Table of Content

28 November 2014, Volume 48 Issue 11 Previous Issue    Next Issue

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Field Test of Mechanical Properties of Large Diameter Concrete Jacking Pipe in Soft Soil LIU Xiang, BAI Hai-mei, CHEN Xiao-chen, CHEN Jin-jian, WANG Jian-hua 2014, 48 (11):  1503-1509.  doi: 10.16183/j.cnki.jsjtu.2014.11.001 Abstract ( 1134 )   HTML ( 757 )   PDF (501KB) ( 672 )   Save Annular reinforcing steel bar stress and pipe-soil contact pressure during pipe-jacking were monitored on the spot. The differences of the active contact pressure from the related research results were analyzed. The results show that when the pipe is pulled in the stable slurry interface which has been already formed, and since the test pipe was pulled into the tunnel bore, the distribution of contact pressure tends to be uniform and remain stable. But the contact pressure will increase suddenly when grouting, and return to normal gradually after stopping pulling. The lateral force of the pipe is also stable, though not big, mainly showing compressive stress, whose changing is controlled by pipeline axial deviation and grouting. Therefore, the pipe is in a state of eccentric compression in the test. Compared with the results of the field test, the specification is rather conservative. Besides, the active distribution of contact pressure is close to the load model developed by Lei Han, which can be used to optimize pipeline structure design. Figures and Tables | References | Related Articles | Metrics

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Behavior of Resisting Soil Behind a Circular Caisson Well with Large Jacking Force ZHU Long, XU Zhen, BAI Zhan-wei, CHEN Jin-jian, WANG Jian-hua 2014, 48 (11):  1510-1516.  doi: 10.16183/j.cnki.jsjtu.2014.11.002 Abstract ( 1100 )   HTML ( 11 )   PDF (583KB) ( 622 )   Save Analysis of soil counterforce and displacement of circular caisson pipe jacking project was made under the effect of different top edge using the site monitoring method as well as the comparative validation of distribution pattern of resistance of different open caisson using finite element numerical simulation methods. The results show that the distribution pattern of resistance of open caisson is approximated by a straight line which mutates in the depth of the caisson bottom due to the stiffness of the floor at large and reaches the maximum at the foot. The displacement of soil occurs less but as a whole under the jacking force. Simultaneously, the rationality of less than the active state was verified in the case that the soil of open caisson produces a smaller displacement under the caisson sinking back below the front wall of the active state which gives the variation of inking back soil reactions with the different distance. Figures and Tables | References | Related Articles | Metrics

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Data Model and Data Structure of Deep Excavation Considering Parameter Fusion ZHANG Bin, HUANG Zhong-hui, ZHU Yan-fei, WANG Jian-hua 2014, 48 (11):  1517-1522.  doi: 10.16183/j.cnki.jsjtu.2014.11.003 Abstract ( 809 )   HTML ( 10 )   PDF (354KB) ( 430 )   Save A data model considering parameter fusion was presented by studying the relation among the geometric, physical and mechanical parameters of different entities during excavation. Based on C++ and the object-oriented program development method, a data structure reflecting the entity class hierarchy was introduced to develop a 3D modeling and risk pre-warning software for deep excavation. By using the 3D modeling software, the geometric and mechanical model of deep excavation was unified. The software was applied to the deep excavation of the metro station at Hanzhong Road in Shanghai, and the results show that the presented data model reflects the relation among different entities well and is effective in detecting potential risks during excavation. Figures and Tables | References | Related Articles | Metrics

