There is a pressing need for high-performance,high-strength low-alloy structural(HSLA)steels in various engineering fields,such as hydraulic components,engineering machinery,bridges,ships,and pressure vessels.In this ...There is a pressing need for high-performance,high-strength low-alloy structural(HSLA)steels in various engineering fields,such as hydraulic components,engineering machinery,bridges,ships,and pressure vessels.In this study,a gradient dislocation-cell structure is introduced into an HSLA steel through ultrasonic severe surface rolling.The cell size is approximately 614 nm at the topmost surface layer,and increases with increasing the depth.Most of the cell walls have a misorientation ranging from 2°to 15°,indicating they belong to low angle grain boundaries(LAGBs),while some cell walls have a misorientation of less than 2°,corresponding to dense dislocation walls(DDWs).This unique gradient structure offers an exceptional combination of strength and ductility,with a high yield strength of 522.3±1.4 MPa and an accepted elongation of 25.5±1.7%.The morphology and size of the dislocation cells remain remarkably stable after uniaxial tension,demonstrating their efficacy as effective barriers hindering dislocation movement and thus enhancing strength and hardness.This gradient dislocation-cell structure facilitates inhomogeneous plastic deformation during uniaxial tensile loading,resulting in a pronounced accumulation of geometrically necessary dislocations(GNDs).These GNDs play a significant role in conferring favorable mechanical properties by inducing hetero-deformation-induced(HDI)strengthening effects and forest hardening effects.This study presents a promising avenue for achieving the desired mechanical properties in HSLA steel.展开更多
The development of cost-effective and highly stable electrocatalysts for oxygen evolution reactions holds paramount importance in practical hydrogen production.Herein,we present a novel self-supported electrode compri...The development of cost-effective and highly stable electrocatalysts for oxygen evolution reactions holds paramount importance in practical hydrogen production.Herein,we present a novel self-supported electrode comprising Ce-doped Ni-Fe-Se nanosheets grown on carbon cloth(Ni-Fe-Ce-Se/CC).This electrode was synthesized through a selenylation process,utilizing Ni-Fe-Ce-layered double hydroxide/carbon cloth(Ni-Fe-Ce LDH/CC)as the precursor.Notably,Ni-Fe-Ce-Se/CC electrode demonstrates remarkable performance,requiring a low overpotential of 300 mV to attain a current density of 100 mA·cm^(-2)under harsh alkaline conditions.Furthermore,the electrode exhibits exceptional stability during continuous operation for 100 h.Insight into the underlying mechanisms was gained through a combination of experimental results and density functional theory calculations.Our findings reveal that Ce doping induces crystal structure deformation in Ni-Fe-Se and enhances electron enrichment around Ni atoms.This structural modification optimizes the adsorption energy of oxygen-based intermediates on the Ni-Fe-Se surface.This work offers a valuable strategy for regulating the electron transfer and adsorption capabilities of transition metal selenide electrocatalysts through RE atoms doping,opening new avenues for enhanced electrocatalytic performance.展开更多
On April 3,2024,an M 7.3 earthquake occurred in the offshore area of Hualien County,Taiwan,China.The seismogenic structure at the epicentral location was highly complex,and studying this earthquake is paramount for un...On April 3,2024,an M 7.3 earthquake occurred in the offshore area of Hualien County,Taiwan,China.The seismogenic structure at the epicentral location was highly complex,and studying this earthquake is paramount for understanding regional fault activity.In this study,we employed ascending and descending orbit Sentinel-1 Synthetic Aperture Radar(SAR)data and utilized differential interferometry(InSAR)technique to obtain the co-seismic deformation field of this event.The line-of-sight deformation field revealed that the main deformation caused by this earthquake was predominantly uplift,with maximum uplift values of approximately 38.8 cm and 46.1 cm for the ascending and descending orbits,respectively.By integrating the three-dimensional GNSS coseismic deformation field,we identified the seismogenic fault located in the offshore thrust zone east of Hualien,trending towards the northwest.The fault geometry parameters,obtained through the inversion of an elastic half-space homogeneous model,indicated an optimal fault strike of 196°,a dip angle of 30.9°,and an average strike-slip of 0.4 m and dip-slip of-2.6 m.This suggests that the predominant motion along the seismogenic fault is thrusting.The distribution of post-seismic Coulomb stress changes revealed that aftershocks mainly occurred in stress-loaded regions.However,stress loading was observed along the northern segment of the Longitudinal Valley Fault,with fewer aftershocks.This highlights the importance of closely monitoring the seismic hazard associated with this fault segment.展开更多
The Tibetan Plateau is characterized by complex geological conditions and a relatively fragile ecological environment.In recent years,there has been continuous development and increased human activity in the Tibetan P...The Tibetan Plateau is characterized by complex geological conditions and a relatively fragile ecological environment.In recent years,there has been continuous development and increased human activity in the Tibetan Plateau region,leading to a rising risk of landslides.The landslide in Banbar County,Xizang,have been perturbed by ongoing disturbances from human engineering activities,making it susceptible to instability and displaying distinct features.In this study,small baseline subset synthetic aperture radar interferometry(SBAS-InSAR)technology is used to obtain the Line of Sight(LOS)deformation velocity field in the study area,and then the slope-orientation deformation field of the landslide is obtained according to the spatial geometric relationship between the satellite’s LOS direction and the landslide.Subsequently,the landslide thickness is inverted by applying the mass conservation criterion.The results show that the movement area of the landslide is about 6.57×10^(4)m^(2),and the landslide volume is about 1.45×10^(6)m^(3).The maximum estimated thickness and average thickness of the landslide are 39 m and 22 m,respectively.The thickness estimation results align with the findings from on-site investigation,indicating the applicability of this method to large-scale earth slides.The deformation rate of the landslide exhibits a notable correlation with temperature variations,with rainfall playing a supportive role in the deformation process and displaying a certain lag.Human activities exert the most substantial influence on the spatial heterogeneity of landslide deformation,leading to the direct impact of several prominent deformation areas due to human interventions.Simultaneously,utilizing the long short-term memory(LSTM)model to predict landslide displacement,and the forecast results demonstrate the effectiveness of the LSTM model in predicting landslides that are in a continuous development and movement phase.The landslide is still active,and based on the spatial heterogeneity of landslide deformation,new recommendations have been proposed for the future management of the landslide in order to mitigate potential hazards associated with landslide instability.展开更多
Rotating Space Slender Flexible Structures(RSSFS)are extensively utilized in space operations because of their light weight,mobility,and low energy consumption.To realize the accurate space operation of the RSSFS,it i...Rotating Space Slender Flexible Structures(RSSFS)are extensively utilized in space operations because of their light weight,mobility,and low energy consumption.To realize the accurate space operation of the RSSFS,it is necessary to establish a precise mechanical model and develop a control algorithm with high precision.However,with the application of traditional control strategies,the RSSFS often suffers from the chattering phenomenon,which will aggravate structure vibration.In this paper,novel deformation description is put forward to balance modeling accuracy and computational efficiency of the RSSFS,which is better appropriate for real-time control.Besides,the Neural Network Sliding Mode Control(NNSMC)strategy modified by the hyperbolic tangent(tanh)function is put forward to compensate for modeling errors and reduce the chattering phenomenon,thereby improving the trajectory tracking accuracy of the RSSFS.Firstly,a mathematical model for the RSSFS is developed according to the novel deformation description and the vibration theory of flexible structure.Comparison of the deformation accuracy between different models proves that the novel modeling method proposed has high modeling accuracy.Next,the universal approximation property of the Radial Basis Function(RBF)neural network is put forward to determine and compensate for modeling errors,which consist of higher-order modes and the uncertainties of external disturbances.In addition,the tanh function is proposed as the reaching law in the conventional NNSMC strategy to suppress driving torque oscillation.The control law of modified NNSMC strategy and the adaptive law of weight coefficients are developed according to the Lyapunov theorem to guarantee the RSSFS stability.Finally,the simulation and physical experimental tests of the RSSFS with different control strategies are conducted.Experimental results show that the control law according to the novel deformation description and the modified NNSMC strategy can obtain accurate tracking of the rotation and reduce the vibration of the RSSFS simultaneously.展开更多
