Analysis of the in situ stress orientation and magnitude in the No.4 Structure of Nanpu Sag was performed on the basis of data obtained from borehole breakout and acoustic emission measurements.On the basis of mechani...Analysis of the in situ stress orientation and magnitude in the No.4 Structure of Nanpu Sag was performed on the basis of data obtained from borehole breakout and acoustic emission measurements.On the basis of mechanical experiments,logging interpretation,and seismic data,a 3 D geological model and heterogeneous rock mechanics field of the reservoir were constructed.Finite element simulation techniques were then used for the detailed prediction of the 3 D stress field.The results indicated that the maximum horizontal stress orientation in the study area was generally NEE-SWW trending,with significant changes in the in situ stress orientation within and between fault blocks.Along surfaces and profiles,stress magnitudes were discrete and the in situ stress belonged to theⅠa-type.Observed inter-strata differences were characterized as five different types of in situ stress profile.Faults were the most important factor causing large distributional differences in the stress field of reservoirs within the complex fault blocks.The next important influence on the stress field was the reservoir’s rock mechanics parameters,which impacted on the magnitudes of in situ stress magnitudes.This technique provided a theoretical basis for more efficient exploration and development of low-permeability reservoirs within complex fault blocks.展开更多
Magnetic interaction between magnetic particles is of great significance in the fields of magnetic separation and functional materials.A good understanding of interaction mechanism of magnetic particles would further ...Magnetic interaction between magnetic particles is of great significance in the fields of magnetic separation and functional materials.A good understanding of interaction mechanism of magnetic particles would further boost its promising industrial applications.We hereby present our work which visualizes the movement behavior of magnetic spheres in magnetic fields employing high-speed imaging and simulates the dynamic behavior of spheres using an Arbitrary Lagrangian-Eulerian(ALE)based on finite element method.In this paper,we investigated the stress tensor,magnetic force,and dynamic behavior of magnetic spheres in magnetic fields,especially magnetic energy density in different domains.Results show that there are four relatively independent regions of magnetic energy density distribution in external spatial domains of a single sphere system.Attractive force will generate when the energy density in the spatial region between two spheres is relatively high,while a repulsive force will generate when the energy density in the spatial region between two spheres is relatively low.Every magnetic sphere spontaneously moves towards the region with high energy density and stays away from the region with low energy density.The total magnetic energy in magnetic spheres’domains(V_(1))and external spatial domains(V_(2))increases,but the magnetic energy in the external spatial domain decreases over time during the aggregation process.The magnetic spheres ultimately arrange in chain-like structures oriented along magnetic field direction.We hereby proposed a novel and efficient approach to predict the movement trends and final state of magnetic particle swarm from the view of energy density.展开更多
This study presents an example illustrating the role of in situ 3D stress path method in simulating the roof damage development observed in the Mine-by tunnel at Underground Research Laboratory(URL)located in Manitoba...This study presents an example illustrating the role of in situ 3D stress path method in simulating the roof damage development observed in the Mine-by tunnel at Underground Research Laboratory(URL)located in Manitoba,Canada.The 3D stress path,at the point 1 cm in the crown of the Mine-by tunnel,was applied to a cubic Lac du Bonnet(LdB)granite sample to further understand the roof damage process and the associated seismicity.After careful calibrations,a numerical model was used to reproduce the experiment,which produced similar seismicity processes and source mechanisms.Acoustic emission(AE)events obtained from laboratory and numerical modeling were converted to locations in relation to the tunnel face and were compared to the feld microseismicity(MS)occurring in the upper notch region of the Mine-by tunnel.The crack development and damage mechanism are carefully illustrated.The diference between tests and feld monitoring was discussed.The intermediate principal stress(σ_(2))unloading process was carried out in numerical simulation to investigate its role in rock damage development.The results clearly showedσ_(2)could play a signifcant role both in damage development and failure mode.It should be considered when predicting the damage region in underground excavations.This study highlights the potential role of laboratory and numerical stress path tests to investigate fracture processes and mechanisms occurring during engineering activities such as tunnel excavation.展开更多
基金financially supported by the National Oil and Gas Major Project(2016ZX05047-003,2016ZX05014002-006)the National Natural Science Foundation of China(41572124)the Fundamental Research Funds for the Central Universities(17CX05010)
文摘Analysis of the in situ stress orientation and magnitude in the No.4 Structure of Nanpu Sag was performed on the basis of data obtained from borehole breakout and acoustic emission measurements.On the basis of mechanical experiments,logging interpretation,and seismic data,a 3 D geological model and heterogeneous rock mechanics field of the reservoir were constructed.Finite element simulation techniques were then used for the detailed prediction of the 3 D stress field.The results indicated that the maximum horizontal stress orientation in the study area was generally NEE-SWW trending,with significant changes in the in situ stress orientation within and between fault blocks.Along surfaces and profiles,stress magnitudes were discrete and the in situ stress belonged to theⅠa-type.Observed inter-strata differences were characterized as five different types of in situ stress profile.Faults were the most important factor causing large distributional differences in the stress field of reservoirs within the complex fault blocks.The next important influence on the stress field was the reservoir’s rock mechanics parameters,which impacted on the magnitudes of in situ stress magnitudes.This technique provided a theoretical basis for more efficient exploration and development of low-permeability reservoirs within complex fault blocks.
