The characteristics of high-filled embankment rheological settlement were analyzed;mechanical calculation model of high-filled embankment rheological settlement during constructing and running period was also put forw...The characteristics of high-filled embankment rheological settlement were analyzed;mechanical calculation model of high-filled embankment rheological settlement during constructing and running period was also put forward.Combining the macroscopic and microscopic deformation properties of the engineering soil grain,its constitutive model was set up and its characters were fully revealed,at the same time,its practical calculation formula under the action of dead-weight load was derived,which is feasible by analysis and comparison.展开更多
Foundation settlement is of great significance for high-fill engineering in collapsible loess areas.To predict the construction settlement of Lüliang Airport located in Shanxi Province,China,a plane strain finite...Foundation settlement is of great significance for high-fill engineering in collapsible loess areas.To predict the construction settlement of Lüliang Airport located in Shanxi Province,China,a plane strain finite element method considering the linear variation in the modulus,was carried out in this paper based on the results of geotechnical tests.The stress and deformation of four typical sections caused by layered fill are simulated,and then the settlement of the high-fill airport is calculated and analyzed by inputting three sets of parameters.The relative soft parameters of loess geomaterials produce more settlement than the relatively hard parameters.The thicker the filling body is,the greater the settlement is.The filling body constrained by mountains on both sides produces less settlement than the filling body constrained by a mountain on only one side even the filling thickness is almost the same.The settlement caused by the original subbase accounts for 56%−77%of the total settlement,while the fill soils themselves accounts for 23%−44%of the total settlement,which is approximately consistent with the field monitoring results.It provides a good reference for predicting the settlement of similar high-fill engineering.展开更多
The exact radar cross-section （RCS） measurement is difficult when the scattering of targets is low. Ful polarimetric cali-bration is one technique that offers the potential for improving the accuracy of RCS measurem...The exact radar cross-section （RCS） measurement is difficult when the scattering of targets is low. Ful polarimetric cali-bration is one technique that offers the potential for improving the accuracy of RCS measurements. There are numerous polarimetric calibration algorithms. Some complex expressions in these algo-rithms cannot be easily used in an engineering practice. A radar polarimetric coefficients matrix （RPCM） with a simpler expression is presented for the monostatic radar polarization scattering matrix （PSM） measurement. Using a rhombic dihedral corner reflector and a metal ic sphere, the RPCM can be obtained by solving a set of equations, which can be used to find the true PSM for any target. An example for the PSM of a metal ic dish shows that the proposed method obviously improves the accuracy of cross-polarized RCS measurements.展开更多
Based on the vehicle track coupling dynamics theory, a new spatial dynamic numerical model of vehicle track subgrade coupling system was established considering the interaction among different structural layers in the...Based on the vehicle track coupling dynamics theory, a new spatial dynamic numerical model of vehicle track subgrade coupling system was established considering the interaction among different structural layers in the subgrade system. The dynamic responses of the coupled system were analyzed when the speed of train was 350 km/h and the transition was filled with graded broken stones mixed with 5% cement. The results indicate that the setting form of bridge-approach embankment section has little effect on the dynamic responses, thus designers can choose it on account of the practical circumstances. Because the location about 5 m from the bridge abutment has the greatest deformation, the stiffness within 0 5 m zone behind the abutment should be specially designed. The results of the study from vehicle track dynamics show that the maximum allowable track deflection angle should be 0.09% and the coefficient of subgrade reaction(K30) is greater than 190 MPa within the 0 5 m zone behind the abutment and greater than 150 MPa in other zones.展开更多
The Qaidam Basin,located in the northern margin of the Qinghai-Tibet Plateau,is a large Mesozoic -Cenozoic basin,and bears huge thick Cenozoic strata.The geologic events of the Indian-Eurasian plate-plate collision si...The Qaidam Basin,located in the northern margin of the Qinghai-Tibet Plateau,is a large Mesozoic -Cenozoic basin,and bears huge thick Cenozoic strata.The geologic events of the Indian-Eurasian plate-plate collision since～55 Ma have been well recorded.Based on the latest progress in high-resolution stratigraphy,a technique of balanced section was applied to six pieces of northeast-southwest geologic seismic profiles in the central and eastern of the Qaidam Basin to reconstruct the crustal shortening deformation history during the Cenozoic collision. The results show that the Qaidam Basin began展开更多