The ductility and toughness of peak-aged(PA)Mg-RE alloys are significantly influenced by their grain structure characteristics.To investigate this issue,we examined PA Mg-8.24Gd-2.68Y(wt.%)alloys with two distinct gra...The ductility and toughness of peak-aged(PA)Mg-RE alloys are significantly influenced by their grain structure characteristics.To investigate this issue,we examined PA Mg-8.24Gd-2.68Y(wt.%)alloys with two distinct grain structures:an extruded-PA sample with dynamic recrystallized(DRXed)fine grains and coarse hot-worked grains,and an extrusion-solution treated and PA sample with grown large equiaxed grains.The results showed that the extruded-PA sample demonstrated a favorable combination of tensile strength(426 MPa)and ductility(7.0%).Although intergranular microcracks nucleated in the DRXed region due to strain incompatibility,crack propagation was impeded by the DRXed fine grains,inducing intrinsic and extrinsic toughening mechanisms.On the other hand,the hot-worked grains in the extruded-PA sample initiated transgranular cracks after a relatively high strain,attributed to the strain partitioning effect,ultimately leading to failure.In comparison,the solution-treated-PA sample exhibited lower tensile strength and ductility(338 MPa and 3.7%,respectively).Intergranular cracks nucleated in the CG sample before necking,and the readily formed critical crack,facilitated by the large grain size,exhibited unstable crack growth,resulting in premature failure.This work offers valuable insights for designing high-performance PA Mg-RE alloys and preventing premature failure in practical applications.展开更多
Deformed soft-sediment deformation structures(SSDS)can indicate polyphase deformation events and provide valuable insights into the inversion process of a basin.Herein,we present the Miocene–Quaternary deformation in...Deformed soft-sediment deformation structures(SSDS)can indicate polyphase deformation events and provide valuable insights into the inversion process of a basin.Herein,we present the Miocene–Quaternary deformation inversion history of the Bomun sub-basin in the Gyeongju area of SE Korea.The inferred ENE compression direction(σHmax)based on paleostress analysis of the fault system,displacing Miocene sediments and SSDS,corresponds to the current stress field.The widespread occurrence of clear liquefaction structures and the vertical repetition of SSDS indicate substantial seismic activity during the basin opening stage.Brittle deformation features observed at both outcrop-and microstructural-scale along the faults suggest a reactivation as reverse faulting associated with a tilting process.The tectonic history of the study area is distinguished by SSDS associated with seismic activity,and reverse faulting associated with inversion process under ENE orientedσHmax.The Environmental Seismic Intensity Scale(ESI-07)based on the SSDS indicates seismic intensity of IX-X,which might be related with the opening of the Bomun sub-basin.Therefore,detailed analyses of SSDS could provide valuable insights on the dynamics of local geology and contribute to further extensive research on seismic hazards and basin inversion.展开更多
The influences of deformation conditions on grain structure and properties of 7085 aluminum alloy were investigated by optical microscopy and transmission electron microscopy in combination with tensile and fracture t...The influences of deformation conditions on grain structure and properties of 7085 aluminum alloy were investigated by optical microscopy and transmission electron microscopy in combination with tensile and fracture toughness tests. The results show that the volume fraction of dynamic recrystallization increased with the decrease of Zener-Hollomon （Z） parameter, and the volume fraction of static recrystallization increased with the increasing of Z parameter. The strength and fracture toughness of the alloy after solution and aging treatment first increased and then decreased with the increase of Z parameter. The microstructure map was established on the basis of microstructure evolution during deformation and solution heat treatment. The optimization deformation conditions were acquired under Z parameters of 1.2×10^10-9.1×10^12.展开更多
Porous titanium has been shown to exhibit desirable properties as biomedical materials. In view of the load-bearing situation, the mechanical properties and pore structure deformation behaviour of porous titanium were...Porous titanium has been shown to exhibit desirable properties as biomedical materials. In view of the load-bearing situation, the mechanical properties and pore structure deformation behaviour of porous titanium were studied. Porous titanium with porosities varying from 36%-66% and average pore size of 230 μm was fabricated by powder sintering. Microstructural features were characterized using scanning electron microscopy. Uniaxial compression tests were used to probe the mechanical response in terms of elastic modulus and compressive strength. The mechanical properties of porous titanium were found to be close to the those of human bone, with stiffness values ranging from 1.86 to 14.7 GPa and compressive strength values of 85.16-461.94 MPa. The relationships between mechanical properties and relative densities were established, and the increase in relative density showed significant effects on mechanical properties and deformations of porous titanium. In a lower relative density, the microscopic deformation mechanism of porous titanium was yielding, bending and buckling of cell walls, while the deformation of yielding and bending of cell walls was observed in the porous titanium with higher relative density.展开更多
Hot deformation behavior and microstructure evolution of TC11（Ti-6.5Al-3.5Mo-1.5Zr-0.3Si） alloy with equiaxed structure were investigated in the two-phase field at temperatures in the range of 980-800 ℃ and at stra...Hot deformation behavior and microstructure evolution of TC11（Ti-6.5Al-3.5Mo-1.5Zr-0.3Si） alloy with equiaxed structure were investigated in the two-phase field at temperatures in the range of 980-800 ℃ and at strain rates of 0.001 s-1,0.01 s-1,0.1 s-1.Effects of thermo-mechanical parameters on both of the stress—strain curves and microstructure evolution were analyzed.Grain boundary characteristics of deformation microstructures were tested by electron backscattered diffraction（EBSD）.The results reveal that β-phase dominates the deformation and presents discontinuous dynamic recrystallization at 980 ℃;meanwhile,α-phase coarsens at lower strain rates and dissolves at higher strain rates,and α-phase volume fraction and grain size decrease with increasing strain rate.Super-plastic deformation occurs at 950-900 ℃ and strain rate of 0.001 s-1.And the deformation is dominated by soft β-phase,phase interfaces and grain boundaries.Microstructural mechanism operated at 850 ℃ is continuous dynamic recrystallization of α-phase that dominates the deformation,and β-phase deforms to match the deformation of α-phase.展开更多
