By taking Youxi Village which was the typical village with wooden arched bridges in East Fujian for example, it had discussed landforms, geology, soil, climate and vegetation in natural environment which could be perc...By taking Youxi Village which was the typical village with wooden arched bridges in East Fujian for example, it had discussed landforms, geology, soil, climate and vegetation in natural environment which could be perceived and village's cultural and historical background. Based on relevant research results in academic field, it had studied the relationship between wooden arched bridges and villages' environment in East Fujian, and further analyzed the relation of wooden arched bridges as traditional architectural heritages with village's living condition and history. On this basis, it had analyzed imaginability of natural environment of Youxi Village from the aspects of village's site and stream's trend, and imaginability of cultural environment by taking Wenming Bridge, Liren Bridge and Zhangkeng Bridge for example. It was considered that wooden arched bridge was the consolidation of natural environment and had been the recognizable image at villages of East Fujian, manifesting heavy cultural characteristic.展开更多
To study the influence of axial stress on the failure characteristics of deep arched roadway considering structural effect,true triaxial compression tests were conducted on cubic granite specimens with a three-centere...To study the influence of axial stress on the failure characteristics of deep arched roadway considering structural effect,true triaxial compression tests were conducted on cubic granite specimens with a three-centered arched hole structure.A video monitoring device was utilized to record the failure process of surrounding rocks.The test results show that under 10−60 MPa axial stress,the surrounding rock failure process included the calm stage,particle ejection stage,fragment ejection stage,and rock slice buckling and spalling stage.Under higher axial stresses(70 and 80 MPa),the failure process is characterized by violent fragment spray during the fourth stage.As the axial stress increases,the failure of surrounding rock increases,while the initial vertical failure stress first increases and then decreases.According to the failure characteristics of roadway under different axial stresses,arranging the roadway along the direction of a moderate axial stress level is desired.展开更多
The red beds in Zhejiang province of China host the highest concentration of Danxia arched rock shelters in the world,just as the Colorado Plateau in the western USA hosts the world's largest concentration of natu...The red beds in Zhejiang province of China host the highest concentration of Danxia arched rock shelters in the world,just as the Colorado Plateau in the western USA hosts the world's largest concentration of natural arches and bridges.This study investigated the geological background of the arched rock shelters and compared them to the natural arches and bridges,based on field study and a literature review.It was found that Zhejiang arched rock shelters differ from Colorado Plateau natural arches and bridges in geometry and formation mechanism.Statistical geometric data on arch geometry shows that Danxia arched rock shelters in Zhejiang tend to be relatively flat.They are relatively low features with long spans,and great depth.The natural arches and bridges on the Colorado Plateau are similar to each other,but the bridges are larger than the arches.The geometric differences between the arched landforms could be attributed to their different geologic history and to their different formation mechanisms.The arched rock shelters in Zhejiang are formed by differential weathering between sandstone and conglomerate due to moisture-induced tensile stresses.In contrast,natural arches on the Colorado Plateau are closely related to the Salt Valley anticline,vertical tectonic fractures,and horizontal discontinuities in rock fins.The Colorado Plateau natural bridges were formed by river erosion.展开更多
Current practice in analysis and design of blast doors subjected to blast loading considers only simple boundary conditions and material properties. The boundary conditions and material properties, in fact, have consi...Current practice in analysis and design of blast doors subjected to blast loading considers only simple boundary conditions and material properties. The boundary conditions and material properties, in fact, have considerable influence on the response of blast doors subjected to blast loading. In this paper, the dynamic responses of a reinforced concrete arched blast door under blast loading were analyzed by the finite element program ABAQUS, combined with a previously developed elasto-viscoplastic rate-sensitive material model. And the effect of the surrounding rock mass and contact effect of the doorframe were also taken into account in the simulation. It is demonstrated that the strain-rate effect has considerable influence on the response of reinforced concrete blast door subjected to blast loading and must be taken into account in the analysis.展开更多