With the increasing traffic demand, the closely built three or more tunnels with large section play a significant role in the tunnel construction. However, the interaction among tunnels has important influences on the...With the increasing traffic demand, the closely built three or more tunnels with large section play a significant role in the tunnel construction. However, the interaction among tunnels has important influences on the security and economy of tunnel engineering, and the calculation of pressure from the surrounding rock during the excavation is one of the problems that need to be solved urgently. Based on the practical engineering of three tunnels, the load model of three tunnels was proposed in consideration of the interaction and excavation sequence between tunnels. In comparison with the load model of single tunnel, the construction mechanical characteristics of the three tunnels were analyzed. The results show that the rock pressure of three tunnels calculated by the current tunnel design code is not reliable, and the interaction force increases with the spacing between tunnels.展开更多
The influence of enlarged section parameters on pressure transients of high-speed train passing through a tunnel was investigated by numerical simulation.The calculation results obtained by the structured and unstruct...The influence of enlarged section parameters on pressure transients of high-speed train passing through a tunnel was investigated by numerical simulation.The calculation results obtained by the structured and unstructured grid and the experimental results of smooth wall tunnel were verified.Numerical simulation studies were conducted on three tunnel enlarged section parameters,the enlarged section distribution along circumferential direction,the enlarged section area and the enlarged section distribution along tunnel length direction.The calculation results show that the influence of the different enlarged section distributions along tunnel circumferential direction on pressure transients in the tunnel is basically consistent.There is an optimal enlarged section area for the minimum value of the pressure variation amplitude and the average pressure variation in the tunnel.The law of the pressure variation amplitude and the average pressure variation of the enlarged section distribution along tunnel length direction are obtained.展开更多
A number of geological cross\|sections from the western Himalayan foothills are based on field,seismic reflection,and well data of the Oil & Natural Gas Corporation India.These cross\|sections have been described ...A number of geological cross\|sections from the western Himalayan foothills are based on field,seismic reflection,and well data of the Oil & Natural Gas Corporation India.These cross\|sections have been described by two contradictory interpretations.The first interpretation that depicts a prominent basal decollement above the pre\|Tertiary sequence is used for palinspastic reconstruction,using line length balancing,and determination of total shortening in the area.The second interpretation reveals a large variation in the thickness of individual stratigraphic horizons and a number of flower structures.These flower structures never cut the Himalayan thrusts but terminate below them.Away from the thrusts,the faults cut the younger Siwalik molasse (Middle Miocene—Pleistocene)and even reach to the surface as strike slip faults.Apart from the presence of strike slip faults,the other constraints for restoration of the section is oblique ramp structure at the Kangra Reentrant (or Punjab Reentrant).The oblique ramp was formed as a normal fault during the tensional regime in the region and later reactivated as thrust fault during the Tertiary Himalayan orogeny.These features reveal that the assumption of plane strain deformation is not valid for the region.Furthermore,the amount of extension during pre\|Tertiary rifting and layer parallel shortening during the Tertiary compressional phase is still unknown hence balancing of the sections is problematic.展开更多
Geological studies indicate that Qinghai\|Tibet plateau crust has shortened at least 2500km and the thickness was increased to 60～70km in the past 45Ma. Different researchers advocate different views to explain the s...Geological studies indicate that Qinghai\|Tibet plateau crust has shortened at least 2500km and the thickness was increased to 60～70km in the past 45Ma. Different researchers advocate different views to explain the shortening according to their studies.( Tapponnier,1977;Chang et al,1986;England et al,1986;Murphy,1997;Y.Pan,1999),however it is still unresolved on how much shortening in upper crustal especially in Qiangtang terrain.Qiangtang terrain is located in the center of Qinghai\|Tibet plateau, the tectonic deformation has been resulted from intracontinental convergence and collision of India plate with Eurasian plate.The deformation style of Qiangtang terrain shows east\|west\|trending folds and thrusts which formed in the shallow tectonic level during collisional\|intracontinental period. The folds type is characterized by nonpenetrative\|foliation parallel fold, the hinges have the same trend with the thrusts. These traits are favourable for restoring the balanced cross\|section and measuring the shortening. The balanced reconstruction is based on line balancing on three different stratigraphic sections (A,B and C)across the Northern Qiangtang basin in the area between 85°E and 87°E.The sections are all north\|south\|trending in accordance with the moving direction of thrusts.展开更多