The recently established theory has built clear connections between hardness and toughness and electron structure involving both valence electron concentration(VEC)and core electron count(CEC)in transition metal nitri...The recently established theory has built clear connections between hardness and toughness and electron structure involving both valence electron concentration(VEC)and core electron count(CEC)in transition metal nitride(TMN)ceramics.However,the underlying deformation mechanisms remain unclear.Herein,we conduct in-depth analysis on microstructure evolution during deformation of the high VEC-CEC solution TiMoN coatings having desired combination of high hardness and toughness.The effects of solid solution,preferred orientation linked with symbiotic compressive stress,grain size and dislocations are systematically discussed.We discover that numerous dislocations have been implanted into the nanocrystals of the TiMoN coating during the high-ionization arc deposition.Using two-beam bright-field imaging,we count the dislocation density and confirm occurrence of dislocation multiplication to form effective plastic deformation,which contributes to significant strain hardening,comparable to solid solution hardening,fine-grain hardening and compressive stress hardening.The improved dislocation activities also play a crucial role in enhancing the toughness by providing extra energy dissipation paths.This work gains new insights into the origins of mechanical properties of ceramic coatings and possibility to tune them via defects.展开更多
As a key storage facility, the structural safety of large oil tanks is directly related to the stable operation of the energy system. The static pressure caused by the change of liquid level is one of the main loads i...As a key storage facility, the structural safety of large oil tanks is directly related to the stable operation of the energy system. The static pressure caused by the change of liquid level is one of the main loads in the service process of storage tanks, which determines the structural deformation and damage risk. To explore the structural deformation properties under the change of liquid levels and provide a theoretical basis for the prevention and control of damage risk, this paper systematically analyzes the mechanical response of storage tanks under the pressures induced by different liquid levels based on the shell theory. Combined with the finite element software COMSOL, the radial displacement and stress-strain distribution under different liquid levels are simulated to verify the accuracy and effectiveness of the proposed theoretical model. The increase in liquid level and radius aggravates the radial deformation and makes the risk point move up, while the increase in wall thickness can effectively reduce the deformation response. Suggestions on the monitoring zone and damage risk prevention measures have also been given to instruct the safe operation of oil tanks. The research provides theoretical support for the optimization design of storage tank structures, the construction of advanced structural health monitoring system and the prevention and control of damage risk.展开更多
The investigation of the tectonic deformation characteristics at the front margin of the Xu-Su arc tectonic belt provides important reference points for identifying and analyzing its genetic mechanism,tectonic evoluti...The investigation of the tectonic deformation characteristics at the front margin of the Xu-Su arc tectonic belt provides important reference points for identifying and analyzing its genetic mechanism,tectonic evolution process,and the latest evidence of tectonic deformation.In this study,two reflection seismic exploration profiles across the front margin of the Xu-Su arc tectonic belt are utilized to reveal that the Qinglongshan fault is the thrust fault of its front margin boundary.The kinematic properties and tectonic deformation characteristics of the internal faults in the front margin basin are also obtained.Using the Qinglongshan fault as the boundary,the middle and posterior margins of the Xu-Su arc tectonic belt are composed of numerous thrust faults,which suggest strong ancient tectonic movement.However,a large number of normal faults are developed within the front margin basin,with some faults exhibiting strike-slip and growth properties,which indicate strong neotectonic movement.Results reveal that the Xu-Su arc tectonic belt is a large-scale thrust-nappe structure that has undergone structural inversion.The Xu-Su arc tectonic belt experienced strong tectonic activity during the Middle Pleistocene,and the most recent tectonic deformation has extended into the front margin basin interior.展开更多
For deep prospects in the foreland thrust belt,southern Junggar Basin,NW China,there are uncertainties in factors controlling the structural deformation,distribution of paleo-structures and detachment layers,and distr...For deep prospects in the foreland thrust belt,southern Junggar Basin,NW China,there are uncertainties in factors controlling the structural deformation,distribution of paleo-structures and detachment layers,and distribution of major hydrocarbon source rocks.Based on the latest 3D seismic,gravity-magnetic,and drilling data,together with the results of previous structural physical simulation and discrete element numerical simulation experiments,the spatial distribution of pre-existing paleo-structures and detachment layers in deep strata of southern Junggar Basin were systematically characterized,the structural deformation characteristics and formation mechanisms were analyzed,the distribution patterns of multiple hydrocarbon source rock suites were clarified,and hydrocarbon accumulation features in key zones were reassessed.The exploration targets in deep lower assemblages with possibility of breakthrough were expected.Key results are obtained in three aspects.First,structural deformation is controlled by two-stage paleo-structures and three detachment layers with distinct lateral variations:the Jurassic layer(moderate thickness,wide distribution),the Cretaceous layer(thickest but weak detachment),and the Paleogene layer(thin but long-distance lateral thrusting).Accordingly,a four-layer composite deformation sequence was identified,and the structural genetic model with paleo-bulge controlling zonation by segments laterally and multiple detachment layers controlling sequence vertically.Second,the Permian source rocks show a distribution pattern with narrow trough(west),multiple sags(central),and broad basin(east),which is depicted by combining high-precision gravity-magnetic data and time-frequency electromagnetic data for the first time,and the Jurassic source rocks feature thicker mudstones in the west and rich coals in the east according to the reassessment.Third,two petroleum systems and a four-layer composite hydrocarbon accumulation model are established depending on the structural deformation strength,trap effectiveness and source-trap configuration.The southern Junggar Basin is divided into three segments with ten zones,and a hierarchical exploration strategy is proposed for deep lower assemblages in this region,that is,focusing on five priority zones,expanding to three potential areas,and challenging two high-risk targets.展开更多
The intersection is a widely used traffic line structure from the shallow tunnel to the deep roadway,and determining the subsidence hidden danger area of the roof is the key to its stability control.However,applying t...The intersection is a widely used traffic line structure from the shallow tunnel to the deep roadway,and determining the subsidence hidden danger area of the roof is the key to its stability control.However,applying traditional maximum equivalent span beam(MESB)theory to determine deformation range,peak point,and angle influence poses a challenge.Considering the overall structure of the intersection roof,the maximum equivalent triangular plate(METP)theory is proposed,and its geometric parameter calculation formula and deflection calculation formula are obtained.The application of the two theories in 18 models with different intersection angles,roadway types,and surrounding rock lithology is verified by numerical analysis.The results show that:1)The METP structure of the intersection roof established by the simulation results of each model successfully determined the location of the roof’s high displacement zone;2)The area comparison method of the METP theory can be reasonably explained:①The roof subsidence of the intersection decreases with the increase of the intersection angle;②The roof subsidence at the intersection of different roadway types has a rectangular type>arch type>circular type;③The roof subsidence of the intersection with weak surrounding rock is significantly larger than that of the intersection with hard surrounding rock.According to the application results of the two theories,the four advantages of the METP theory are compared and clarified in the basic assumptions,mechanical models,main viewpoints,and mechanism analysis.The large deformation inducement of the intersection roof is then explored.The J 2 peak area of the roof drives the large deformation of the area,the peak point of which is consistent with the center of gravity position of the METP.Furthermore,the change in the range of this peak is consistent with the change law of the METP’s area.Hence,this theory clarifies the large deformation area of the intersection roof,which provides a clear guiding basis for its initial support design,mid-term monitoring,and late local reinforcement.展开更多