This work presents the hydrologic estimations of the hydraulic underground arched culvert channel (UACC) in Sabinal Basin, Chiapas, México and the hydrological problems associated with it, such as the erosion phe...This work presents the hydrologic estimations of the hydraulic underground arched culvert channel (UACC) in Sabinal Basin, Chiapas, México and the hydrological problems associated with it, such as the erosion phenomenon and abrasion cavity formation in it. On the other hand, the maximum flows that the UACC could transport were analyzed, concluding that it no longer has the hydraulic capacity to transport the flow rate associated to return periods equal to or greater than five years and that maximum permissible velocity UACC’s bottom is 3 m/s.展开更多
High-pile and beam-slab quays have been widely used after several years development. They are mature enough to be one of the most important structural types of wharves in China coastal areas. In order to accommodate l...High-pile and beam-slab quays have been widely used after several years development. They are mature enough to be one of the most important structural types of wharves in China coastal areas. In order to accommodate large tonnage vessels, wharves should be eorrstructed in deep water gradually. However, conventional high-pile and beam-slab structares are hard to meet the requirements of large deep-water wharf. According to arch＇ s stress characteristics, a new type of wharf with catenary arched longitudinal beams is presented in this paper. The new wharf structure can make full use of arch＇s overhead crossing and reinforced concrete compression resistance, improve the interval between transverse bents greatly, and decrease underwater construction quantity. Thus, the construction cost cab be reduced. Take the third phase project of the Yangshan Deep-water Port for example, comparative analysis on catenary arched longitudinal beams and conventional longitudinal beams has been made. The result shows that with the same wharf length and width, the same loads and same longitudinal beam moment, catenary arch structure can improve the interval between bents up to 28 m, decrease the nmnber of piles and underwater construction quantity.展开更多
The Podilskyi Arch bridge is crossing the Dnipro River in center of Kiev and is part of a 7.4 km long link which connects the center of Kiev with the “sleeping district” on the left bank of the river. The bridge has...The Podilskyi Arch bridge is crossing the Dnipro River in center of Kiev and is part of a 7.4 km long link which connects the center of Kiev with the “sleeping district” on the left bank of the river. The bridge has a main span of 344 m intended for six lanes of vehicles in the top level and two metro lines in the bottom level plus large diameter water pipes. The bridge is of steel, except of the reinforced concrete bases of the lower parts of the arches. The draft design works began in 1991 and in 2005 parallel design and construction work started. Due to the financial crisis in Ukraine, the work was interrupted for several years but construction recommenced in 2018 and the bridge is now planned to be completed in 2020 and the first stage of the transition in 2022.展开更多
With the current rapid development of urbanization in China,people's living standards have been greatly improved.In the context of such a development background,the requirements for road traffic are getting more s...With the current rapid development of urbanization in China,people's living standards have been greatly improved.In the context of such a development background,the requirements for road traffic are getting more stringent,especially for bridge projects.The arched continuous rigid-frame bridge was developed under this social background.The advantage of the bridge lies in the design of a bridge model that integrates various functions such as transportation,landscape,and sightseeing.Based on the above,this paper first refers to the case to analyze the design and construction strategy of the arched continuous rigid-frame bridge,in hope of providing a valuable reference for relevant personnel.展开更多
The contact deformation and buckling of elastic rods against rigid surfaces represent a prevalent phenomenon in applications such as oil drilling,arterial stents,and energy harvesting.This has attracted widespread att...The contact deformation and buckling of elastic rods against rigid surfaces represent a prevalent phenomenon in applications such as oil drilling,arterial stents,and energy harvesting.This has attracted widespread attention from researchers.In this paper,the deformation and buckling behaviors of a circular arch subject to compression by a rigid plate are investigated with a planar elastic rod model that incorporates tension,shearing,and bending.In comparison with the existing models that solely consider the bending energy,the deflection curve,the internal force distribution,and the critical load of the present model show good agreement with the finite element results.Through the dimensional analysis and order-of-magnitude estimation,we examine the factors influencing the critical load.The study reveals that the semi-central angle of the arch has the most significant effect.The dimensionless geometric parameter describing arch slenderness becomes prominent when the semi-central angle is less than 30°,while Poisson's ratio and the cross-sectional shear correction factor exhibit negligible influence.Furthermore,the variation in the proportions of strain energy components during critical buckling is presented with respect to the semi-central angle and the geometric parameter,thereby delineating the applicable ranges of both the original model(OM)and the modified model(MM).展开更多
