coffee wastewater on the physicochemical properties of receiving waterbodies in Kayanza coffee growing ecological zone. Currently, no study has been done to analyze the effluent from the WCPF and assess the level of pollution. This study will therefore provide valuable data on the water pollution from coffee processing plants. Ten (10) rivers in the Kayanza coffee growing zone were studied during the months of April and June, 2020. Water samples were collected upstream (U) and downstream (D) of the effluent discharge points in triplicate. Samples were analyzed for pH, Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD<sub>5</sub>), Temperature, Salinity, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Dissolved Oxygen (DO), Total Suspended Solids (TSS), Nitrates, Nitrites, Lead (Pb), Copper (Cu), Chlorides and Ammonium ions using standard methods. <span style="letter-spacing:0.1pt;">Ph</span>ysical parameters were analyzed in situ whereas chemical param<span style="letter-spacing:0.1pt;">eters w</span><span style="letter-spacing:-0.05pt;">ere analy</span>zed in the laboratories in Burundi Institute of Agricultural Science<span style="letter-spacing:0.1pt;">s</span> (ISA<span style="letter-spacing:-0.2pt;">BU) and University of Burundi. Data were analyzed u</span>sing R-studio-1.0.153, GenStat 64-bit Release 14.1 and SSPS. Results on the physicochemical parameters indicated that coffee factory effluent has a polluting potential during coffee processing peak. The concentrations of the physicochemical parameters were significantly (p < 0.05) higher downstream (D) compared to upstream (U) of the river water sampling points. All downstream sites had COD, BOD<sub>5</sub>, TSS and pH values above allowable limits set by WHO and Burundi. The polluting impact of public wet coffee processing factories was significantly higher than that of private and cooperatives owned factories (p < 0.05). Measures should be taken in order to protect water bodies.
基金financial support by the Japan Science Promotion Society(JSPS 21246134)
文摘Since the similarity in size distribution of earthquakes and acoustic emissions （AE） was found in the 1960s, many laboratory studies have been motivated by the need to provide tools for the prediction of mining failures and natural earthquakes. This paper aims, on the one hand, to draw an outline of laboratory AE studies in the last 50 years, which have addressed seismological problems. Topics include the power laws in which the similarity between AEs and earthquakes is involved and progress that has been made in AE technology and laboratory AE study. On the other hand, this study will highlight some key issues intensively discussed, especially in the last three decades, such as aspects related to the pre-failure damage evolution, fault nucleation and growth in brittle rocks and discuss factors governing these processes.