To investigate the residual stress distribution and its influence on machining deformation in 6061-T651 aluminum alloy plates,this paper uses the crack compliance method to study the residual stress characteristics of...To investigate the residual stress distribution and its influence on machining deformation in 6061-T651 aluminum alloy plates,this paper uses the crack compliance method to study the residual stress characteristics of 6061-T651 aluminum alloy plates with a thickness of 75 mm produced by two domestic manufacturers in China.The results indicate that both types of plates exhibit highly consistent and symmetrical M-shaped residual stress profile along the thickness direction,manifested as surface layer compression and core tension.The strain energy density across all specimens ranges from 1.27 kJ/m^(3)to 1.43 kJ/m^(3).Machining deformation simulations of an aerospace component incorporating these measured stresses showed minimal final deformation difference between the material sources,with a maximum deviation of only 0.009 mm across specimens.These findings provide critical data for material selection and deformation control in aerospace manufacturing.展开更多
1.Introduction The strength-ductility trade-offdilemma has long been a per-sistent challenge in Al matrix composites(AMCs)[1,2].This is-sue primarily arises from the agglomeration of reinforcements at the grain bounda...1.Introduction The strength-ductility trade-offdilemma has long been a per-sistent challenge in Al matrix composites(AMCs)[1,2].This is-sue primarily arises from the agglomeration of reinforcements at the grain boundaries(GBs),which restricts local plastic flow dur-ing the plastic deformation and leads to stress concentration[3,4].Recently,the development of concepts aimed at achieving hetero-geneous grain has emerged as a promising approach for enhanc-ing comprehensive mechanical properties[5,6].展开更多
This study identified soft-sediment deformation structures （SSDS） of seismic origin from lacustrine sediments in the late Quaternary paleo-dammed lake at Tashkorgan, northeastern Pamir. The observed deformation stru...This study identified soft-sediment deformation structures （SSDS） of seismic origin from lacustrine sediments in the late Quaternary paleo-dammed lake at Tashkorgan, northeastern Pamir. The observed deformation structures include sand dykes, liquefied diapir and convolute structures, gravity induced SSDS, and thixotropic pillar and tabular structures. We conducted a preliminary study on the morphology, formation and trigger mechanisms of pillar and tabular structures formed by liquefaction of underlying coarse sand and thixotropy of the upper silty clay. The regional tectonic setting and distribution of lacustrine strata indicate that the most probable trigger for the SSDS in lacustrine sediments was seismic activity, with an approximate earthquake magnitude of M〉6.0; the potential seismogenic fault is the southern part of the Kongur normal fault extensional system. AMS ^4C dating results indicate that the SSDS were formed by seismic events occurring between 26050±100 yrBP and 22710±80 yrBP, implying intense fault activity in this region during the late Pleistocene. This study provides new evidence for understanding tectonic activity and regional geodynamics in western China.展开更多
The structural evolution of tectonically deformed coals （TDC） with different deformational mechanisms and different deformational intensities are investigated in depth through X-ray diffraction （XRD） analysis on 3...The structural evolution of tectonically deformed coals （TDC） with different deformational mechanisms and different deformational intensities are investigated in depth through X-ray diffraction （XRD） analysis on 31 samples of different metamorphic grades （R ： 0.7%-3.1%） collected from the Huaibei coalfield. The results indicated that there are different evolution characteristics between the ductile and brittle deformational coals with increasing of metamorphism and deformation. On the one hand, with the increase of metamorphism, the atomic plane spacing （d002） is decreasing at step velocity, the stacking of the BSU layer （Lc） is increasing at first and then decreasing, but the extension of the BSU layer （La） and the ratio of La/Lc are decreasing initially and then increasing. On the other hand, for the brittle deformational coal, d002 is increasing initially and then decreasing, which causes an inversion of the variation of Lc and La under the lower-middle or higher-middle metamorphism grade when the deformational intensity was increasing. In contrast, in the ductile deformational coals, d002 decreased initially and then increased, and the value of L~ decreased with the increase of deformational intensity. But the value of La increased under the lower-middle metamorphism grade and increased at first and then decreased under the higher-middle metamorphism grade. We conclude that the degradation and polycondensation of TDC macromolecular structure can be obviously impacted during the ductile deformational process, because the increase and accumulation of unit dislocation perhaps transforms the stress into strain energy. Meanwhile, the brittle deformation can transform the stress into frictional heat energy, and promote the metamorphism and degradation as well. It can be concluded that deformation is more important than metamorphism to the differential evolution of the ductile and brittle deformational coals.展开更多
High-resolution lithospheric structure is essential for understanding the tectonic evolution and deformation patterns of the southeastern Tibetan plateau. This is now possible due to recent advances in ambient noise a...High-resolution lithospheric structure is essential for understanding the tectonic evolution and deformation patterns of the southeastern Tibetan plateau. This is now possible due to recent advances in ambient noise and earthquake surface wave tomography, and great improvements in data coverage from dense portable array stations deployed in SE Tibet. In this review paper, I first give a brief overview of the tomographic methods from ambient noise and earthquake surface waves, and then summarize the major findings about the lithospheric structure and deformation in SE Tibet revealed by ambient noise and earthquake surface wave tomography as well as by other seismic and geophysical observations. These findings mainly include the 3-D distribution of mechanically weak zones in the mid-lower crust, lateral and vertical variations in radial and azimuthal anisotropy, possible interplay of some fault zones with crustal weak zones, and importance of strike-slip faulting on upper crustal deformation. These results suggest that integration of block extrusion in the more rigid upper-middle crust and channel flow in the more ductile mid-lower crust will be more compatible with the current geophysical observations. Finally I discuss some future perspective researches in SE Tibet, including array-based tomography, joint inversion using multiple seismic data, and integration of geodynamic modeling and seismic observations.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.U1910212)the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘There is a pressing need for high-performance,high-strength low-alloy structural(HSLA)steels in various engineering fields,such as hydraulic components,engineering machinery,bridges,ships,and pressure vessels.In this study,a gradient dislocation-cell structure is introduced into an HSLA steel through ultrasonic severe surface rolling.The cell size is approximately 614 nm at the topmost surface layer,and increases with increasing the depth.Most of the cell walls have a misorientation ranging from 2°to 15°,indicating they belong to low angle grain boundaries(LAGBs),while some cell walls have a misorientation of less than 2°,corresponding to dense dislocation walls(DDWs).This unique gradient structure offers an exceptional combination of strength and ductility,with a high yield strength of 522.3±1.4 MPa and an accepted elongation of 25.5±1.7%.The morphology and size of the dislocation cells remain remarkably stable after uniaxial tension,demonstrating their efficacy as effective barriers hindering dislocation movement and thus enhancing strength and hardness.This gradient dislocation-cell structure facilitates inhomogeneous plastic deformation during uniaxial tensile loading,resulting in a pronounced accumulation of geometrically necessary dislocations(GNDs).These GNDs play a significant role in conferring favorable mechanical properties by inducing hetero-deformation-induced(HDI)strengthening effects and forest hardening effects.This study presents a promising avenue for achieving the desired mechanical properties in HSLA steel.