Deformation prediction for extra-high arch dams is highly important for ensuring their safe operation.To address the challenges of complex monitoring data,the uneven spatial distribution of deformation,and the constru...Deformation prediction for extra-high arch dams is highly important for ensuring their safe operation.To address the challenges of complex monitoring data,the uneven spatial distribution of deformation,and the construction and optimization of a prediction model for deformation prediction,a multipoint ultrahigh arch dam deformation prediction model,namely,the CEEMDAN-KPCA-GSWOA-KELM,which is based on a clustering partition,is pro-posed.First,the monitoring data are preprocessed via variational mode decomposition(VMD)and wavelet denoising(WT),which effectively filters out noise and improves the signal-to-noise ratio of the data,providing high-quality input data for subsequent prediction models.Second,scientific cluster partitioning is performed via the K-means++algorithm to precisely capture the spatial distribution characteristics of extra-high arch dams and ensure the consistency of deformation trends at measurement points within each partition.Finally,CEEMDAN is used to separate monitoring data,predict and analyze each component,combine the KPCA(Kernel Principal Component Analysis)and the KELM(Kernel Extreme Learning Machine)optimized by the GSWOA(Global Search Whale Optimization Algorithm),integrate the predictions of each component via reconstruction methods,and precisely predict the overall trend of ultrahigh arch dam deformation.An extra high arch dam project is taken as an example and validated via a comparative analysis of multiple models.The results show that the multipoint deformation prediction model in this paper can combine data from different measurement points,achieve a comprehensive,precise prediction of the deformation situation of extra high arch dams,and provide strong technical support for safe operation.展开更多
In this paper,the collapse dynamic properties of the cylindrical bubble near an arched cylinder bulge are researched relying on the conformal transformation and Kelvin impulse model.The properties of the liquid veloci...In this paper,the collapse dynamic properties of the cylindrical bubble near an arched cylinder bulge are researched relying on the conformal transformation and Kelvin impulse model.The properties of the liquid velocity distribution,Kelvin impulse distribution and the attraction zone of the jet are analyzed when the bubble and the bulge are arranged symmetrically and asymmetrically.The results show that,firstly,on the side of the bubble close to the bulge,there is a minimum collapse velocity of the bubble surface,which decreases as the bulge angle increases.In addition,the bulge’s effects on the Kelvin impulse strength and direction become larger as the bulge angle increases.When the bubble is incepted at the joint of the flat wall and the bulge,the impulse strength reaches its maximum.Finally,as the bulge angle increases from 45°–120°,the area of the jet attraction zone is gradually expanding,with its maximum width gradually increasing from 1.1–1.8 times the chord length of the bulge.展开更多
The stability of underground tunnel roofs is strongly influenced by wedge blocks formed by complex joint networks.The mechanical behavior and failure mechanisms of different roof wedge blocks in arched holes were inve...The stability of underground tunnel roofs is strongly influenced by wedge blocks formed by complex joint networks.The mechanical behavior and failure mechanisms of different roof wedge blocks in arched holes were investigated under biaxial stress conditions.The crack evolution and failure modes of the specimens were analyzed through acoustic emission(AE),digital image correlation(DIC),and discrete element method(DEM).Results show significant variations in mechanical properties:specimens T1(extremely unstable triangular)and T2(extremely unstable quadrilateral)exhibited higher strength than T3(extremely stable triangular)and T4(extremely stable quadrilateral),while support more effectively enhanced the strength of T3 and T4.Failure modes were classified as rock-dominated,wedgedominated,or co-dominated.Cracks typically initiated near the wedge and propagated outward.Unsupported specimens developed tensile cracks at the hole bottom,shear cracks at the sides,and mixed cracks along wedge boundaries,whereas supported specimens mainly exhibited cracks at the roof and sides.Stress analysis indicated that unsupported conditions induced high stress differences,promoting localized shear failure.Wedge geometry significantly affected shear stress redistribution at the roof.These findings highlight the critical role of support and wedge block geometry in controlling stress dis-tribution and failure mechanisms in arched tunnels.展开更多
