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| 1 | Numerical modeling of concrete hydraulic fracturing with extended finite element method显示文摘The extended finite element method (XFEM) is a new numerical method for modeling discontinuity. Research about numerical modeling for concrete hydraulic fracturing by XFEM is explored. By building the virtual work principle of the fracture problem considering water pressure on the crack surface, the governing equations of XFEM for hydraulic fracture modeling are derived. Implementation of the XFEM for hydraulic fracturing is presented. Finally, the method is verified by two examples and the advan- tages of the XFEM for hydraulic fracturing analysis are displayed. | REN QingWen DONG YuWen YU TianTang | 2009 | Science China(Technological Sciences)2009，52，3： | 29 |
| 2 | Research advance in safety analysis methods for high concrete dam显示文摘High tensile stresses occurred in high concrete dams and in their foundation lead to the growing importance of their safety with the increase of concrete dam height. Without any exiting specification or successful experiences of concrete dams up to 300 m at home and abroad for reference, experts feel obliged to figure out how to perform safety analysis on high concrete dam. This paper involves the main contents and mechanical features of the safety analysis on high concrete dam and shows the current state and progress of the analysis methods. For the insufficiency and problems existing in normative methods, study on modern numerical method such as finite element method must be strengthened to find out the stress control criterion which is in accordance with the methods. Two aspects of the safety analysis of high dam—— local damage from material level and integral destruction from structure level——should be considered. For the local damage, we should consider the non-homogeneity of material and strengthen the research of meso-damage mechanics. While for integral destruction of the system of high dam and its foundation, a study on non-strength theory should receive enough concerns. Further, attention should be paid to the research on the failure modes and criterions of high concrete dam failure analysis and safety evaluation, and the effect of uncertainty and classification of safety should be considered too. | REN QingWen XU LanYu WAN YunHui | 2007 | Science China(Technological Sciences)2007，50，z1： | 12 |
| 3 | Dynamic response of gravity dam model with crack and damage detection显示文摘Gravity dam is a typical structure that has been frequently used in the fields of water conservancy engineering, and the safety of the structure has received widespread attention recently. Due to earthquakes or other reasons, gravity dams normally have damage such as cracks in practical service. Damage in the structures can alter the structural dynamic behavior and seriously affect structural performance. Maintaining safety and integrity of the gravity dam structures requires a better understanding of dynamic response of structure with damage and associated damage detection method. In order to study thoroughly the dynamic behavior of gravity dam with damage, the sweep vibration responses of the gravity dam with and without damage are investigated. The experimental results show that the peak-peak acceleration responses all increase for the structure is with crack. At the same time, a structural damage detection method, i.e., the local damage factor (LDF) method, is considered in the study of gravity dam damage detection when the dam is subjected to the base excitation. It is shown that the LDF method can be used as a damage index and is capable of evaluating both the presence and relative severity of structural damage, and it can be used as a viable condition assessment and damage identification technique to detect and quantify the damage in the gravity dam. | WANG ShanShan REN QingWen | 2011 | Science China(Technological Sciences)2011，54，3： | 8 |
| 4 | Experimental research and numerical simulation of RC beams strengthened with bonded steel plates显示文摘It is a common method to strengthen the damaged RC structures with bonded steel plates. At present the ultimate bearing ca- pacity of RC structures strengthened with bonded steel plates is calculated mostly using the theory based on the test. Four beams, including one reference beam, two strengthened concrete beams in primary force and secondary force respectively, and one strengthened concrete beam which was not anchored enough, were tested under four-point bending (4PB) in order to get the data of strain of longitudinal bars, bonded bottom steel plate in tension and deflection of beams in the middle span. The experimental program was supported by a three-dimensioned finite analysis using ABAQUS. At the end of experiments and finite analysis, it is concluded that the investing strengthening technique can significantly improve the load-carrying capacity and the phenomenon of stress concentration at the end of interface, as well as the damage at interface, can be well simulated with cohesive element provided by ABAQUS. | LEI Dong CHEN GuangYuan CHEN YuQuan REN QingWen | 2012 | Science China(Technological Sciences)2012，55，12： | 8 |