基金supported by the National Key Technology R&D Program of China(Nos.2021YFB3500801,2022YFB3504302 and 2022YFC3901503)the Natural Science Foundation and Overseas Talent Projects of Jiangxi Province(Nos.0232BAB214025 and 20232BCJ25044)the Double Thousand Plan of Jiangxi Province(No.jxsq2023201002).
文摘The development of cost-effective and highly stable electrocatalysts for oxygen evolution reactions holds paramount importance in practical hydrogen production.Herein,we present a novel self-supported electrode comprising Ce-doped Ni-Fe-Se nanosheets grown on carbon cloth(Ni-Fe-Ce-Se/CC).This electrode was synthesized through a selenylation process,utilizing Ni-Fe-Ce-layered double hydroxide/carbon cloth(Ni-Fe-Ce LDH/CC)as the precursor.Notably,Ni-Fe-Ce-Se/CC electrode demonstrates remarkable performance,requiring a low overpotential of 300 mV to attain a current density of 100 mA·cm^(-2)under harsh alkaline conditions.Furthermore,the electrode exhibits exceptional stability during continuous operation for 100 h.Insight into the underlying mechanisms was gained through a combination of experimental results and density functional theory calculations.Our findings reveal that Ce doping induces crystal structure deformation in Ni-Fe-Se and enhances electron enrichment around Ni atoms.This structural modification optimizes the adsorption energy of oxygen-based intermediates on the Ni-Fe-Se surface.This work offers a valuable strategy for regulating the electron transfer and adsorption capabilities of transition metal selenide electrocatalysts through RE atoms doping,opening new avenues for enhanced electrocatalytic performance.
基金supported by Shaanxi Province Natural Science Foundation Research Program[Grant number 2023JC-QN-0296]。
文摘On April 3,2024,an M 7.3 earthquake occurred in the offshore area of Hualien County,Taiwan,China.The seismogenic structure at the epicentral location was highly complex,and studying this earthquake is paramount for understanding regional fault activity.In this study,we employed ascending and descending orbit Sentinel-1 Synthetic Aperture Radar(SAR)data and utilized differential interferometry(InSAR)technique to obtain the co-seismic deformation field of this event.The line-of-sight deformation field revealed that the main deformation caused by this earthquake was predominantly uplift,with maximum uplift values of approximately 38.8 cm and 46.1 cm for the ascending and descending orbits,respectively.By integrating the three-dimensional GNSS coseismic deformation field,we identified the seismogenic fault located in the offshore thrust zone east of Hualien,trending towards the northwest.The fault geometry parameters,obtained through the inversion of an elastic half-space homogeneous model,indicated an optimal fault strike of 196°,a dip angle of 30.9°,and an average strike-slip of 0.4 m and dip-slip of-2.6 m.This suggests that the predominant motion along the seismogenic fault is thrusting.The distribution of post-seismic Coulomb stress changes revealed that aftershocks mainly occurred in stress-loaded regions.However,stress loading was observed along the northern segment of the Longitudinal Valley Fault,with fewer aftershocks.This highlights the importance of closely monitoring the seismic hazard associated with this fault segment.
基金supported by the second Tibetan Plateau Scientific Expedition and Research(STEP)program(Grant NO.2019QZKK0904)the National Natural Science Foundation of China(Grant No.41941019)the National Natural Science Foundation of China(Grant NO.42307217)。
文摘The Tibetan Plateau is characterized by complex geological conditions and a relatively fragile ecological environment.In recent years,there has been continuous development and increased human activity in the Tibetan Plateau region,leading to a rising risk of landslides.The landslide in Banbar County,Xizang,have been perturbed by ongoing disturbances from human engineering activities,making it susceptible to instability and displaying distinct features.In this study,small baseline subset synthetic aperture radar interferometry(SBAS-InSAR)technology is used to obtain the Line of Sight(LOS)deformation velocity field in the study area,and then the slope-orientation deformation field of the landslide is obtained according to the spatial geometric relationship between the satellite’s LOS direction and the landslide.Subsequently,the landslide thickness is inverted by applying the mass conservation criterion.The results show that the movement area of the landslide is about 6.57×10^(4)m^(2),and the landslide volume is about 1.45×10^(6)m^(3).The maximum estimated thickness and average thickness of the landslide are 39 m and 22 m,respectively.The thickness estimation results align with the findings from on-site investigation,indicating the applicability of this method to large-scale earth slides.The deformation rate of the landslide exhibits a notable correlation with temperature variations,with rainfall playing a supportive role in the deformation process and displaying a certain lag.Human activities exert the most substantial influence on the spatial heterogeneity of landslide deformation,leading to the direct impact of several prominent deformation areas due to human interventions.Simultaneously,utilizing the long short-term memory(LSTM)model to predict landslide displacement,and the forecast results demonstrate the effectiveness of the LSTM model in predicting landslides that are in a continuous development and movement phase.The landslide is still active,and based on the spatial heterogeneity of landslide deformation,new recommendations have been proposed for the future management of the landslide in order to mitigate potential hazards associated with landslide instability.
基金Supported by the Applied Basic Research Program of Liaoning Province,China(No.2023JH2/101300159)the National Natural Science Foundation of China(No.52275090).