Determining earth pressure on jacked pipes is essential for ensuring lining safety and calculating jacking force,especially for deep-buried pipes.To better reflect the soil arching effect resulting from the excavation...Determining earth pressure on jacked pipes is essential for ensuring lining safety and calculating jacking force,especially for deep-buried pipes.To better reflect the soil arching effect resulting from the excavation of rectangular jacked pipes and the distribution of the earth pressure on jacked pipes,we present an analytical solution for predicting the vertical earth pressure on deep-buried rectangular pipe jacking tunnels,incorporating the tunnelling-induced ground loss distribution.Our proposed analytical model consists of the upper multi-layer parabolic soil arch and the lower friction arch.The key parameters(i.e.,width and height of friction arch B and height of parabolic soil arch H 1)are determined according to the existing research,and an analytical solution for K l is derived based on the distribution characteristics of the principal stress rotation angle.With consideration for the transition effect of the mechanical characteristics of the parabolic arch zone,an analytical solution for soil load transfer is derived.The prediction results of our analytical solution are compared with tests and simulation results to validate the effectiveness of the proposed analytical solution.Finally,the effects of different parameters on the soil pressure are discussed.展开更多
Introduction Aortic arch anomalies are congenital malformations of the position or branching of the aortic arch,or both.Double aortic arch(DAA)is a very rare malformation,affecting approximately 0.005%~0.007% of fetus...Introduction Aortic arch anomalies are congenital malformations of the position or branching of the aortic arch,or both.Double aortic arch(DAA)is a very rare malformation,affecting approximately 0.005%~0.007% of fetuses[1],and there has been no relevant literature mentioning the prenatal finding DAA in Macao till now.展开更多
Hydrogel has developed into a very important platform in solar interface evaporator.However,the current hydrogel evaporators are usually three-dimensional evaporators,which will consume a lot of raw materials.Thus,a n...Hydrogel has developed into a very important platform in solar interface evaporator.However,the current hydrogel evaporators are usually three-dimensional evaporators,which will consume a lot of raw materials.Thus,a new two-dimensional hydrogel evaporator is urgently needed to alleviate this problem.Here,a double layer hydrogel evaporator was designed by twice vacuum filtration.Furthermore,through the arched design and the introduction of concentrated brine drainage system,the hydrogel evaporator has enhanced water transportation and tailored water transportation path.Such a unique drainage evaporation system greatly improves the stability of the evaporator.Thereby,a good balance is established between photothermal conversion and water supply,and solar energy is utilized efficiently.It can remain stable in continuous evaporation for up to 12 h with an excellent evaporation rate of 2.70 kg m^(-2)h^(-1)under 1 sun irradiation.Meanwhile,the drainage system realized the 1.8×10^(-10)mol m^(-2)s^(-1)diffusion flux of concentrated brine.Through one-time freeze-drying preparation,an arch-shaped drainage evaporator was used to prepare an evaporation area of more than 20 cm^(2).With the self-made condensate collecting device in outdoor environment,the fresh water yield reaches 7.5 L m^(-2)d^(-1).This provides a new scheme for building a new hydrogel evaporator and solving the fresh water crisis.展开更多
基金Supported by the subject of " Professor Cultivation Engineering" of Ningde Teachers College of 2010 (2010J002)the special subject of " Cultural Research of East Fujian" in 2011 (2011HW05)A Class Subject of Fujian Department Education (JA11300S)~~
文摘By taking Youxi Village which was the typical village with wooden arched bridges in East Fujian for example, it had discussed landforms, geology, soil, climate and vegetation in natural environment which could be perceived and village's cultural and historical background. Based on relevant research results in academic field, it had studied the relationship between wooden arched bridges and villages' environment in East Fujian, and further analyzed the relation of wooden arched bridges as traditional architectural heritages with village's living condition and history. On this basis, it had analyzed imaginability of natural environment of Youxi Village from the aspects of village's site and stream's trend, and imaginability of cultural environment by taking Wenming Bridge, Liren Bridge and Zhangkeng Bridge for example. It was considered that wooden arched bridge was the consolidation of natural environment and had been the recognizable image at villages of East Fujian, manifesting heavy cultural characteristic.
