Given the background of a transmission tower erected on a particular mining subsidence area,we used finite element modeling to analyze the anti-deformation performance of transmission towers under a number of differen...Given the background of a transmission tower erected on a particular mining subsidence area,we used finite element modeling to analyze the anti-deformation performance of transmission towers under a number of different load conditions,including horizontal foundation displacement,uneven vertical downward displacement,wind loads and icing conditions.The results show that the failure in stability of a single steel angle iron represents the limit of the tower given ground deformation.We calculated the corresponding limits of foundation displacements.The results indicate that compression displacement of the foundation is more dangerous than tension displacement.Under complex foundation displacement conditions,horizontal foundation displacement is a key factor leading to failure in the stability of towers.Under conditions of compression or tension displacement of the foundation,wind load becomes the key factor.Towers do not fail when foundation displacements are smaller than 1% (under tension) or 0.5% (under horizontal compression or single foundation subsidence) of the distance between two supports.展开更多
The theoretical relationship between water injection multiple(i.e.injected pore volume)and water saturation is inferred from theoretical concepts of reservoir engineering.A mathematical model based on core displacemen...The theoretical relationship between water injection multiple(i.e.injected pore volume)and water saturation is inferred from theoretical concepts of reservoir engineering.A mathematical model based on core displacement tests is established for the entire injection process that satisfies both initial displacement and extreme displacement,simultaneously.The results show that prior to the flooding,the water injection multiple has a linear relationship with the water saturation,and the utilization rate of the injected water is the highest.As water breakthrough at the production end,the water-cut increases,and the injection multiple increases exponentially while the utilization efficiency of the injected water gradually decreases.When the injection multiple approaches infinity,the utilization efficiency of the injected water gradually decreases to 0,by which time the water-cut at the production end is always 1.At this time,the water saturation no longer changes,and the water flooding recovery rate reaches its limit.Based on the experimental test data,a mathematical model of the entire process of injection multiple and water saturation is established,which has high fitting accuracy that can predict the injection multiple in the different stages of development of a mature oil reservoir.The dynamically changing index of the injection water utilization efficiency in reservoir development by reactive water flooding can be obtained through reasonable transformation of the mathematical model.This is of great significance in guiding evaluations of the effects of reservoir development and formulating countermeasures.展开更多
In the Da Hinggan Mountains,the safe and smooth operation of shallowly buried oil pipelines is threatened greatly by the frozeneheave damage derived from frozen soil.At present,a closed frozeneheave simulation test is...In the Da Hinggan Mountains,the safe and smooth operation of shallowly buried oil pipelines is threatened greatly by the frozeneheave damage derived from frozen soil.At present,a closed frozeneheave simulation test is often carried out in China,with water content and dry density of samples being assumed to be constant.However,an open frozeneheave test,all the factors of which change as the test goes on,can reflect the real frozeneheave damage more accurately.In this paper,the open frozeneheave test was carried out on five types frozen soil along the ChinaeRussia Crude Oil Pipeline to measure the frozeneheave factor and water content of each soil sample and accordingly analyze their relationship.Besides,its test results were compared with that of the closed frozeneheave test.Then,the normal frozeneheave force was measured by using the displacement limiting method,and this measurement was compared with the result of the static equilibrium test.Finally,a difference significance test was conducted.It is shown that the frozeneheave factor of the open test is higher than that of the closed test;the frozeneheave factor of fine grained soil has a significant effect on the frozeneheave factor of soils,and the frozeneheave factor increases as the capillary effect or the swabbing action of soil increases;the frozeneheave factor of coarse grained soil is mainly dependent on the mud content,and it is lower than that of fine grained soil;the value of frozeneheave force is in close relation with the test methods and the sample height;it is indicated that the open frozeneheave test is more applicable to the investigation on the frozeneheave of the foundation soils of pipelines in the Da Hinggan Mountains.It is concluded that the soils for the cushion and digging/packing layers of the pipelines in the permafrost regions shall be acted by the gravel or detritus with lower mud content,and waterproof and draining pipeline jetty shall be made from the clay soils with a higher plasticity.展开更多
Coarse-grained（CG） metals strengthened by nanotwinned（NT） regions possess high strength and good ductility. As such, they are very suitable for applications in bullet-proof targets. Here, a numerical model based o...Coarse-grained（CG） metals strengthened by nanotwinned（NT） regions possess high strength and good ductility. As such, they are very suitable for applications in bullet-proof targets. Here, a numerical model based on the conventional theory of strain gradient plasticity and the Johnson–Cook failure criterion is employed to study the influences of volume fraction of NT regions on their ballistic performance.The results show that in general a relatively small twin spacing（4–10 nm） and a moderate volume fraction（7%–20%） will lead to excellent limit velocity and that the influences of volume fraction on limit displacement change with the category of impact processes.展开更多
基金National Natural Science Foundation of China(No.50004008)Xuzhou Power Supply Company and the Fundamental Research Funds for the Central Universities(No.2011QNB18) for their financial and technical support for this work
文摘Given the background of a transmission tower erected on a particular mining subsidence area,we used finite element modeling to analyze the anti-deformation performance of transmission towers under a number of different load conditions,including horizontal foundation displacement,uneven vertical downward displacement,wind loads and icing conditions.The results show that the failure in stability of a single steel angle iron represents the limit of the tower given ground deformation.We calculated the corresponding limits of foundation displacements.The results indicate that compression displacement of the foundation is more dangerous than tension displacement.Under complex foundation displacement conditions,horizontal foundation displacement is a key factor leading to failure in the stability of towers.Under conditions of compression or tension displacement of the foundation,wind load becomes the key factor.Towers do not fail when foundation displacements are smaller than 1% (under tension) or 0.5% (under horizontal compression or single foundation subsidence) of the distance between two supports.
