Potash deposits commonly accumulate in highly restricted settings at the final stage of brine evaporation. This does not mean that potash deposits are formed simply as a result of the evaporation concentration of seaw...Potash deposits commonly accumulate in highly restricted settings at the final stage of brine evaporation. This does not mean that potash deposits are formed simply as a result of the evaporation concentration of seawater or lake water, but rather as a coupling result of particular provenance, tectonics and climate activities. In this paper, we focus on the formative mechanism of the potash deposits of Lop Nur depression in Tarim Basin to interpret the detailed coupling mechanism among provenance, tectonics and climate. In terms of the provenance of Lop Nur Lake, the water of the Tarim River which displays ＂potassium-rich＂ characteristics play an important role. In addition, the Pliocene and Lower-Middle Pleistocene clastic beds surrounding Lop Nur Lake host a certain amount of soluble potassium and thus serves as ＂source beds＂ for potash formation. During the late Pliocene, the Lop Nur region has declined and evolved into a great lake from the previous piedmont and diluvial fan area. Since the mid Pleistocene, the great-united Lop Nur Lake has been separated and has generated a chain system consisting of Taitema Lake, Big Ear Lake and Luobei Lake which has turned into the deepest sag in Lop Nur Lake. Dry climate in Lop Nur region has increased since the Pliocene, and became extreme at the late Pleistocene. The study implies that potash formation in Lop Nur Lake depends on the optimal combination of extreme components of provenance, tectonics and climate during a shorter-term period. The optimal patterns of three factors are generally characterized by the long-term accumulation and preliminary enrichment of potassium, the occurrence of the deepest sub-depression and the appearance of an extremely arid climate in Lop Nur region. These factors have been interacting synergistically since the forming of the saline lake and in the later stages strong ＂vapor extraction＂ caused by extremely arid climate is needed to trigger large scale mineralization of potash deposits.展开更多
The main objective of this paper is to investigate and analyse the thermo-hydro-mechanical（THM） coupling phenomena and their influences on the repository safety.In this paper,the high-level waste（HLW） disposal con...The main objective of this paper is to investigate and analyse the thermo-hydro-mechanical（THM） coupling phenomena and their influences on the repository safety.In this paper,the high-level waste（HLW） disposal concept in drifts in clay formation with backfilled bentonite buffer is represented numerically using the CODE BRIGHT developed by the Technical University of Catalonia in Barcelona.The parameters of clay and bentonite used in the simulation are determined by laboratory and in situ experiments.The calculation results are presented to show the hydro-mechanical（HM） processes during the operation phase and the THM processes in the after-closure phase.According to the simulation results,the most probable critical processes for the disposal project have been represented and analyzed.The work also provides an input for additional development regarding the design,assessment and validation of the HLW disposal concept.展开更多
Rail corrugation poses a significant threat to train running safety in the field of railway engineering.Therefore,this study employs numerical analysis to investigate the evolution and formation mechanism of rail corr...Rail corrugation poses a significant threat to train running safety in the field of railway engineering.Therefore,this study employs numerical analysis to investigate the evolution and formation mechanism of rail corrugation in high-speed railways(HSR).Firstly,a three-dimensional(3D)vehicle-track coupled dynamics(VTCD)model is established,which considers the longitudinal wheel-rail(WR)coupling relationship more adequately.Then,by integrating the USFD wear model into this 3D VTCD model,a long-term iterative wear model is developed to reproduce the corrugation evolution process.The predicted corrugation exhibits two distinct wavelength components and closely matches the sample obtained from China's HSR,validating the established model in terms of reliability.Furthermore,the formation mechanism of these two wavelength components is investigated by analyzing the harmonic behavior of vehicle-track coupled systems(VTCS)and the evolution law of rail corrugation under different calculation conditions.The findings reveal that the 3rd-order vertical rail local bending mode(RLBM)between two wheelsets of a bogie(TW-B)is the primary factor contributing to the formation of the long-wavelength component of rail corrugation.The discrete supports of the fasteners do not affect the 3rd-order vertical RLBM,which can be stably excited.Moreover,the vertical rail vibration has a substantial coupled effect on the longitudinal WR creep.When the 3rd-order vertical RLBM is excited,the coupled effect and the negative longitudinal WR creepage together evidently promote the formation of the short-wavelength component of rail corrugation.展开更多
This paper presents a method of establishing a hydrothermal ore-forming reaction system. On the basis of the study of four typical hydrothermal deposits, the folowing conclusions concerning geochemical dynamic control...This paper presents a method of establishing a hydrothermal ore-forming reaction system. On the basis of the study of four typical hydrothermal deposits, the folowing conclusions concerning geochemical dynamic controlling during hydrothermal mineralization have been drawn: (1 ) The regional tectonic activities control the concentration and dispersion of elements in the ore-forming process in terms of their effects on the thermodynamic nature and conditions of the ore-forming reaction system. (2) During hydrothermal mineralization the activities of ore-bearing faults can be divided into two stages: the brittle splitting stage and the brirtle-tough tensing stage, which would create characteristically different geodynamic conditions for the geochemical thermodynamic ore-forming system. (3) The hydrothermal ore-forming reaction system is an open dynamic system. At the brittle splitting stage the system was so strongly supersaturated and unequilibrated as to speed up and enhance the crystallization and differentiation of ore-forming fluids. And at the brittle-tough tensing stage, the ore-forming system was in a weak supersaturated state; with decreasing temperature and pressure the crystallization of oreforming material would slow down, and it can be regarded as an equilibrated state. (4) In the later stages of hydrothermal evolution, gold would be concentrated in the residual ore-forming solution. The pulsating fracture activity in this stage led to the crush of pyrite ore and it was then filled with gold-enriched solution, forming high-grade "fissure" gold ore. This ore-forming process could be called the coupling mechanism of ore formation.展开更多