文摘Rotating Space Slender Flexible Structures(RSSFS)are extensively utilized in space operations because of their light weight,mobility,and low energy consumption.To realize the accurate space operation of the RSSFS,it is necessary to establish a precise mechanical model and develop a control algorithm with high precision.However,with the application of traditional control strategies,the RSSFS often suffers from the chattering phenomenon,which will aggravate structure vibration.In this paper,novel deformation description is put forward to balance modeling accuracy and computational efficiency of the RSSFS,which is better appropriate for real-time control.Besides,the Neural Network Sliding Mode Control(NNSMC)strategy modified by the hyperbolic tangent(tanh)function is put forward to compensate for modeling errors and reduce the chattering phenomenon,thereby improving the trajectory tracking accuracy of the RSSFS.Firstly,a mathematical model for the RSSFS is developed according to the novel deformation description and the vibration theory of flexible structure.Comparison of the deformation accuracy between different models proves that the novel modeling method proposed has high modeling accuracy.Next,the universal approximation property of the Radial Basis Function(RBF)neural network is put forward to determine and compensate for modeling errors,which consist of higher-order modes and the uncertainties of external disturbances.In addition,the tanh function is proposed as the reaching law in the conventional NNSMC strategy to suppress driving torque oscillation.The control law of modified NNSMC strategy and the adaptive law of weight coefficients are developed according to the Lyapunov theorem to guarantee the RSSFS stability.Finally,the simulation and physical experimental tests of the RSSFS with different control strategies are conducted.Experimental results show that the control law according to the novel deformation description and the modified NNSMC strategy can obtain accurate tracking of the rotation and reduce the vibration of the RSSFS simultaneously.
基金supported by the Defense Industrial Technology Development Program(No.JCKY2018407C008)the NCST Science Fund for Distinguished Young Scholars(No.JQ201702).
文摘The ductility and toughness of peak-aged(PA)Mg-RE alloys are significantly influenced by their grain structure characteristics.To investigate this issue,we examined PA Mg-8.24Gd-2.68Y(wt.%)alloys with two distinct grain structures:an extruded-PA sample with dynamic recrystallized(DRXed)fine grains and coarse hot-worked grains,and an extrusion-solution treated and PA sample with grown large equiaxed grains.The results showed that the extruded-PA sample demonstrated a favorable combination of tensile strength(426 MPa)and ductility(7.0%).Although intergranular microcracks nucleated in the DRXed region due to strain incompatibility,crack propagation was impeded by the DRXed fine grains,inducing intrinsic and extrinsic toughening mechanisms.On the other hand,the hot-worked grains in the extruded-PA sample initiated transgranular cracks after a relatively high strain,attributed to the strain partitioning effect,ultimately leading to failure.In comparison,the solution-treated-PA sample exhibited lower tensile strength and ductility(338 MPa and 3.7%,respectively).Intergranular cracks nucleated in the CG sample before necking,and the readily formed critical crack,facilitated by the large grain size,exhibited unstable crack growth,resulting in premature failure.This work offers valuable insights for designing high-performance PA Mg-RE alloys and preventing premature failure in practical applications.
基金supported by a grant(2022-MOIS62-001(RS-2022-ND640011))from the National Disaster Risk AnalysisManagement Technology in Earthquake funded by the Ministry of Interior and Safety(MOIS,Korea).
文摘Deformed soft-sediment deformation structures(SSDS)can indicate polyphase deformation events and provide valuable insights into the inversion process of a basin.Herein,we present the Miocene–Quaternary deformation inversion history of the Bomun sub-basin in the Gyeongju area of SE Korea.The inferred ENE compression direction(σHmax)based on paleostress analysis of the fault system,displacing Miocene sediments and SSDS,corresponds to the current stress field.The widespread occurrence of clear liquefaction structures and the vertical repetition of SSDS indicate substantial seismic activity during the basin opening stage.Brittle deformation features observed at both outcrop-and microstructural-scale along the faults suggest a reactivation as reverse faulting associated with a tilting process.The tectonic history of the study area is distinguished by SSDS associated with seismic activity,and reverse faulting associated with inversion process under ENE orientedσHmax.The Environmental Seismic Intensity Scale(ESI-07)based on the SSDS indicates seismic intensity of IX-X,which might be related with the opening of the Bomun sub-basin.Therefore,detailed analyses of SSDS could provide valuable insights on the dynamics of local geology and contribute to further extensive research on seismic hazards and basin inversion.
基金Projects (2010CB731701, 2012CB619502) supported by National Basic Research Program of ChinaProject (51021063) supported by Creative Research Group of National Natural Science Foundation of ChinaProject (CX2012B043) supported by Hunan Provincial Innovation Foundation for Postgraduate
文摘The influences of deformation conditions on grain structure and properties of 7085 aluminum alloy were investigated by optical microscopy and transmission electron microscopy in combination with tensile and fracture toughness tests. The results show that the volume fraction of dynamic recrystallization increased with the decrease of Zener-Hollomon （Z） parameter, and the volume fraction of static recrystallization increased with the increasing of Z parameter. The strength and fracture toughness of the alloy after solution and aging treatment first increased and then decreased with the increase of Z parameter. The microstructure map was established on the basis of microstructure evolution during deformation and solution heat treatment. The optimization deformation conditions were acquired under Z parameters of 1.2×10^10-9.1×10^12.
基金Project(2012CB619101)supported by the National Basic Research Program of China
文摘Porous titanium has been shown to exhibit desirable properties as biomedical materials. In view of the load-bearing situation, the mechanical properties and pore structure deformation behaviour of porous titanium were studied. Porous titanium with porosities varying from 36%-66% and average pore size of 230 μm was fabricated by powder sintering. Microstructural features were characterized using scanning electron microscopy. Uniaxial compression tests were used to probe the mechanical response in terms of elastic modulus and compressive strength. The mechanical properties of porous titanium were found to be close to the those of human bone, with stiffness values ranging from 1.86 to 14.7 GPa and compressive strength values of 85.16-461.94 MPa. The relationships between mechanical properties and relative densities were established, and the increase in relative density showed significant effects on mechanical properties and deformations of porous titanium. In a lower relative density, the microscopic deformation mechanism of porous titanium was yielding, bending and buckling of cell walls, while the deformation of yielding and bending of cell walls was observed in the porous titanium with higher relative density.
基金Project(2008011045) supported by the Natural Science Foundation of Shanxi Province,China
文摘Hot deformation behavior and microstructure evolution of TC11（Ti-6.5Al-3.5Mo-1.5Zr-0.3Si） alloy with equiaxed structure were investigated in the two-phase field at temperatures in the range of 980-800 ℃ and at strain rates of 0.001 s-1,0.01 s-1,0.1 s-1.Effects of thermo-mechanical parameters on both of the stress—strain curves and microstructure evolution were analyzed.Grain boundary characteristics of deformation microstructures were tested by electron backscattered diffraction（EBSD）.The results reveal that β-phase dominates the deformation and presents discontinuous dynamic recrystallization at 980 ℃;meanwhile,α-phase coarsens at lower strain rates and dissolves at higher strain rates,and α-phase volume fraction and grain size decrease with increasing strain rate.Super-plastic deformation occurs at 950-900 ℃ and strain rate of 0.001 s-1.And the deformation is dominated by soft β-phase,phase interfaces and grain boundaries.Microstructural mechanism operated at 850 ℃ is continuous dynamic recrystallization of α-phase that dominates the deformation,and β-phase deforms to match the deformation of α-phase.