The stability control of surrounding rock for large or super-large section chamber is a difficult technical problem in deep mining condition.Based on the in-site geological conditions of Longgu coal mine,this paper us...The stability control of surrounding rock for large or super-large section chamber is a difficult technical problem in deep mining condition.Based on the in-site geological conditions of Longgu coal mine,this paper used the dynamic module of FLAC3D to study the response characteristics of deep super-large section chamber under dynamic and static combined loading condition.Results showed that under the static loading condition,the maximum vertical stress,deformation and failure range are large,where the stress concentration coefficient is 1.64.The maximum roof-to-floor and two-sides deformations are 54.6 mm and 53.1 mm,respectively.Then,under the dynamic and static combined loading condition:(1)The influence of dynamic load frequency on the two-sides is more obvious;(2)The dynamic load amplitude has the greatest influence on the stress concentration degree,and the plastic failure tends to develop to the deeper;(3)With the dynamic load source distance increase,the response of surrounding rock is gradually attenuated.On this basis,empirical equations for each dynamic load conditions were obtained by using regression analysis method,and all correlation coefficients are greater than 0.99.This research provided reference for the supporting design of deep super-large section chamber under same or similar conditions.展开更多
A new method of calculating the radai cross section (RCS) for wing-body blended targets is presented and verified. The method utilizes a computer program for modeling targets' geometry in terms of small pieces. Th...A new method of calculating the radai cross section (RCS) for wing-body blended targets is presented and verified. The method utilizes a computer program for modeling targets' geometry in terms of small pieces. The calculation is based on physical optics approximation. Examples are given to show the validity of the method.展开更多
During the desing of channel transect,the paper brings forward golden section method,which is 0.618 methods.In order to reduce the calculation volume of the natural depth of water h 0 and bottomˉwidth b which apply ...During the desing of channel transect,the paper brings forward golden section method,which is 0.618 methods.In order to reduce the calculation volume of the natural depth of water h 0 and bottomˉwidth b which apply trial calculation method and graphic method,and improve the calculate precision,the mathematical model has been built up,the writer combines example to explain the train of thought,the result shows that the calculation precision is high,the correctness is tested and verified by the result which is calculated by hand.It can be referred to the hydroelectric works.展开更多
Based on transient temperature field theory of heat conduction, the solar temperature field calculation model of U-shape sectioned high-speed railway cable-stayed bridge under actions of concrete beams and ballast was...Based on transient temperature field theory of heat conduction, the solar temperature field calculation model of U-shape sectioned high-speed railway cable-stayed bridge under actions of concrete beams and ballast was established. Using parametric programming language, finite element calculation modules considering climate conditions, bridge site, structure dimension and material thermophysical properties were compiled. Six standard day cycles with the strongest yearly radiation among the bridge sites were selected for sectional solar temperature field calculation and temperature distributions under different temperature-sensitive parameters were compared. The results show that under the influence of sunshine, U-shape section of the beam shows obvious nonlinear distribution characteristics and the maximum cross-section temperature difference is more than 21℃; the ballast significantly reduces sunshine temperature difference of the beam and temperature peak of the bottom margin lags with the increase of ballast thickness; the maximum cross-section vertical temperature gradient appears in summer while large transverse temperature difference appears in winter.展开更多
Casting-cold extrusion technology was presented to fabricate alttminum/copper clad composite, and copper tubes with different sketch sections were designed. The technology of aluminum/copper clad composite fabricated ...Casting-cold extrusion technology was presented to fabricate alttminum/copper clad composite, and copper tubes with different sketch sections were designed. The technology of aluminum/copper clad composite fabricated by casting-cold extrusion was simulated by DEFORM software using tubes with four arc grooves. The stress and strain in different deformation zones were analyzed. The groove size reduces gradually and the groove shape drives to triangle during the extrusion procedure. The maximum values of equivalent effective stress and radial stress appear in groove zones, and the maximum equivalent effective strain firstly is obtained also in groove zones. The grain size in groove zones is less than that in other zones. The experimental results are consistent with simulation results, which prove that the copper tubes with sketch section are favorable to the metallurgy bond of boundary interface between aluminum and copper.展开更多
基金Project(06C843) supported by the Scientific Research Fund of Hunan Provincial Education Department,China
文摘The characteristics of high-filled embankment rheological settlement were analyzed;mechanical calculation model of high-filled embankment rheological settlement during constructing and running period was also put forward.Combining the macroscopic and microscopic deformation properties of the engineering soil grain,its constitutive model was set up and its characters were fully revealed,at the same time,its practical calculation formula under the action of dead-weight load was derived,which is feasible by analysis and comparison.