| 5 | Relationship between local damage and structural dynamic behavior显示文摘Damage in the structures alters the structural dynamic behavior. Damage generally occurs locally in the components of structures, and its effect often exhibits in the changes of both local and global characteristics of structures. Better understanding of this relationship helps to monitor and assess the condition of structures and develop dynamics-based structural health monitoring techniques. In this study, the relationship between the local damage and structural dynamic behavior is investigated. To validate the concept, an experiment of a three-dimensional (3-D) steel frame structure with different magnitudes of local damage is illustrated. The experimental results indicate that the change of global resonant response between the intact and damage structure is not obvious. The change of local resonant responses measured near the location of saw-cut crack damage is quite significant. The experimental study conducted indicates that the local resonant responses at the low order resonance can be used as an effective damage identification method to detect and quantify the local damage in the 3D frame structures. | WANG ShanShan REN QingWen | 2012 | Science China(Technological Sciences)2012，55，12： | 7 |
| 6 | Definition of the general initial water penetration fracture criterion for concrete and its engineering application显示文摘A general initial water penetration(seepage) fracture criterion for concrete is proposed to predict whether or not harmful water penetration(hydraulic fracturing),other than microcracking,will occur in concrete structures in a severe high water pressure environment.The final regression,of the different macroscopic failure types in concrete to microscopic ModeⅠ c racking,allows the use of only one universal criterion to indicate the damage.Thus,a general initial water penetration fracture criterion is approximately defined as a strain magnitude of 1000×10-6,based on the concept of tensile strain derived from experimental results in the relevant literature.Then,the locations of harmful water penetration fracture(hydraulic fracture) in the high arch dam mass of the Jinping first class hydropower project are analyzed using the nonlinear finite element method(FEM) according to the proposed criterion.The proposed criterion also holds promise for other concrete structures in high water pressure environments. | JIANG YaZhou REN QingWen XU Wei LIU Shuang | 2011 | Science China(Technological Sciences)2011，54，6： | 6 |
| 7 | Characteristics of Fe-based WC Composite Coatings Prepared by Double-pass Plasma Cladding Process显示文摘The Fe-based WC composite coatings were clad on Q235 steel by double-pass plasma cladding method,in which the WC-Co(WC covered with cobalt:78wt%WC,12wt%Co)doping was about 10wt%,20wt%and 40wt%,respectively.The microstructure and wear performance of the composite coatings were investigated by X-ray diffraction(XRD),scanning electron microscope(SEM),energy dispersive spectrometer(EDS)and ball-disc wear tests.The results show that the clad coatings contain mainly?-Fe,WC and carbides(Cr23C6,Fe3W3C-Fe4W2C)phases and the precipitation of carbides increases with the increase of WC-Co doping content.The WC-Co doping content has an obvious effect on the microstructure of the clad coatings.For the clad coatings with low WC-Co doping,the microstructure gradually transforms from planar crystal at the interface of substrate/coating to cell/dendritic crystal at the middle and the upper portion of the coatings.But there are a number of fishbone-like structure at the middle and the upper portion of clad coating with 40wt%WC-Co doping.The microstructure at the top is smaller than that at the bottom for all the coatings.The maximum of hardness of the clad coatings is 72.3HRC which is about 6.9 as much as the hardness of Q235 steel substrate.The composite coatings have good wear resistance due to the reinforcement of carbide particles and the strong bonding between carbide particles and ferroalloy.The suitable increase of WC-Co doping content can improve the wear resistance of the composite coatings. | Jiang Shaoqun Ren Qingwen Ying, Ding Gang, Wang Yu, Yi Wang Zehua Zhou Zehua | 2012 | 稀有金属材料与工程2012，41，S1： | 6 |
| 8 | Study on the performance of arch dam influenced by relaxation of the foundations following excavation显示文摘This paper studies the influence of a stress relaxation zone caused by foundation excavation on the performance of Jinping-I arch dam, using the orthogonal experiment method. Firstly, by adopting the characteristic stress of the dam as an index and coupling it with range analysis, the most significant factors and the degree of relaxation influence on the arch dam performance are found. This is then combined with monitoring data from the dam, and the extent of influence on the arch dam performance caused by the relaxation is evaluated through numerical analysis. The results show that the relaxation of foundation excavation has a negative impact on the performance of the arch dam in general, the extent of elastic modulus degradation in the relaxation zone being the main factor affecting stresses in the dam. The relaxation of the rock mass leads to an increase in dam stress in local areas near the relaxation zone, but has little effect on more distant areas. | DUAN ShaoHui REN QingWen CHEN JunPeng LI Qiang | 2011 | Science China(Technological Sciences)2011，54，5： | 5 |