基金supported by the National Key Research and Development Program of China-2023 Key Special Project(No.2023YFC_(2)907400)the Hunan Provincial Natural Science Foundation for Distinguished Young Scholars,China(No.2023JJ10072)+1 种基金the Science and Technology Innovation Program of Hunan Province,China(No.2022RC1173)the Fundamental Research Funds for the Central Universities of Central South University,China(No.2023ZZTS0499).
文摘To study the influence of axial stress on the failure characteristics of deep arched roadway considering structural effect,true triaxial compression tests were conducted on cubic granite specimens with a three-centered arched hole structure.A video monitoring device was utilized to record the failure process of surrounding rocks.The test results show that under 10−60 MPa axial stress,the surrounding rock failure process included the calm stage,particle ejection stage,fragment ejection stage,and rock slice buckling and spalling stage.Under higher axial stresses(70 and 80 MPa),the failure process is characterized by violent fragment spray during the fourth stage.As the axial stress increases,the failure of surrounding rock increases,while the initial vertical failure stress first increases and then decreases.According to the failure characteristics of roadway under different axial stresses,arranging the roadway along the direction of a moderate axial stress level is desired.
基金National Natural Science Foundation of China,No.41372322。
文摘The red beds in Zhejiang province of China host the highest concentration of Danxia arched rock shelters in the world,just as the Colorado Plateau in the western USA hosts the world's largest concentration of natural arches and bridges.This study investigated the geological background of the arched rock shelters and compared them to the natural arches and bridges,based on field study and a literature review.It was found that Zhejiang arched rock shelters differ from Colorado Plateau natural arches and bridges in geometry and formation mechanism.Statistical geometric data on arch geometry shows that Danxia arched rock shelters in Zhejiang tend to be relatively flat.They are relatively low features with long spans,and great depth.The natural arches and bridges on the Colorado Plateau are similar to each other,but the bridges are larger than the arches.The geometric differences between the arched landforms could be attributed to their different geologic history and to their different formation mechanisms.The arched rock shelters in Zhejiang are formed by differential weathering between sandstone and conglomerate due to moisture-induced tensile stresses.In contrast,natural arches on the Colorado Plateau are closely related to the Salt Valley anticline,vertical tectonic fractures,and horizontal discontinuities in rock fins.The Colorado Plateau natural bridges were formed by river erosion.
基金Supported by National Natural Science Foundation of China(No.50525825)
文摘Current practice in analysis and design of blast doors subjected to blast loading considers only simple boundary conditions and material properties. The boundary conditions and material properties, in fact, have considerable influence on the response of blast doors subjected to blast loading. In this paper, the dynamic responses of a reinforced concrete arched blast door under blast loading were analyzed by the finite element program ABAQUS, combined with a previously developed elasto-viscoplastic rate-sensitive material model. And the effect of the surrounding rock mass and contact effect of the doorframe were also taken into account in the simulation. It is demonstrated that the strain-rate effect has considerable influence on the response of reinforced concrete blast door subjected to blast loading and must be taken into account in the analysis.