基金Project(2020M670604)supported by the China Postdoctoral Science FoundationProject(41790434)supported by the National Natural Science Foundation of China。
文摘Foundation settlement is of great significance for high-fill engineering in collapsible loess areas.To predict the construction settlement of Lüliang Airport located in Shanxi Province,China,a plane strain finite element method considering the linear variation in the modulus,was carried out in this paper based on the results of geotechnical tests.The stress and deformation of four typical sections caused by layered fill are simulated,and then the settlement of the high-fill airport is calculated and analyzed by inputting three sets of parameters.The relative soft parameters of loess geomaterials produce more settlement than the relatively hard parameters.The thicker the filling body is,the greater the settlement is.The filling body constrained by mountains on both sides produces less settlement than the filling body constrained by a mountain on only one side even the filling thickness is almost the same.The settlement caused by the original subbase accounts for 56%−77%of the total settlement,while the fill soils themselves accounts for 23%−44%of the total settlement,which is approximately consistent with the field monitoring results.It provides a good reference for predicting the settlement of similar high-fill engineering.
基金supported by the National Basic Research Program of China(973 Program)(2010CB731905)
文摘The exact radar cross-section （RCS） measurement is difficult when the scattering of targets is low. Ful polarimetric cali-bration is one technique that offers the potential for improving the accuracy of RCS measurements. There are numerous polarimetric calibration algorithms. Some complex expressions in these algo-rithms cannot be easily used in an engineering practice. A radar polarimetric coefficients matrix （RPCM） with a simpler expression is presented for the monostatic radar polarization scattering matrix （PSM） measurement. Using a rhombic dihedral corner reflector and a metal ic sphere, the RPCM can be obtained by solving a set of equations, which can be used to find the true PSM for any target. An example for the PSM of a metal ic dish shows that the proposed method obviously improves the accuracy of cross-polarized RCS measurements.
基金Project(41030742) supported by the National Natural Science Foundation of ChinaProject(2009G010-c) supported by the Technological Research and Development Programs of the Ministry of Railways,China
文摘Based on the vehicle track coupling dynamics theory, a new spatial dynamic numerical model of vehicle track subgrade coupling system was established considering the interaction among different structural layers in the subgrade system. The dynamic responses of the coupled system were analyzed when the speed of train was 350 km/h and the transition was filled with graded broken stones mixed with 5% cement. The results indicate that the setting form of bridge-approach embankment section has little effect on the dynamic responses, thus designers can choose it on account of the practical circumstances. Because the location about 5 m from the bridge abutment has the greatest deformation, the stiffness within 0 5 m zone behind the abutment should be specially designed. The results of the study from vehicle track dynamics show that the maximum allowable track deflection angle should be 0.09% and the coefficient of subgrade reaction(K30) is greater than 190 MPa within the 0 5 m zone behind the abutment and greater than 150 MPa in other zones.