基金funded by the National Basic Research Program of China(No.2011CB403007)the State Key Program of National Natural Science of China(No.40830420)
文摘Potash deposits commonly accumulate in highly restricted settings at the final stage of brine evaporation. This does not mean that potash deposits are formed simply as a result of the evaporation concentration of seawater or lake water, but rather as a coupling result of particular provenance, tectonics and climate activities. In this paper, we focus on the formative mechanism of the potash deposits of Lop Nur depression in Tarim Basin to interpret the detailed coupling mechanism among provenance, tectonics and climate. In terms of the provenance of Lop Nur Lake, the water of the Tarim River which displays ＂potassium-rich＂ characteristics play an important role. In addition, the Pliocene and Lower-Middle Pleistocene clastic beds surrounding Lop Nur Lake host a certain amount of soluble potassium and thus serves as ＂source beds＂ for potash formation. During the late Pliocene, the Lop Nur region has declined and evolved into a great lake from the previous piedmont and diluvial fan area. Since the mid Pleistocene, the great-united Lop Nur Lake has been separated and has generated a chain system consisting of Taitema Lake, Big Ear Lake and Luobei Lake which has turned into the deepest sag in Lop Nur Lake. Dry climate in Lop Nur region has increased since the Pliocene, and became extreme at the late Pleistocene. The study implies that potash formation in Lop Nur Lake depends on the optimal combination of extreme components of provenance, tectonics and climate during a shorter-term period. The optimal patterns of three factors are generally characterized by the long-term accumulation and preliminary enrichment of potassium, the occurrence of the deepest sub-depression and the appearance of an extremely arid climate in Lop Nur region. These factors have been interacting synergistically since the forming of the saline lake and in the later stages strong ＂vapor extraction＂ caused by extremely arid climate is needed to trigger large scale mineralization of potash deposits.
基金financed and supported by the German research institute "Gesellschaft für Anlagen-und Reaktorsicherheit (GRS) mbH"
文摘The main objective of this paper is to investigate and analyse the thermo-hydro-mechanical（THM） coupling phenomena and their influences on the repository safety.In this paper,the high-level waste（HLW） disposal concept in drifts in clay formation with backfilled bentonite buffer is represented numerically using the CODE BRIGHT developed by the Technical University of Catalonia in Barcelona.The parameters of clay and bentonite used in the simulation are determined by laboratory and in situ experiments.The calculation results are presented to show the hydro-mechanical（HM） processes during the operation phase and the THM processes in the after-closure phase.According to the simulation results,the most probable critical processes for the disposal project have been represented and analyzed.The work also provides an input for additional development regarding the design,assessment and validation of the HLW disposal concept.
基金supported by the National Natural Science Foundation of China(Grant Nos.52222217 and 52388102)the National Key R&D Program of China(Grant No.2023YFB2604301)the Fund from State Key Laboratory of Rail Transit Vehicle System(Grant No.2023TPL-T02)。
文摘Rail corrugation poses a significant threat to train running safety in the field of railway engineering.Therefore,this study employs numerical analysis to investigate the evolution and formation mechanism of rail corrugation in high-speed railways(HSR).Firstly,a three-dimensional(3D)vehicle-track coupled dynamics(VTCD)model is established,which considers the longitudinal wheel-rail(WR)coupling relationship more adequately.Then,by integrating the USFD wear model into this 3D VTCD model,a long-term iterative wear model is developed to reproduce the corrugation evolution process.The predicted corrugation exhibits two distinct wavelength components and closely matches the sample obtained from China's HSR,validating the established model in terms of reliability.Furthermore,the formation mechanism of these two wavelength components is investigated by analyzing the harmonic behavior of vehicle-track coupled systems(VTCS)and the evolution law of rail corrugation under different calculation conditions.The findings reveal that the 3rd-order vertical rail local bending mode(RLBM)between two wheelsets of a bogie(TW-B)is the primary factor contributing to the formation of the long-wavelength component of rail corrugation.The discrete supports of the fasteners do not affect the 3rd-order vertical RLBM,which can be stably excited.Moreover,the vertical rail vibration has a substantial coupled effect on the longitudinal WR creep.When the 3rd-order vertical RLBM is excited,the coupled effect and the negative longitudinal WR creepage together evidently promote the formation of the short-wavelength component of rail corrugation.
文摘This paper presents a method of establishing a hydrothermal ore-forming reaction system. On the basis of the study of four typical hydrothermal deposits, the folowing conclusions concerning geochemical dynamic controlling during hydrothermal mineralization have been drawn: (1 ) The regional tectonic activities control the concentration and dispersion of elements in the ore-forming process in terms of their effects on the thermodynamic nature and conditions of the ore-forming reaction system. (2) During hydrothermal mineralization the activities of ore-bearing faults can be divided into two stages: the brittle splitting stage and the brirtle-tough tensing stage, which would create characteristically different geodynamic conditions for the geochemical thermodynamic ore-forming system. (3) The hydrothermal ore-forming reaction system is an open dynamic system. At the brittle splitting stage the system was so strongly supersaturated and unequilibrated as to speed up and enhance the crystallization and differentiation of ore-forming fluids. And at the brittle-tough tensing stage, the ore-forming system was in a weak supersaturated state; with decreasing temperature and pressure the crystallization of oreforming material would slow down, and it can be regarded as an equilibrated state. (4) In the later stages of hydrothermal evolution, gold would be concentrated in the residual ore-forming solution. The pulsating fracture activity in this stage led to the crush of pyrite ore and it was then filled with gold-enriched solution, forming high-grade "fissure" gold ore. This ore-forming process could be called the coupling mechanism of ore formation.