基金supported by the Distinguished Young Scholars of China(No.52025014)Natural Science Foundation of Zhejiang Province(No.LQ23E010002)Innovation 2025 Major Project of Ningbo(Nos.2022Z011 and 2023Z022).
文摘The recently established theory has built clear connections between hardness and toughness and electron structure involving both valence electron concentration(VEC)and core electron count(CEC)in transition metal nitride(TMN)ceramics.However,the underlying deformation mechanisms remain unclear.Herein,we conduct in-depth analysis on microstructure evolution during deformation of the high VEC-CEC solution TiMoN coatings having desired combination of high hardness and toughness.The effects of solid solution,preferred orientation linked with symbiotic compressive stress,grain size and dislocations are systematically discussed.We discover that numerous dislocations have been implanted into the nanocrystals of the TiMoN coating during the high-ionization arc deposition.Using two-beam bright-field imaging,we count the dislocation density and confirm occurrence of dislocation multiplication to form effective plastic deformation,which contributes to significant strain hardening,comparable to solid solution hardening,fine-grain hardening and compressive stress hardening.The improved dislocation activities also play a crucial role in enhancing the toughness by providing extra energy dissipation paths.This work gains new insights into the origins of mechanical properties of ceramic coatings and possibility to tune them via defects.
基金supported by Fundamental Research Funds for the Central Universities(No.lzujbky-2024-05)Innovation Foundation of Provincial Education Department of Gansu(2024B-005)+1 种基金Scientific Department of Gansu(24CXGA083,24CXGA024,JK2024-28,JK2024-32,23CXJA0007)Industrial Support Plan Project of Provincial Education Department of Gansu(2025CYZC-003 and CYZC-2024-10).
文摘As a key storage facility, the structural safety of large oil tanks is directly related to the stable operation of the energy system. The static pressure caused by the change of liquid level is one of the main loads in the service process of storage tanks, which determines the structural deformation and damage risk. To explore the structural deformation properties under the change of liquid levels and provide a theoretical basis for the prevention and control of damage risk, this paper systematically analyzes the mechanical response of storage tanks under the pressures induced by different liquid levels based on the shell theory. Combined with the finite element software COMSOL, the radial displacement and stress-strain distribution under different liquid levels are simulated to verify the accuracy and effectiveness of the proposed theoretical model. The increase in liquid level and radius aggravates the radial deformation and makes the risk point move up, while the increase in wall thickness can effectively reduce the deformation response. Suggestions on the monitoring zone and damage risk prevention measures have also been given to instruct the safe operation of oil tanks. The research provides theoretical support for the optimization design of storage tank structures, the construction of advanced structural health monitoring system and the prevention and control of damage risk.
基金The active fault exploration and seismic risk assessment project of Huaibei and the research and development project of Beijing Disaster Prevention Technology Co.,Ltd.(FZKJYF202201)jointly funded this work。
文摘The investigation of the tectonic deformation characteristics at the front margin of the Xu-Su arc tectonic belt provides important reference points for identifying and analyzing its genetic mechanism,tectonic evolution process,and the latest evidence of tectonic deformation.In this study,two reflection seismic exploration profiles across the front margin of the Xu-Su arc tectonic belt are utilized to reveal that the Qinglongshan fault is the thrust fault of its front margin boundary.The kinematic properties and tectonic deformation characteristics of the internal faults in the front margin basin are also obtained.Using the Qinglongshan fault as the boundary,the middle and posterior margins of the Xu-Su arc tectonic belt are composed of numerous thrust faults,which suggest strong ancient tectonic movement.However,a large number of normal faults are developed within the front margin basin,with some faults exhibiting strike-slip and growth properties,which indicate strong neotectonic movement.Results reveal that the Xu-Su arc tectonic belt is a large-scale thrust-nappe structure that has undergone structural inversion.The Xu-Su arc tectonic belt experienced strong tectonic activity during the Middle Pleistocene,and the most recent tectonic deformation has extended into the front margin basin interior.
基金Supported by the Science and Technology Special Project of CNPC(2023YQX10111)Key Research and Development Special Project of Xinjiang Uygur Autonomous Region(2024B01015-3)。
文摘For deep prospects in the foreland thrust belt,southern Junggar Basin,NW China,there are uncertainties in factors controlling the structural deformation,distribution of paleo-structures and detachment layers,and distribution of major hydrocarbon source rocks.Based on the latest 3D seismic,gravity-magnetic,and drilling data,together with the results of previous structural physical simulation and discrete element numerical simulation experiments,the spatial distribution of pre-existing paleo-structures and detachment layers in deep strata of southern Junggar Basin were systematically characterized,the structural deformation characteristics and formation mechanisms were analyzed,the distribution patterns of multiple hydrocarbon source rock suites were clarified,and hydrocarbon accumulation features in key zones were reassessed.The exploration targets in deep lower assemblages with possibility of breakthrough were expected.Key results are obtained in three aspects.First,structural deformation is controlled by two-stage paleo-structures and three detachment layers with distinct lateral variations:the Jurassic layer(moderate thickness,wide distribution),the Cretaceous layer(thickest but weak detachment),and the Paleogene layer(thin but long-distance lateral thrusting).Accordingly,a four-layer composite deformation sequence was identified,and the structural genetic model with paleo-bulge controlling zonation by segments laterally and multiple detachment layers controlling sequence vertically.Second,the Permian source rocks show a distribution pattern with narrow trough(west),multiple sags(central),and broad basin(east),which is depicted by combining high-precision gravity-magnetic data and time-frequency electromagnetic data for the first time,and the Jurassic source rocks feature thicker mudstones in the west and rich coals in the east according to the reassessment.Third,two petroleum systems and a four-layer composite hydrocarbon accumulation model are established depending on the structural deformation strength,trap effectiveness and source-trap configuration.The southern Junggar Basin is divided into three segments with ten zones,and a hierarchical exploration strategy is proposed for deep lower assemblages in this region,that is,focusing on five priority zones,expanding to three potential areas,and challenging two high-risk targets.