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Development and Application of a Triaxial Model Test System for Pile-Soil Interface WU Jun-jie, LIU Shuai-jun, CHEN Jin-jian, WANG Jian-hua 2014, 48 (11):  1523-1527,1535.  doi: 10.16183/j.cnki.jsjtu.2014.11.004 Abstract ( 759 )   HTML ( 164 )   PDF (351KB) ( 446 )   Save Unloading effect of the deep excavation would decrease the pile's bearing capacity and increase the tensile in pile shaft. A novel test system which can control the soil stress state was developed to study the pile-soil interactive behavior. In this novel system, the normal stress on the pile-soil interface is applied by the air pressure in the triaxial cell. The soil stress along the pile axis and the movement of model pile are controlled by the double piston. The pore pressure and water flow in the soil sample are adjusted by the two water cannels on the test cell. With the monitoring part of the system, the total shear force on the interface, the relative movement of the pile, and the deformation of the soil layer can be measured during tests. The triaxial interface tests show that the limit friction resistance and friction coefficient increase with the increase of the confining pressure, and the displacement of soil also increases with the increase of the confininig pressure. Figures and Tables | References | Related Articles | Metrics

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Coupled Consolidation in Unsaturated Soils Based on Random Field Theory CHENG Yan, ZHANG Lu-lu, ZHANG Lei, WANG Jian-hua 2014, 48 (11):  1528-1535.  doi: 10.16183/j.cnki.jsjtu.2014.11.005 Abstract ( 635 )   HTML ( 204 )   PDF (397KB) ( 605 )   Save Based on the random field theory, a random finite element model of coupled unsaturated consolidation in spatial random soils was established using the covariance matrix decomposition method and Monte Carlo simulation method. The effects of spatial variability of Young's modulus and saturated permeability were investigated. The results show that the mean and standard deviation of the settlement are significantly affected by the coefficient of variation of Young's modulus, and COVE. When COVE increases, the mean and standard deviation of the settlement increase, which means the uncertainty of the settlement are increased due to the spatial variability of Young's modulus. When the correlation length of Young's modulus δlnE decreases, the standard deviation of excess pore water pressure and the surface settlement decrease due to the increased spatial averaging effect. The spatial averaging effect is more significant when the thickness of soil layer is smaller than δlnE. In general, the effect of spatial variability of ks is much less significant than that of elastic modulus, which mainly affects the unsaturated consolidation in process. Figures and Tables | References | Related Articles | Metrics

Architechural Science

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Design and Research of a Detecting System for Hollowing Wall ZHOU Zhikun, YANG Song, JIN Guihua, WANG Junwei, ZHAO Yanzheng 2014, 48 (11):  1536-1540.  Abstract ( 480 )   Save Abstract： Utilizing the differences of the knocking sound between the hollowing wall and normal wall, a detecting system was designed with a wall clamping robot as its carrier. After filtering the sound signals with HPF (high pass filter) in matlab programing, the signals were processed and the characteristic parameters of the signals were obtained. After comparing the results with the parameter of the normal signal, the decision was made whether the hollowing phenomenon exists. The experiment results show that this method is easy to use with high precision, and it can replace human beings to complete dangerous tasks. References | Related Articles | Metrics

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Typhoon Wind-Field Research and Its Simulation LIAO Liheng,ZHOU Dai,MA jin,TU Jiahuang,HONG Ronghua 2014, 48 (11):  1541-1551.  Abstract ( 223 )   Save Abstract： Investigations on typhoon wind-field and the numerical simulation in recent years were summarized．Typical and actual typhoon measurement methods such as Buoy and ground stations observation， aircraft reconnaissance，radar and satellite reconnaissance were included．Several kinds of typhoon windfield simulation models and their applicability in southern China seas were fully elaborated，including simple analytical parametric wind models，steadystate dynamical models，non-steady dynamical models and kinematical models．Furthermore，prediction of extreme wind velocities based on the site in typhoon，the typhoon influence area and entire track of typhoon were mentioned in detail．Finally the development trends and some problems to be solved in this area were given. References | Related Articles | Metrics