文摘The Qaidam Basin,located in the northern margin of the Qinghai-Tibet Plateau,is a large Mesozoic -Cenozoic basin,and bears huge thick Cenozoic strata.The geologic events of the Indian-Eurasian plate-plate collision since～55 Ma have been well recorded.Based on the latest progress in high-resolution stratigraphy,a technique of balanced section was applied to six pieces of northeast-southwest geologic seismic profiles in the central and eastern of the Qaidam Basin to reconstruct the crustal shortening deformation history during the Cenozoic collision. The results show that the Qaidam Basin began
基金Project(2011CB01380) supported by the National Basic Research Program of ChinaProject(51178468) supported by the National Natural Science Foundation of ChinaProject(2011G013-B) supported by Science and Technology Development of Railways Department in China
文摘With the increasing traffic demand, the closely built three or more tunnels with large section play a significant role in the tunnel construction. However, the interaction among tunnels has important influences on the security and economy of tunnel engineering, and the calculation of pressure from the surrounding rock during the excavation is one of the problems that need to be solved urgently. Based on the practical engineering of three tunnels, the load model of three tunnels was proposed in consideration of the interaction and excavation sequence between tunnels. In comparison with the load model of single tunnel, the construction mechanical characteristics of the three tunnels were analyzed. The results show that the rock pressure of three tunnels calculated by the current tunnel design code is not reliable, and the interaction force increases with the spacing between tunnels.
基金Project (2016YFB1200602-11) supported by National Key R&D Plan of China
文摘The influence of enlarged section parameters on pressure transients of high-speed train passing through a tunnel was investigated by numerical simulation.The calculation results obtained by the structured and unstructured grid and the experimental results of smooth wall tunnel were verified.Numerical simulation studies were conducted on three tunnel enlarged section parameters,the enlarged section distribution along circumferential direction,the enlarged section area and the enlarged section distribution along tunnel length direction.The calculation results show that the influence of the different enlarged section distributions along tunnel circumferential direction on pressure transients in the tunnel is basically consistent.There is an optimal enlarged section area for the minimum value of the pressure variation amplitude and the average pressure variation in the tunnel.The law of the pressure variation amplitude and the average pressure variation of the enlarged section distribution along tunnel length direction are obtained.
文摘A number of geological cross\|sections from the western Himalayan foothills are based on field,seismic reflection,and well data of the Oil & Natural Gas Corporation India.These cross\|sections have been described by two contradictory interpretations.The first interpretation that depicts a prominent basal decollement above the pre\|Tertiary sequence is used for palinspastic reconstruction,using line length balancing,and determination of total shortening in the area.The second interpretation reveals a large variation in the thickness of individual stratigraphic horizons and a number of flower structures.These flower structures never cut the Himalayan thrusts but terminate below them.Away from the thrusts,the faults cut the younger Siwalik molasse (Middle Miocene—Pleistocene)and even reach to the surface as strike slip faults.Apart from the presence of strike slip faults,the other constraints for restoration of the section is oblique ramp structure at the Kangra Reentrant (or Punjab Reentrant).The oblique ramp was formed as a normal fault during the tensional regime in the region and later reactivated as thrust fault during the Tertiary Himalayan orogeny.These features reveal that the assumption of plane strain deformation is not valid for the region.Furthermore,the amount of extension during pre\|Tertiary rifting and layer parallel shortening during the Tertiary compressional phase is still unknown hence balancing of the sections is problematic.
文摘Geological studies indicate that Qinghai\|Tibet plateau crust has shortened at least 2500km and the thickness was increased to 60～70km in the past 45Ma. Different researchers advocate different views to explain the shortening according to their studies.( Tapponnier,1977;Chang et al,1986;England et al,1986;Murphy,1997;Y.Pan,1999),however it is still unresolved on how much shortening in upper crustal especially in Qiangtang terrain.Qiangtang terrain is located in the center of Qinghai\|Tibet plateau, the tectonic deformation has been resulted from intracontinental convergence and collision of India plate with Eurasian plate.The deformation style of Qiangtang terrain shows east\|west\|trending folds and thrusts which formed in the shallow tectonic level during collisional\|intracontinental period. The folds type is characterized by nonpenetrative\|foliation parallel fold, the hinges have the same trend with the thrusts. These traits are favourable for restoring the balanced cross\|section and measuring the shortening. The balanced reconstruction is based on line balancing on three different stratigraphic sections (A,B and C)across the Northern Qiangtang basin in the area between 85°E and 87°E.The sections are all north\|south\|trending in accordance with the moving direction of thrusts.