| 9 | Research advance in failure risk and local strength failure for high arch dams显示文摘To develop national economy and use the water resources and hydropower resources sufficiently,a lot of high arch dams,with the height of more than 200 m,have been and will be built in China.Although arch dams have good mechanical behavior,there is still failure possibility due to the huge water pressure and high stress level in dam,complex topographic and geologic conditions,formidable environment and high intensity earthquake.As one of the three main aspects concerning the safety of high arch dam,the study on global destruction,has been elaborated in the literatures,and research advance in the other two aspects,namely the failure risk and local damage of high arch dams,will be reviewed in this paper.In recent years,the failure risk of high arch dams has been investigated,and the model for identifying dam failure risk factors has been established.It is shown that the foundation deterioration and strong earthquake are the major risk sources for high dam failure.With the fault tree method,the failure mode and failure probability of high arch dams are studied,and the principle for determining failure mode and the method of calculating failure probability are proposed.Meanwhile,the determination principle of acceptable risk standard for high arch dam was proposed,and the acceptable risk rate and the acceptable standard value of various risk losses were given.For the local damage of arch dam,it is pointed out that the local damage belongs to the strength failure at material level.The study on local failure mechanism of arch dam is reviewed,based on the theories that from traditional strength theory to damage mechanics and meso-mechanics theory.Aiming at the cracking,the main pattern of local failure of high concrete dam,the research advances in the analysis methods and cracking criteria for smeared crack model and discrete crack model are summarized,and the research findings of preventive measures for local failure are shown. | REN QingWen LI Qiang LIU Shuang | 2012 | Chinese Science Bulletin2012，57，36： | 5 |
| 10 | Ultimate bearing capacity of concrete dam involved in geometric and material nonlinearity显示文摘To get the actual ultimate bearing capacity of concrete dam, the effect of geometric nonlinearity and strain softening on it, which appears in the failure process of concrete dam, is studied. Overload method is adopted to obtain the bearing capacity of a concrete dam by taking into consideration strain softening in the material constitutive law, geometric nonlinearity in geometric equation and equilibrium differential equation. Arc-length method is used to find the extreme point and descending branch of the load-displacement curve of the dam. The results present that the effect cannot be ignored. And geometric nonlinearity of structure and strain softening of materials should be considered for numerical analysis of ultimate bearing capacity of a concrete dam. | REN QingWen JIANG YaZhou | 2011 | Science China(Technological Sciences)2011，54，3： | 4 |
| 11 | Simulated NH_4^+-N Deposition Inhibits CH_4 Uptake and Promotes N_2O Emission in the Meadow Steppe of Inner Mongolia, China显示文摘Few studies are conducted to quantify the effects of enhanced N deposition on soil nitrous oxide(N_2O) emission and methane(CH_4) uptake in the meadow steppe of Inner Mongolia, China. A two-year field experiment was conducted to assess the effects of nitrogen(N) deposition rates(0, 10, and 20 kg N ha^(-1)year^(-1) as(NH_4)2SO_4) on soil N_2O and CH_4 fluxes. The seasonal and diurnal variations of soil N_2O and CH_4 fluxes were determined using the static chamber-gas chromatography method during the two growing seasons of 2008 and 2009. Soil temperature, moisture and mineral N(NH_4^+-N and NO-3-N) concentration were simultaneously measured. Results showed that low level of(NH_4)2SO_4(10 kg N ha-1year-1) did not significantly affect soil CH_4 and N_2O fluxes and other variables. High level of(NH_4)_2SO_4(20 kg N ha^(-1)year) significantly increased soil NO-3-N concentration by 24.1% to35.6%, decreased soil CH_4 uptake by an average of 20.1%, and significantly promoted soil N_2O emission by an average of 98.2%.Soil N_2O emission responded more strongly to the added N compared to CH_4 uptake. However, soil CH_4 fluxes were mainly driven by soil moisture, followed by soil NO-3-N concentration. Soil N_2O fluxes were mainly driven by soil temperature, followed by soil moisture. Soil inorganic N availability was a key integrator of soil CH_4 uptake and N_2O emission. These results suggest that the changes of availability of inorganic N induced by the increased N deposition in soil may affect the CH_4 and N_2O fluxes in the cold semi-arid meadow steppe over the short term. | LIU Xingren ZHANG Qingwen LI Shenggong ZHANG Leiming REN Jianqiang | 2017 | Pedosphere2017，27，2： | 4 |