基金supported by National Natural Science Foundation of China (Nos. 5217040329 and 51674091)Natural Science Foundation of Fujian Province (No. 2021J01640)the Open Foundation of the State Key Laboratory of Mineral Processing (Nos. BGRIMM-KJSKL-2021-02 and BGRIMM-KJSKL2022-03)。
文摘Magnetic interaction between magnetic particles is of great significance in the fields of magnetic separation and functional materials.A good understanding of interaction mechanism of magnetic particles would further boost its promising industrial applications.We hereby present our work which visualizes the movement behavior of magnetic spheres in magnetic fields employing high-speed imaging and simulates the dynamic behavior of spheres using an Arbitrary Lagrangian-Eulerian(ALE)based on finite element method.In this paper,we investigated the stress tensor,magnetic force,and dynamic behavior of magnetic spheres in magnetic fields,especially magnetic energy density in different domains.Results show that there are four relatively independent regions of magnetic energy density distribution in external spatial domains of a single sphere system.Attractive force will generate when the energy density in the spatial region between two spheres is relatively high,while a repulsive force will generate when the energy density in the spatial region between two spheres is relatively low.Every magnetic sphere spontaneously moves towards the region with high energy density and stays away from the region with low energy density.The total magnetic energy in magnetic spheres’domains(V_(1))and external spatial domains(V_(2))increases,but the magnetic energy in the external spatial domain decreases over time during the aggregation process.The magnetic spheres ultimately arrange in chain-like structures oriented along magnetic field direction.We hereby proposed a novel and efficient approach to predict the movement trends and final state of magnetic particle swarm from the view of energy density.
基金support for this study is provided by the open fund of State Key Laboratory of Coal Mine Disaster Dynamics and Control(2011DA105287-FW201901)the National Natural Science Foundation of China(51704278)。
文摘This study presents an example illustrating the role of in situ 3D stress path method in simulating the roof damage development observed in the Mine-by tunnel at Underground Research Laboratory(URL)located in Manitoba,Canada.The 3D stress path,at the point 1 cm in the crown of the Mine-by tunnel,was applied to a cubic Lac du Bonnet(LdB)granite sample to further understand the roof damage process and the associated seismicity.After careful calibrations,a numerical model was used to reproduce the experiment,which produced similar seismicity processes and source mechanisms.Acoustic emission(AE)events obtained from laboratory and numerical modeling were converted to locations in relation to the tunnel face and were compared to the feld microseismicity(MS)occurring in the upper notch region of the Mine-by tunnel.The crack development and damage mechanism are carefully illustrated.The diference between tests and feld monitoring was discussed.The intermediate principal stress(σ_(2))unloading process was carried out in numerical simulation to investigate its role in rock damage development.The results clearly showedσ_(2)could play a signifcant role both in damage development and failure mode.It should be considered when predicting the damage region in underground excavations.This study highlights the potential role of laboratory and numerical stress path tests to investigate fracture processes and mechanisms occurring during engineering activities such as tunnel excavation.