基金Project(52204164)supported by the National Natural Science Foundation of ChinaProject(2021QNRC001)supported by the Young Elite Scientists Sponsorship Program by CAST,China。
文摘The intersection is a widely used traffic line structure from the shallow tunnel to the deep roadway,and determining the subsidence hidden danger area of the roof is the key to its stability control.However,applying traditional maximum equivalent span beam(MESB)theory to determine deformation range,peak point,and angle influence poses a challenge.Considering the overall structure of the intersection roof,the maximum equivalent triangular plate(METP)theory is proposed,and its geometric parameter calculation formula and deflection calculation formula are obtained.The application of the two theories in 18 models with different intersection angles,roadway types,and surrounding rock lithology is verified by numerical analysis.The results show that:1)The METP structure of the intersection roof established by the simulation results of each model successfully determined the location of the roof’s high displacement zone;2)The area comparison method of the METP theory can be reasonably explained:①The roof subsidence of the intersection decreases with the increase of the intersection angle;②The roof subsidence at the intersection of different roadway types has a rectangular type>arch type>circular type;③The roof subsidence of the intersection with weak surrounding rock is significantly larger than that of the intersection with hard surrounding rock.According to the application results of the two theories,the four advantages of the METP theory are compared and clarified in the basic assumptions,mechanical models,main viewpoints,and mechanism analysis.The large deformation inducement of the intersection roof is then explored.The J 2 peak area of the roof drives the large deformation of the area,the peak point of which is consistent with the center of gravity position of the METP.Furthermore,the change in the range of this peak is consistent with the change law of the METP’s area.Hence,this theory clarifies the large deformation area of the intersection roof,which provides a clear guiding basis for its initial support design,mid-term monitoring,and late local reinforcement.
基金supported in part by the National Natural Science Foundation of China(Nos.61201048,61107063)the National Science and Technology Major Project(No.2017-VI-001-0094).
文摘To investigate the residual stress distribution and its influence on machining deformation in 6061-T651 aluminum alloy plates,this paper uses the crack compliance method to study the residual stress characteristics of 6061-T651 aluminum alloy plates with a thickness of 75 mm produced by two domestic manufacturers in China.The results indicate that both types of plates exhibit highly consistent and symmetrical M-shaped residual stress profile along the thickness direction,manifested as surface layer compression and core tension.The strain energy density across all specimens ranges from 1.27 kJ/m^(3)to 1.43 kJ/m^(3).Machining deformation simulations of an aerospace component incorporating these measured stresses showed minimal final deformation difference between the material sources,with a maximum deviation of only 0.009 mm across specimens.These findings provide critical data for material selection and deformation control in aerospace manufacturing.
基金support by the National Natural Science Foundation of China(Grant Nos.U23A20546 and 52271010)the Chinese National Natural Science Fund for Distinguished Young Scholars(Grant No.52025015)the Natural Science Foundation of Tianjin City(No.21JCZDJC00510).
文摘1.Introduction The strength-ductility trade-offdilemma has long been a per-sistent challenge in Al matrix composites(AMCs)[1,2].This is-sue primarily arises from the agglomeration of reinforcements at the grain boundaries(GBs),which restricts local plastic flow dur-ing the plastic deformation and leads to stress concentration[3,4].Recently,the development of concepts aimed at achieving hetero-geneous grain has emerged as a promising approach for enhanc-ing comprehensive mechanical properties[5,6].
基金financially supported by the National Natural Science Foundation of China (41702372)the Open Fund of State Key Laboratory of Earthquake Dynamics (LED2017B03)
文摘This study identified soft-sediment deformation structures （SSDS） of seismic origin from lacustrine sediments in the late Quaternary paleo-dammed lake at Tashkorgan, northeastern Pamir. The observed deformation structures include sand dykes, liquefied diapir and convolute structures, gravity induced SSDS, and thixotropic pillar and tabular structures. We conducted a preliminary study on the morphology, formation and trigger mechanisms of pillar and tabular structures formed by liquefaction of underlying coarse sand and thixotropy of the upper silty clay. The regional tectonic setting and distribution of lacustrine strata indicate that the most probable trigger for the SSDS in lacustrine sediments was seismic activity, with an approximate earthquake magnitude of M〉6.0; the potential seismogenic fault is the southern part of the Kongur normal fault extensional system. AMS ^4C dating results indicate that the SSDS were formed by seismic events occurring between 26050±100 yrBP and 22710±80 yrBP, implying intense fault activity in this region during the late Pleistocene. This study provides new evidence for understanding tectonic activity and regional geodynamics in western China.
基金supported by the National Natural Science Foundation of China(Grant Nos.41030422, 40972131,40772135 and 41202120)the National Basic Research Program of China(Grant Nos.2009CB219601 and 2006CB202201)the China Postdoctoral Science Foundation Funded Project(2012M510590)
文摘The structural evolution of tectonically deformed coals （TDC） with different deformational mechanisms and different deformational intensities are investigated in depth through X-ray diffraction （XRD） analysis on 31 samples of different metamorphic grades （R ： 0.7%-3.1%） collected from the Huaibei coalfield. The results indicated that there are different evolution characteristics between the ductile and brittle deformational coals with increasing of metamorphism and deformation. On the one hand, with the increase of metamorphism, the atomic plane spacing （d002） is decreasing at step velocity, the stacking of the BSU layer （Lc） is increasing at first and then decreasing, but the extension of the BSU layer （La） and the ratio of La/Lc are decreasing initially and then increasing. On the other hand, for the brittle deformational coal, d002 is increasing initially and then decreasing, which causes an inversion of the variation of Lc and La under the lower-middle or higher-middle metamorphism grade when the deformational intensity was increasing. In contrast, in the ductile deformational coals, d002 decreased initially and then increased, and the value of L~ decreased with the increase of deformational intensity. But the value of La increased under the lower-middle metamorphism grade and increased at first and then decreased under the higher-middle metamorphism grade. We conclude that the degradation and polycondensation of TDC macromolecular structure can be obviously impacted during the ductile deformational process, because the increase and accumulation of unit dislocation perhaps transforms the stress into strain energy. Meanwhile, the brittle deformation can transform the stress into frictional heat energy, and promote the metamorphism and degradation as well. It can be concluded that deformation is more important than metamorphism to the differential evolution of the ductile and brittle deformational coals.
基金supported by the National Natural Science Foundation of China (No. 41222028)the Chinese Academy of Sciences/State Administration of Foreign Experts Affairs International Partnership Program for Creative Research Teams
文摘High-resolution lithospheric structure is essential for understanding the tectonic evolution and deformation patterns of the southeastern Tibetan plateau. This is now possible due to recent advances in ambient noise and earthquake surface wave tomography, and great improvements in data coverage from dense portable array stations deployed in SE Tibet. In this review paper, I first give a brief overview of the tomographic methods from ambient noise and earthquake surface waves, and then summarize the major findings about the lithospheric structure and deformation in SE Tibet revealed by ambient noise and earthquake surface wave tomography as well as by other seismic and geophysical observations. These findings mainly include the 3-D distribution of mechanically weak zones in the mid-lower crust, lateral and vertical variations in radial and azimuthal anisotropy, possible interplay of some fault zones with crustal weak zones, and importance of strike-slip faulting on upper crustal deformation. These results suggest that integration of block extrusion in the more rigid upper-middle crust and channel flow in the more ductile mid-lower crust will be more compatible with the current geophysical observations. Finally I discuss some future perspective researches in SE Tibet, including array-based tomography, joint inversion using multiple seismic data, and integration of geodynamic modeling and seismic observations.