文摘This work presents the hydrologic estimations of the hydraulic underground arched culvert channel (UACC) in Sabinal Basin, Chiapas, México and the hydrological problems associated with it, such as the erosion phenomenon and abrasion cavity formation in it. On the other hand, the maximum flows that the UACC could transport were analyzed, concluding that it no longer has the hydraulic capacity to transport the flow rate associated to return periods equal to or greater than five years and that maximum permissible velocity UACC’s bottom is 3 m/s.
基金supported bythe National Natural Science Foundation of China(Grant No.40776053)
文摘High-pile and beam-slab quays have been widely used after several years development. They are mature enough to be one of the most important structural types of wharves in China coastal areas. In order to accommodate large tonnage vessels, wharves should be eorrstructed in deep water gradually. However, conventional high-pile and beam-slab structares are hard to meet the requirements of large deep-water wharf. According to arch＇ s stress characteristics, a new type of wharf with catenary arched longitudinal beams is presented in this paper. The new wharf structure can make full use of arch＇s overhead crossing and reinforced concrete compression resistance, improve the interval between transverse bents greatly, and decrease underwater construction quantity. Thus, the construction cost cab be reduced. Take the third phase project of the Yangshan Deep-water Port for example, comparative analysis on catenary arched longitudinal beams and conventional longitudinal beams has been made. The result shows that with the same wharf length and width, the same loads and same longitudinal beam moment, catenary arch structure can improve the interval between bents up to 28 m, decrease the nmnber of piles and underwater construction quantity.
文摘The Podilskyi Arch bridge is crossing the Dnipro River in center of Kiev and is part of a 7.4 km long link which connects the center of Kiev with the “sleeping district” on the left bank of the river. The bridge has a main span of 344 m intended for six lanes of vehicles in the top level and two metro lines in the bottom level plus large diameter water pipes. The bridge is of steel, except of the reinforced concrete bases of the lower parts of the arches. The draft design works began in 1991 and in 2005 parallel design and construction work started. Due to the financial crisis in Ukraine, the work was interrupted for several years but construction recommenced in 2018 and the bridge is now planned to be completed in 2020 and the first stage of the transition in 2022.
文摘With the current rapid development of urbanization in China,people's living standards have been greatly improved.In the context of such a development background,the requirements for road traffic are getting more stringent,especially for bridge projects.The arched continuous rigid-frame bridge was developed under this social background.The advantage of the bridge lies in the design of a bridge model that integrates various functions such as transportation,landscape,and sightseeing.Based on the above,this paper first refers to the case to analyze the design and construction strategy of the arched continuous rigid-frame bridge,in hope of providing a valuable reference for relevant personnel.
基金Project supported by the National Natural Science Foundation of China(Nos.124B2043,U2241267,12172155,and 12302278)the Science and Technology Leading Talent Project of Gansu Province of China(No.23ZDKA0009)the Natural Science Foundation of Gansu Province of China(Nos.24JRRA473 and 24JRRA489)。
文摘The contact deformation and buckling of elastic rods against rigid surfaces represent a prevalent phenomenon in applications such as oil drilling,arterial stents,and energy harvesting.This has attracted widespread attention from researchers.In this paper,the deformation and buckling behaviors of a circular arch subject to compression by a rigid plate are investigated with a planar elastic rod model that incorporates tension,shearing,and bending.In comparison with the existing models that solely consider the bending energy,the deflection curve,the internal force distribution,and the critical load of the present model show good agreement with the finite element results.Through the dimensional analysis and order-of-magnitude estimation,we examine the factors influencing the critical load.The study reveals that the semi-central angle of the arch has the most significant effect.The dimensionless geometric parameter describing arch slenderness becomes prominent when the semi-central angle is less than 30°,while Poisson's ratio and the cross-sectional shear correction factor exhibit negligible influence.Furthermore,the variation in the proportions of strain energy components during critical buckling is presented with respect to the semi-central angle and the geometric parameter,thereby delineating the applicable ranges of both the original model(OM)and the modified model(MM).