文摘The theoretical relationship between water injection multiple(i.e.injected pore volume)and water saturation is inferred from theoretical concepts of reservoir engineering.A mathematical model based on core displacement tests is established for the entire injection process that satisfies both initial displacement and extreme displacement,simultaneously.The results show that prior to the flooding,the water injection multiple has a linear relationship with the water saturation,and the utilization rate of the injected water is the highest.As water breakthrough at the production end,the water-cut increases,and the injection multiple increases exponentially while the utilization efficiency of the injected water gradually decreases.When the injection multiple approaches infinity,the utilization efficiency of the injected water gradually decreases to 0,by which time the water-cut at the production end is always 1.At this time,the water saturation no longer changes,and the water flooding recovery rate reaches its limit.Based on the experimental test data,a mathematical model of the entire process of injection multiple and water saturation is established,which has high fitting accuracy that can predict the injection multiple in the different stages of development of a mature oil reservoir.The dynamically changing index of the injection water utilization efficiency in reservoir development by reactive water flooding can be obtained through reasonable transformation of the mathematical model.This is of great significance in guiding evaluations of the effects of reservoir development and formulating countermeasures.
基金Project supported by the National Natural Science Foundation Project“Research on the Frozeneheave Mechanism of Marsh Turfy Soil in Seasonally Frozen Area”(No.41502272)Seed Fund Project of Changchun Institute of Technology,“Research on the FrozeneThaw Cycle Effect of Shallowly Buried Pipelines in the Permafrost Zone of Da Hinggan Mountains”(No.320160017).
文摘In the Da Hinggan Mountains,the safe and smooth operation of shallowly buried oil pipelines is threatened greatly by the frozeneheave damage derived from frozen soil.At present,a closed frozeneheave simulation test is often carried out in China,with water content and dry density of samples being assumed to be constant.However,an open frozeneheave test,all the factors of which change as the test goes on,can reflect the real frozeneheave damage more accurately.In this paper,the open frozeneheave test was carried out on five types frozen soil along the ChinaeRussia Crude Oil Pipeline to measure the frozeneheave factor and water content of each soil sample and accordingly analyze their relationship.Besides,its test results were compared with that of the closed frozeneheave test.Then,the normal frozeneheave force was measured by using the displacement limiting method,and this measurement was compared with the result of the static equilibrium test.Finally,a difference significance test was conducted.It is shown that the frozeneheave factor of the open test is higher than that of the closed test;the frozeneheave factor of fine grained soil has a significant effect on the frozeneheave factor of soils,and the frozeneheave factor increases as the capillary effect or the swabbing action of soil increases;the frozeneheave factor of coarse grained soil is mainly dependent on the mud content,and it is lower than that of fine grained soil;the value of frozeneheave force is in close relation with the test methods and the sample height;it is indicated that the open frozeneheave test is more applicable to the investigation on the frozeneheave of the foundation soils of pipelines in the Da Hinggan Mountains.It is concluded that the soils for the cushion and digging/packing layers of the pipelines in the permafrost regions shall be acted by the gravel or detritus with lower mud content,and waterproof and draining pipeline jetty shall be made from the clay soils with a higher plasticity.
基金supported by the National Natural Science Foundation of China(11372214)the opening project of State Key Laboratory of Explosion Science and Technology(Beijing Institute of Technology)(KFJJ17-10M)+1 种基金the support of the NSF Mechanics of Materials Program under CMMI-1162431the support from the Advanced Engineering Programme and School of Engineering,Monash University Malaysia
文摘Coarse-grained（CG） metals strengthened by nanotwinned（NT） regions possess high strength and good ductility. As such, they are very suitable for applications in bullet-proof targets. Here, a numerical model based on the conventional theory of strain gradient plasticity and the Johnson–Cook failure criterion is employed to study the influences of volume fraction of NT regions on their ballistic performance.The results show that in general a relatively small twin spacing（4–10 nm） and a moderate volume fraction（7%–20%） will lead to excellent limit velocity and that the influences of volume fraction on limit displacement change with the category of impact processes.