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Numerical Simulation of Wind Pressure and Wind-Induced Dynamic Responses of an UmbrellaShaped Membrane Structure WANG Zitong,MA Ning,ZHOU Dai,SUN Yinghao 2014, 48 (11):  1562-1567.  Abstract ( 174 )   Save Abstract： By using commercial software ADINA, the numerical simulation of the wind pressures and wind-induced dynamic responses of an umbrellashaped tension membrane structure were performed. Some key effects including wind-induced dynamical displacements, velocities, accelerations and equivalent stresses of the membrane structure were systematically investigated. Moreover, the effect of several important parameters on wind pressures and structural windinduced dynamic responses was summarized, such as structural rise-span ratio, incoming wind direction, membrane initial pretension and opening/closure forms in the membrane hat. Furthermore, the structural windinduced responses and wind pressure coefficients were obtained. The present results can provide reference for the wind resistant design of similar tension membrane structures. References | Related Articles | Metrics

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Simulation of Wind Pressure Distribution and Equivalent Static Wind Loads of a Complex Longspan Dome Grid Structure Under Undulating Terrains QIAO Shuaibin1,LU Dan2,MA Ning1,ZHOU Dai1,WANG Zitong1 2014, 48 (11):  1562-1567.  Abstract ( 152 )   Save Abstract： The wind pressure distribution, wind-load shape coefficients and equivalent static wind loads of a complex longspan dome-grid structure under undulating terrains were numerically simulated using FLUENT. The results show that the distribution of wind load shape coefficients are quite different with the change of the wind direction. The time-history series of wind velocity was simulated based on the harmonic superposition method and then turned into the timehistory series of wind pressure. The FEM model of the structural system was constituted by using ANSYS and the structural wind-induced responses and wind load shape coefficients were obtained based on the timehistory series of wind-pressure. The wind-induced dynamic amplification factor was defined, so the structural resonant responses could be considered. Then, the wind-induced dynamic amplification factor was combined with the distribution of instantaneous wind pressure at the given time and the equivalent static wind loads of the structural system were established. The numerical analysis reveals the distribution of  equivalent static wind loads based on the minimum vertical reaction forces of structural system. References | Related Articles | Metrics

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Experimental Study of Bearing Behavior of Composite Foundation with Flexible Pile and Lateral Restraint at Long-term Load WU Youping1,ZHANG Keneng1,LIU Jie2,HE Jie2 2014, 48 (11):  1568-1573.  Abstract ( 109 )   Save Abstract： In order to study the bearing behavior of composite foundation with flexible pile at longterm load, comparative experiments of composite foundation with rammed soilcement pile with or without lateral restraint at longterm load were conducted. Settlement marks were laid on the surface of composite foundation to measure the sedimentation of pile and soil, from which the variation law of the sedimentation of pile and soil with time could be obtained. By laying earth pressure cells on the surface and bottom of the foundation and building PVC tube with stain gauge in pile shaft to measure the stress value, the stress variation of pile top and soil top, the stress ratio of pile soil and pile shaft tress change with time were analyzed.  The results of comparative tests show that at longterm load, the performance of composite foundation of rammed soil-cement pile with lateral constraint length piles is obviously better than that without lateral restraint, which can greatly shorten the time step in stable phase (approximately 64%) and reduce the settlement after construction (approximately 29% to 42%), and decrease the pilesoil stress ratio approximately 39%, hence adjust the distribution of axial force of pile shaft significantly. It can be acknowledged that when soft soil is treated with flexible pile, the settlement after construction can be effectively reduced and bearing capacity of subgrade can be improved if rigid long pile is set as lateral restraint. References | Related Articles | Metrics

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Fast First Order Reliability Method Based on Adaptive Step Size Parameters ZHOU Shengtong,LI Hongguang 2014, 48 (11):  1574-1579.  Abstract ( 141 )   Save Abstract： The key problem for fast first order reliability method (FORM) is to quickly find out the design point of limit state function. After analyzing some HLRFbased design point searching algorithms, a novel FORM was proposed based on the Shi-Shen line search rule. As this FORM is based on adaptive step size parameters, it is referred to as aHLRF. Compared with the traditional HLRF-based method, the aHLRF not only is globally convergent, but also can adaptively estimate some important algorithm parameters using previous iteration information. The robustness and efficiency of the aHLRF were also discussed. Examples illustrate that the aHLRF is very efficiency for estimating the first order reliability probability, especially for problems whose the nonlinearity of limit state function near the design point is very large. References | Related Articles | Metrics