基金supported by the National Natural Science Foundation of China(Grant Nos.52069029,52369026)the Belt and Road Special Foundation of National Key Laboratory of Water Disaster Preven-tion(Grant No.2023490411)+2 种基金the Yunnan Agricultural Basic Research Joint Special General Project(Grant Nos.202501BD070001-060,202401BD070001-071)Construction Project of the Yunnan Key Laboratory of Water Security(No.20254916CE340051)the Youth Talent Project of“Xingdian Talent Support Plan”in Yunnan Province(Grant No.XDYC-QNRC-2023-0412).
文摘Deformation prediction for extra-high arch dams is highly important for ensuring their safe operation.To address the challenges of complex monitoring data,the uneven spatial distribution of deformation,and the construction and optimization of a prediction model for deformation prediction,a multipoint ultrahigh arch dam deformation prediction model,namely,the CEEMDAN-KPCA-GSWOA-KELM,which is based on a clustering partition,is pro-posed.First,the monitoring data are preprocessed via variational mode decomposition(VMD)and wavelet denoising(WT),which effectively filters out noise and improves the signal-to-noise ratio of the data,providing high-quality input data for subsequent prediction models.Second,scientific cluster partitioning is performed via the K-means++algorithm to precisely capture the spatial distribution characteristics of extra-high arch dams and ensure the consistency of deformation trends at measurement points within each partition.Finally,CEEMDAN is used to separate monitoring data,predict and analyze each component,combine the KPCA(Kernel Principal Component Analysis)and the KELM(Kernel Extreme Learning Machine)optimized by the GSWOA(Global Search Whale Optimization Algorithm),integrate the predictions of each component via reconstruction methods,and precisely predict the overall trend of ultrahigh arch dam deformation.An extra high arch dam project is taken as an example and validated via a comparative analysis of multiple models.The results show that the multipoint deformation prediction model in this paper can combine data from different measurement points,achieve a comprehensive,precise prediction of the deformation situation of extra high arch dams,and provide strong technical support for safe operation.
基金financially supported by the Postdoctoral Fellowship Program of CPSF(Grant No.GZC20240466).
文摘In this paper,the collapse dynamic properties of the cylindrical bubble near an arched cylinder bulge are researched relying on the conformal transformation and Kelvin impulse model.The properties of the liquid velocity distribution,Kelvin impulse distribution and the attraction zone of the jet are analyzed when the bubble and the bulge are arranged symmetrically and asymmetrically.The results show that,firstly,on the side of the bubble close to the bulge,there is a minimum collapse velocity of the bubble surface,which decreases as the bulge angle increases.In addition,the bulge’s effects on the Kelvin impulse strength and direction become larger as the bulge angle increases.When the bubble is incepted at the joint of the flat wall and the bulge,the impulse strength reaches its maximum.Finally,as the bulge angle increases from 45°–120°,the area of the jet attraction zone is gradually expanding,with its maximum width gradually increasing from 1.1–1.8 times the chord length of the bulge.
基金the National Natural Science Foundation of China(No.52374150)the Key Science and Technology Project of Ministry of Emergency Management of the People’s Republic of China(No.2024EMST141405).
