This study aims to reveal the mechanism that how the content of steel fibers and strength grades affect the macro performance of the ultra-high performance fiber reinforced cementitious composite （UHPFRCC） and to st...This study aims to reveal the mechanism that how the content of steel fibers and strength grades affect the macro performance of the ultra-high performance fiber reinforced cementitious composite （UHPFRCC） and to study the UHPFRCC durability under the combined effect of loads and environments. Three types of high and ultra-high performance fiber reinforced cement composites with different strength grades （100, 150, 200 MPa） and different steel fiber volume fractions （0%, 1%, 2%, 3%） are prepared. The main properties of mechanical performance and short-term durability are studied. A preloading frame is designed to apply a four- point load external flexural stress with a stress selection ratio of 0.5 for UHPFRCC150 specimens. The results show that the growth in strength grade with a proper content of steel fiber greatly increases the strength and toughness of the HPFRCC and the UHPFRCC while decreasing the dry-shrinkage ratio. For the loaded specimens, the existence of steel fiber can reduce the negative influence of tensile stress on the Cl- penetration resistance of the UHPFRCC in addition to improving its ability to resist the freeze-thaw damage.展开更多
Mineralisation is the result of the coupled multi-geodynamic processes in the crust. The coupled mechano-thermo-hydrological （MTH） processes are the basic physical processes that govern the location of the hydrother...Mineralisation is the result of the coupled multi-geodynamic processes in the crust. The coupled mechano-thermo-hydrological （MTH） processes are the basic physical processes that govern the location of the hydrothermal mineralization, which can be simulated in the computer by using of the numerical codes, such as FLAC. The numerical modeling results can be used not only to explain the features of existing ore deposits, but also to predict the fhvorable mineralization locations. This paper has summarized the basic equations describing coupled MHT processes in the water-saturated porous rocks, the principles of FLAC, and its application to the MHT processes related to copper mineralization in the Fenghuangshan ore field. We used the FLAC to simulate the syn-deformation cooling and fluid flowing evolution after the intrusion was emplaced and solidified. The modeling results suggest a most prospective exploration area where the subsequent exploration supported the prediction and the test bore hole disclosed the high quality copper ore bodies in the target, demonstrating a positive role of the numerical MTH modeling in facilitating predictive ore discovery.展开更多
Based on a membrane-bulk coupling cell model proposed by Gomez-Marin et al. [ Phys. Rev. Lett. 98 （2007） 168303], the cooperative effects of noise and coupling on the stochastic dynamical behavior are investigated. ...Based on a membrane-bulk coupling cell model proposed by Gomez-Marin et al. [ Phys. Rev. Lett. 98 （2007） 168303], the cooperative effects of noise and coupling on the stochastic dynamical behavior are investigated. For parameters in a certain region, the oscillation can be induced by the cooperative effect of noise and coupling. Whether considering the coupling or not, corresponding coherence resonance phenomena are observed. Furthermore, the effects of two coupling parameters, cell size L and coupling intensity k, on the noise-induced oscillation of membranes are studied. Contrary effects of noise are found in and out of the deterministic oscillatory regions.展开更多
The dynamic tire force of heavy vehicle is a primary reason for road damage. This paper presents a mathematic model to restore the interacting process of vehicle-tire-road system and tries to find out the mechanics of...The dynamic tire force of heavy vehicle is a primary reason for road damage. This paper presents a mathematic model to restore the interacting process of vehicle-tire-road system and tries to find out the mechanics of interaction. A nonlinear tri-axle vehicle model with IBS (integral balanced suspension) is firstly proposed based on the detailed analysis of structural features of a heavy vehicle (DFL1250). The results indicate that the nonlinearities in the vehicle suspension contribute to improvement of ride comfort and to the reduction of dynamic tire force. Furthermore, an FRC (flexible rolling contact) tire model with the enveloping characteristics is added into the IBS model. The tire model considers both the tire contact history with rough road profile and the uneven distribution characteristics of vertical load. The FRC model is able to remove medium and high vibration components from uneven road profile due to its filtering feature. It is expected that these results could supply a new idea for vehicle-road interaction research.展开更多