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Experimental Study of Seismic Behavior of Prefabricated Reinforced Concrete Frame with Infill Slit Shear Walls JIA Bin1，ZHANG Qilin1，YANG Bin1，LV Jia1，LU Jiasen2，ZHENG Zhenpeng2 2014, 48 (11):  1580-1587.  Abstract ( 122 )   Save Abstract： In order to study the seismic performance of prefabricated reinforced concrete frame with infill slit shear walls (PRCFW), two half-scale PRCFW models with one bay, two stories were designed to conduct low cyclic load. The failure mechanism and deformation capacity of PRCFW were gained after the analysis of the failure mode, stiffness degradation, ductile behavior and performance of energy dissipation of specimens. Experimental studies show that the castin-situ joint presents good working performance during this experiment, and the seismic design requirement of strong connection-weak bar is satisfied. The PRCFW has good ductility with a ductility factor greater than 3. The failure mode of slit shear walls is changed and developed from the bending failure of shear wall into the shear failure whose shear crack runs through the whole shear wall. Besides, no failure occurs in the connection between the frame and the infill wall. Moreover, the shear connector worked well. The test results can provide useful information for further research and engineering application of PRCFW. References | Related Articles | Metrics

Chemical Industry

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Anti-Condensation Based on DesiccantCoated Metal Surface HAO Ruiying,GE Tianshu,DAI Yanjun 2014, 48 (11):  1588-1594.  Abstract ( 153 )   Save Abstract： Water vaporcondensation on metal surface causes corrosion and further affects the performance. In order to decrease this disadvantageous effect, in this paper, the coating of desiccant material (silica gel) to metal surface was proposed. The performance of this method was analyzed both by experiments and by theoretical investigation. Condensation time was adopted as the performance index. Experimental results indicate that desiccantcoated metal surface can effectively delay condensation time which is defined as parameter t. When the temperature difference between metal surface and the dew point is constant, t increases with the decrease of the dew point temperature.When the dew point temperature is constant, t increases with the increase of metal surface temperature. Then, the dynamic condensation process on metal surface was analyzed using the adsorption kinetic model. The diffusivity of water vapor is calculated, because t is affected by the diffusivity of water. The results show that the diffusivity of water vapor is affected significantly by the temperature of silica gel and the water vapor partial pressure. When the temperature of silica is constant, the water vapor diffusivity decreases with decreasing water vapor partial pressure. And when the water vapor partial pressure is constant, the water diffusivity decreases with decreasing temperature of silica, leading to a longer delay time of condensation. Key words： References | Related Articles | Metrics

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Experimental Research of Voidage of Pressurized Dense-Phase Pneumatic Conveying LU Peng1,PU Wenhao1,CHEN Xiaoping2,ZHAO Changsui2 2014, 48 (11):  1595-1599.  Abstract ( 100 )   Save Abstract： Experiments on the conveying characteristics of Inner Mongolia bituminous coal powder were conducted on a pilotscale pressurized pneumatic conveying test rig. Effects of operational conditions and material properties on the voidage ε were explored respectively. The results indicate that increasing the conveying pressure p is beneficial for conveying at a lower ε. ε initially drops and then grows with the rise in the flow rate of fluidizing gas Qf. Increase of supplemental gas Qsp leads to a higher ε. With the increase of total differential pressure Δp, ε of 52 μm coal decreases at first and then increases marginally, whereas the voidages in the riser section εr of 115 μm and 300 μm coal both rise continually. εr of pulverized coal with larger particle size exhibits a lower voidage at the same Δp. Increase of the moisture content  M of coal results in a lower volumetric flow rate of solids and a higher volidage of the two phase flow. With the decrease of superficial gas velocity Vg, the flow regime of 300 μm coal changes from suspended flow to slug flow, while the volidge in the pipeline εp declines gradually. References | Related Articles | Metrics