文摘The stability of underground tunnel roofs is strongly influenced by wedge blocks formed by complex joint networks.The mechanical behavior and failure mechanisms of different roof wedge blocks in arched holes were investigated under biaxial stress conditions.The crack evolution and failure modes of the specimens were analyzed through acoustic emission(AE),digital image correlation(DIC),and discrete element method(DEM).Results show significant variations in mechanical properties:specimens T1(extremely unstable triangular)and T2(extremely unstable quadrilateral)exhibited higher strength than T3(extremely stable triangular)and T4(extremely stable quadrilateral),while support more effectively enhanced the strength of T3 and T4.Failure modes were classified as rock-dominated,wedgedominated,or co-dominated.Cracks typically initiated near the wedge and propagated outward.Unsupported specimens developed tensile cracks at the hole bottom,shear cracks at the sides,and mixed cracks along wedge boundaries,whereas supported specimens mainly exhibited cracks at the roof and sides.Stress analysis indicated that unsupported conditions induced high stress differences,promoting localized shear failure.Wedge geometry significantly affected shear stress redistribution at the roof.These findings highlight the critical role of support and wedge block geometry in controlling stress dis-tribution and failure mechanisms in arched tunnels.
基金Project(2022YJS073)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2024YFE0198500)supported by the National Key Research and Development Program of China:Intergovernmental International Science and Technology Innovation CooperationProject(U2469207)supported by the National Natural Science Foundation Railway Innovation and Development Joint Fund Project,China。
文摘Determining earth pressure on jacked pipes is essential for ensuring lining safety and calculating jacking force,especially for deep-buried pipes.To better reflect the soil arching effect resulting from the excavation of rectangular jacked pipes and the distribution of the earth pressure on jacked pipes,we present an analytical solution for predicting the vertical earth pressure on deep-buried rectangular pipe jacking tunnels,incorporating the tunnelling-induced ground loss distribution.Our proposed analytical model consists of the upper multi-layer parabolic soil arch and the lower friction arch.The key parameters(i.e.,width and height of friction arch B and height of parabolic soil arch H 1)are determined according to the existing research,and an analytical solution for K l is derived based on the distribution characteristics of the principal stress rotation angle.With consideration for the transition effect of the mechanical characteristics of the parabolic arch zone,an analytical solution for soil load transfer is derived.The prediction results of our analytical solution are compared with tests and simulation results to validate the effectiveness of the proposed analytical solution.Finally,the effects of different parameters on the soil pressure are discussed.
文摘Introduction Aortic arch anomalies are congenital malformations of the position or branching of the aortic arch,or both.Double aortic arch(DAA)is a very rare malformation,affecting approximately 0.005%~0.007% of fetuses[1],and there has been no relevant literature mentioning the prenatal finding DAA in Macao till now.
基金the financial support of the National Natural Science Foundation of China(No.52075309)the Youth Innovation Team of Shaanxi Universities(21JP021)。
文摘Hydrogel has developed into a very important platform in solar interface evaporator.However,the current hydrogel evaporators are usually three-dimensional evaporators,which will consume a lot of raw materials.Thus,a new two-dimensional hydrogel evaporator is urgently needed to alleviate this problem.Here,a double layer hydrogel evaporator was designed by twice vacuum filtration.Furthermore,through the arched design and the introduction of concentrated brine drainage system,the hydrogel evaporator has enhanced water transportation and tailored water transportation path.Such a unique drainage evaporation system greatly improves the stability of the evaporator.Thereby,a good balance is established between photothermal conversion and water supply,and solar energy is utilized efficiently.It can remain stable in continuous evaporation for up to 12 h with an excellent evaporation rate of 2.70 kg m^(-2)h^(-1)under 1 sun irradiation.Meanwhile,the drainage system realized the 1.8×10^(-10)mol m^(-2)s^(-1)diffusion flux of concentrated brine.Through one-time freeze-drying preparation,an arch-shaped drainage evaporator was used to prepare an evaporation area of more than 20 cm^(2).With the self-made condensate collecting device in outdoor environment,the fresh water yield reaches 7.5 L m^(-2)d^(-1).This provides a new scheme for building a new hydrogel evaporator and solving the fresh water crisis.