基金The Technical Research Program from NV Bekaert SA of Belgium (No. 8612000003)the National Natural Science Foundation of China (No. 50908047)
文摘This study aims to reveal the mechanism that how the content of steel fibers and strength grades affect the macro performance of the ultra-high performance fiber reinforced cementitious composite （UHPFRCC） and to study the UHPFRCC durability under the combined effect of loads and environments. Three types of high and ultra-high performance fiber reinforced cement composites with different strength grades （100, 150, 200 MPa） and different steel fiber volume fractions （0%, 1%, 2%, 3%） are prepared. The main properties of mechanical performance and short-term durability are studied. A preloading frame is designed to apply a four- point load external flexural stress with a stress selection ratio of 0.5 for UHPFRCC150 specimens. The results show that the growth in strength grade with a proper content of steel fiber greatly increases the strength and toughness of the HPFRCC and the UHPFRCC while decreasing the dry-shrinkage ratio. For the loaded specimens, the existence of steel fiber can reduce the negative influence of tensile stress on the Cl- penetration resistance of the UHPFRCC in addition to improving its ability to resist the freeze-thaw damage.
文摘Mineralisation is the result of the coupled multi-geodynamic processes in the crust. The coupled mechano-thermo-hydrological （MTH） processes are the basic physical processes that govern the location of the hydrothermal mineralization, which can be simulated in the computer by using of the numerical codes, such as FLAC. The numerical modeling results can be used not only to explain the features of existing ore deposits, but also to predict the fhvorable mineralization locations. This paper has summarized the basic equations describing coupled MHT processes in the water-saturated porous rocks, the principles of FLAC, and its application to the MHT processes related to copper mineralization in the Fenghuangshan ore field. We used the FLAC to simulate the syn-deformation cooling and fluid flowing evolution after the intrusion was emplaced and solidified. The modeling results suggest a most prospective exploration area where the subsequent exploration supported the prediction and the test bore hole disclosed the high quality copper ore bodies in the target, demonstrating a positive role of the numerical MTH modeling in facilitating predictive ore discovery.
基金supported by the National Natural Science Foundation of China under Grant No.10575041
文摘Based on a membrane-bulk coupling cell model proposed by Gomez-Marin et al. [ Phys. Rev. Lett. 98 （2007） 168303], the cooperative effects of noise and coupling on the stochastic dynamical behavior are investigated. For parameters in a certain region, the oscillation can be induced by the cooperative effect of noise and coupling. Whether considering the coupling or not, corresponding coherence resonance phenomena are observed. Furthermore, the effects of two coupling parameters, cell size L and coupling intensity k, on the noise-induced oscillation of membranes are studied. Contrary effects of noise are found in and out of the deterministic oscillatory regions.
基金supported by the NSFC Key Program (Grant No. 10932006)Key Project of Chinese Ministry of Education (Grant No. 210023)the National Natural Science Foundation of China (Grant No. 11072159)
文摘The dynamic tire force of heavy vehicle is a primary reason for road damage. This paper presents a mathematic model to restore the interacting process of vehicle-tire-road system and tries to find out the mechanics of interaction. A nonlinear tri-axle vehicle model with IBS (integral balanced suspension) is firstly proposed based on the detailed analysis of structural features of a heavy vehicle (DFL1250). The results indicate that the nonlinearities in the vehicle suspension contribute to improvement of ride comfort and to the reduction of dynamic tire force. Furthermore, an FRC (flexible rolling contact) tire model with the enveloping characteristics is added into the IBS model. The tire model considers both the tire contact history with rough road profile and the uneven distribution characteristics of vertical load. The FRC model is able to remove medium and high vibration components from uneven road profile due to its filtering feature. It is expected that these results could supply a new idea for vehicle-road interaction research.