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Simulation Optimization of Deposition Parameters in HFCVD Diamond Films Growth on Large Quantities of Drills CHENG Lei,ZHANG Jianguo,WANG Xinchang,ZHANG Tao,SHEN Bin,SUN Fanghong 2014, 48 (11):  1600-1605.  Abstract ( 112 )   Save Abstract： Based on the finite volume method (FVM), the substrate temperature distributions in HFCVD diamond films growth on large quantities of drills with the conventional deposition parameters were investigated. The corresponding temperature measurement tests were also conducted, verifying the rationality and correctness of the simulation method and results. Based on the traditional equidistant filament arrangement, the influences of different deposition parameters on substrate temperature distributions were systematically studied, including the filament separation D, filament length L, filament radius r, filament temperature T and filament height H. Furthermore, a novel nonequidistant filament arrangement was proposed to further improve the uniformity of the substrate temperature distribution, and the optimized deposition parameters were finally determined. The diamond coated drills fabricated with such optimized parameters present satisfying uniformity coating quality, further testifying the reliability of the parameters optimization method based on the simulations. References | Related Articles | Metrics

Mathematical sciences and chemical

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Flow Field Characteristics of Hydrodynamic Polishing Base Plate with Different Structural Flow Passages LI Gang,ZHANG Li,WEN Donghui 2014, 48 (11):  1606-1612.  Abstract ( 119 )   Save Abstract： Three types of structural flow passages were designed, and flow field characteristics of hydrodynamic polishing base plates in different structure flow passages were studied. A mathematical model of flow field with constraint condition were built based on the liquid dynamic theory, and Matlab was used to compare and analyze the distributions of liquid dynamic pressure at different structural parameters. Relationships between buoyancy and film thickness, pressure distribution, structural parameters were obtained. Fluent software was used to calculate the pressure and speed distribution of flow fields. Theoretical and numerical results show that the largest buoyancy is produced by the parabolic structure flow passage，followed by the wedge structure flow passage, while the L structure flow passage is produces the smallest buoyancy. The flow velocity is relatively stable in the area where the workpiece is adhered, providing good condition for noncontact polishing process. References | Related Articles | Metrics

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Modification of Chitosan and Free Radical Scavenging Activities ZHOU Yuanjing1,XU Qing2,ZHAO Hongxia3,GAO Guilong4 2014, 48 (11):  1613-1620.  Abstract ( 145 )   Save Abstract： Chitosan and its derivatives are unique cationic copolymer of glucosamine and Nacetylglucosamine. They have drawn much attention in various fields, including pharmaceutical, biomedicine, water treatment, cosmetics, agriculture, and food industry, due to their useful characteristics such as biorenewabilty, biodegradability, biocompatibility, bioadhesivity and nontoxicity. This paper introduced the synthetic method of different molecular weight, different degree of deacetylation and Omodified chitosan. Moreover, it revewed the recent free radical scavenging activities of chitosan and its derivatives and discussed in brief the roles molecular weight, degree of deacetylation and Omodification played in free radical scavenging. References | Related Articles | Metrics

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Numerical Study of Wave-Induced Dynamic Soil Response and Liquefaction ZHANG Jun, ZHOU Xiang-lian, YAN Yu-guang, GUO Jun-jie, WANG Jian-hua, JIANG Jun-da 2014, 48 (11):  1621-1626.  doi: 10.16183/j.cnki.jsjtu.2014.11.018 Abstract ( 815 )   HTML ( 396 )   PDF (326KB) ( 805 )   Save In this paper, based on Biot's theory, a numerical model for wave-seabed-pipeline dynamic response was established to investigate seabed instability failure. The seabed was treated as porous medium. The model simulated the distribution of pore pressure and effective stress, and the process of liquefaction around buried pipeline under various wave loads were investigated. Partly dynamic (u-p) formulations for the wave-induced response of the seabed with pipeline were adopted. In partly dynamic analysis, the u-p formulation in which both displacement and pore pressure were field variables was adopted considering the acceleration of soil skeleton while neglecting the inertial terms associated with pore water. Using COMSOL Multiphysics, a parametric study, including the permeability, degree of saturation, buried depth and wave height was conducted to investigate the seabed response. Then, a criterion for liquefied state was used and the possibility of wave-induced liquefaction occurring in porous seabed was studied. Figures and Tables | References | Related Articles | Metrics