基金Project(2018YFC0604703)supported by the National Key R&D Program of ChinaProjects(51804181,51874190)supported by the National Natural Science Foundation of China+3 种基金Project(ZR2018QEE002)supported by the Shandong Province Natural Science Fund,ChinaProject(ZR2018ZA0603)supported by the Major Program of Shandong Province Natural Science Foundation,ChinaProject(2019GSF116003)supported by the Key R&D Project of Shandong Province,ChinaProject(SDKDYC190234)supported by the Shandong University of Science and Technology,Graduate Student Technology Innovation Project,China。
文摘The stability control of surrounding rock for large or super-large section chamber is a difficult technical problem in deep mining condition.Based on the in-site geological conditions of Longgu coal mine,this paper used the dynamic module of FLAC3D to study the response characteristics of deep super-large section chamber under dynamic and static combined loading condition.Results showed that under the static loading condition,the maximum vertical stress,deformation and failure range are large,where the stress concentration coefficient is 1.64.The maximum roof-to-floor and two-sides deformations are 54.6 mm and 53.1 mm,respectively.Then,under the dynamic and static combined loading condition:(1)The influence of dynamic load frequency on the two-sides is more obvious;(2)The dynamic load amplitude has the greatest influence on the stress concentration degree,and the plastic failure tends to develop to the deeper;(3)With the dynamic load source distance increase,the response of surrounding rock is gradually attenuated.On this basis,empirical equations for each dynamic load conditions were obtained by using regression analysis method,and all correlation coefficients are greater than 0.99.This research provided reference for the supporting design of deep super-large section chamber under same or similar conditions.
文摘A new method of calculating the radai cross section (RCS) for wing-body blended targets is presented and verified. The method utilizes a computer program for modeling targets' geometry in terms of small pieces. The calculation is based on physical optics approximation. Examples are given to show the validity of the method.
文摘During the desing of channel transect,the paper brings forward golden section method,which is 0.618 methods.In order to reduce the calculation volume of the natural depth of water h 0 and bottomˉwidth b which apply trial calculation method and graphic method,and improve the calculate precision,the mathematical model has been built up,the writer combines example to explain the train of thought,the result shows that the calculation precision is high,the correctness is tested and verified by the result which is calculated by hand.It can be referred to the hydroelectric works.
基金Project(51378503)supported by the National Natural Science Foundation of ChinaProject(2010G018-A-3)supported by Technology Research and Development Program of the Ministry of Railways,China
文摘Based on transient temperature field theory of heat conduction, the solar temperature field calculation model of U-shape sectioned high-speed railway cable-stayed bridge under actions of concrete beams and ballast was established. Using parametric programming language, finite element calculation modules considering climate conditions, bridge site, structure dimension and material thermophysical properties were compiled. Six standard day cycles with the strongest yearly radiation among the bridge sites were selected for sectional solar temperature field calculation and temperature distributions under different temperature-sensitive parameters were compared. The results show that under the influence of sunshine, U-shape section of the beam shows obvious nonlinear distribution characteristics and the maximum cross-section temperature difference is more than 21℃; the ballast significantly reduces sunshine temperature difference of the beam and temperature peak of the bottom margin lags with the increase of ballast thickness; the maximum cross-section vertical temperature gradient appears in summer while large transverse temperature difference appears in winter.
文摘Casting-cold extrusion technology was presented to fabricate alttminum/copper clad composite, and copper tubes with different sketch sections were designed. The technology of aluminum/copper clad composite fabricated by casting-cold extrusion was simulated by DEFORM software using tubes with four arc grooves. The stress and strain in different deformation zones were analyzed. The groove size reduces gradually and the groove shape drives to triangle during the extrusion procedure. The maximum values of equivalent effective stress and radial stress appear in groove zones, and the maximum equivalent effective strain firstly is obtained also in groove zones. The grain size in groove zones is less than that in other zones. The experimental results are consistent with simulation results, which prove that the copper tubes with sketch section are favorable to the metallurgy bond of boundary interface between aluminum and copper.