| 12 | Theory and methods of global stability analysis for high arch dam显示文摘The global stability of high arch dam is one of the key problems in the safety study of arch dams,but no feasible method with theoretical basis is available.In this paper,based on the stability theory of mechanical system,it is demonstrated that the global failure of high arch dams belongs to a physical instability starting from local strength failure,which is the extreme point instability according to the characteristics of load-displacement curve obtained from the failure process of dam-foundation system. So the global failure of dam-foundation system should be studied with the stability theory of mechanical system.It is also pointed out that the current stability analysis methods used in engineering are consistent with the stability theory,but not established according to the mechanical system stability theory directly.A perfect method can be obtained through the study of physical disturbance equations. | REN QingWen 1,LI Qiang 1,JIANG YaZhou 2 & JIANG XiaoLan 3 1 Department of Engineering Mechanics,Hohai University,Nanjing 210098,China 2 College of Water Conservation and Hydropower Engineering,Hohai University,Nanjing 210098,China 3 Changjiang Academy of Sciences,Wuhan 430010,China | 2011 | Science China(Technological Sciences)2011，54，S1： | 3 |
| 13 | Modeling crack in viscoelastic media using the extended finite element method显示文摘In this paper,the problem of modeling crack in 2D viscoelastic media is studied using the extended finite element method.The paper focuses on the definition of enrichment functions suitable for cracks assessment in viscoelastic media and the generalized domain integrals used in the determination of crack tip parameters.The opening mode and mixed mode solutions of crack tip fracture problems in viscoelastic media are also undertaken.The results obtained by the proposed method show good agreement with the analytical methods and provide reasonable background information to enhance the modeling of crack growth in viscoelastic media. | YU TianTang REN QingWen | 2011 | Science China(Technological Sciences)2011，54，6： | 2 |
| 14 | A continuum model of jointed rock masses based on micromechanics and its integration algorithm显示文摘The paper is devoted to proposing a constitutive model based on micromechanics. The joints in rock masses are treated as penny-shaped inclusion in solid but not through structural planes by considering joint density, closure effect, joint geometry. The mechanical behavior of the joints is represented by an elasto-plastic constitutive law. Mori-Tanaka method is used to derive the relationship between the joint deformations and macroscopic strains. The incremental stress-strain relationship of rock masses is formulated by taking the volume average of the representative volume element. Meanwhile, the behavior of joints is obtained. By using implicit integration algorithms, the consistent tangent moduli are proposed and the method of updating stresses and joint displacements is presented. Some examples are calculated by ABAQUS user defined material subroutine based on this model. | ZHU FuWei DUI GuanSuo REN QingWen | 2011 | Science China(Technological Sciences)2011，54，3： | 2 |
| 15 | Molecularly Imprinted Polymer Thin Film Based Surface Plasmon Resonance Sensor to Detect Hemoglobin显示文摘 | WANG Yang ZHANG Qingwen REN Yamin JING Lijing WEI Tianxin | 2014 | Chemical Research in Chinese Universities2014，30，1： | 2 |
| 16 | Structural damage detection using local damage factor显示文摘 | Shanshan Wang Qingwen Ren Pizhong Qiao | 2006 | Journal of Vibration and Control2006，12，9： | 1 |
| 17 | Primary gout inShantou: a clinical and epidemiological study显示文摘 | ZENG Qingyu WANG Qingwen CHEN Ren | 2003 | Chin Med J2003，116，1： | 1 |
| 18 | Research on determining solid structure critical load and failure mode 显示文摘 | LI Qiang REN Qingwen | 2013 | Engineering Failure Analysis2013，，： | 1 |
| 19 | Anchoring Bolt Detection Based on Morphological Filtering and Variational Modal Decomposition显示文摘The pull test is a damaging detection method that fails to measure the actual length of a bolt.Thus,the ultrasonic echo is an important non?destructive testing method for bolt quality detection.In this research,the variational modal decomposition(VMD)method is introduced into the bolt detection signal analysis.On the basis of morphological filtering(MF)and the VMD method,a VMD?combined MF principle is established into a bolt detection signal analysis method(MF?VMD).MF?VMD is used to analyze the vibration and actual bolt detection signals of the simulation.Results show that MF?VMD effectively separates intrinsic mode function,even under strong interference.In comparison with conventional VMD method,the proposed method can remove noise interference.An intrinsic mode function of the field detection signal can be effectively identified by reflecting the signal at the bottom of the bolt. | XU Juncai REN Qingwen LEI Bangjun | 2019 | Transactions of Nanjing University of Aeronautics and Astronautics2019，36，4： | 1 |
| 20 | Nonde-structive assessment of reinforced concrete structuresbased on fractal damage characteristic factors显示文摘 | Cao Maosen Ren Qingwen Qiao Pizhong | 2006 | Journal of Engineering Mechanics2006，132，9： | 1 |
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