Astronomy,Geoscience

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Parallel Resampling Method of Remote Sensing Data Based on Pre-Partitioning for Cloud Computing CHI Ziwena,b,ZHANG Fenga,b,DU Zhenhonga,b,LIU Renyia,b 2014, 48 (11):  1627-1632.  Abstract ( 111 )   Save Abstract： In order to solve the problem of parallel resampling of remote sensing image data in cloud computing, which is the basis for rapid publication of massive remote sensing image date, a parallel resampling method of remote sensing data based on prepartitioning was proposed in combination with the features of MapReduce parallel computing and the characteristics of remote sensing image data processing. Through the prepartitioning mechanism, the image data splitting and parallel resampling tasks can be effectively controlled, and the problem of MapReduce framework application in the unstructured remote sensing data with spatial location features processing was solved, thereby, the efficient parallel resampling of remote sensing image data in cloud computing environment is implemented. In the experiment, a parallel resampling flow on the opensource Hadoop platform was designed according to the parallel resampling method of remote sensing data based on prepartitioning. The experiment and analysis show that the parallel resampling method has a good resampling performance and is capable of achieving the efficient resampling of high resolution remote sensing image data in cloud computing environment. References | Related Articles | Metrics

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Numerical Analysis of Leg Mating Unit Test Model ZHENG Yikan1,ZHANG Shilian1,CANG Xin2 2014, 48 (11):  1633-1638.  Abstract ( 135 )   Save Abstract： In this paper, numerical analysis of a domestically developed leg mating unit (LMU) test model was conducted using nonlinear FEM. The characteristics of the loaddisplacement relationship and stress distribution were discussed. The stress and displacement in the measurement points were compared with the model test results. The comparison indicates that the results of nonlinear FEM agree well with the model test. As a consequence, nonlinear FEM can be applied in the design and development of LMU. The method and the conclusion can provide reference for the design and analysis of LMU. References | Related Articles | Metrics

Atomic Energy Technology

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Fatigue Crack Growth of Alloy 690 Tubing CHEN Kai 1，DU Donghai1，LU Hui1，ZHANG Lefu1,SHI Xiuqiang2，XU Xuelian2 2014, 48 (11):  1639-1643.  Abstract ( 77 )   Save Abstract： Fatigue crack growth rate (FCGR) data of three kinds of alloy 690 by different manufacturing process were generated in air at room temperature and 325 ℃ using the pin-loading tension (PLT) specimen and direct current potential drop (DCPD) method. The testing data were modeled with the Paris-Erdogan equation, and a linear relation between log(da/dt) and log(ΔK) was observed, which indicated good veracity and reliability of results. The threshold stress intensity factor amplitude ΔKth of the three alloys was predicted from the fatigue crack growth curve at 325 ℃, and material B has the highest ΔKth, showing best fatigue resistance performance. Scanning electron microscopy (SEM) examination of the fatigue fracture surfaces revealed transgranular attack, and the transgranular regions of the fatigue fracture surface were covered with striationlike features, indicative of micro-plastic deformantion. References | Related Articles | Metrics

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SCC Crack Growth Rate Dependence of Cold Worked 316L Stainless Steel on Dissolved Oxygen in High Temperature Water DU Donghai1，LU Hui1，CHEN Kai1，ZHANG Lefu1,SHI Xiuqiang2，XU Xuelian2 2014, 48 (11):  1644-1649.  Abstract ( 62 )   Save Abstract： The cold bent 316L pipe was used to study the dependence of crack growth rate on dissolved oxygen in simulated temperature and pressure of primary side water environment. The crack growth rates were measured insitu realtime using the direct current potential drop method. Experimental results indicate that the crack growth rates increase with the increase of dissolved oxygen. When the oxygen content is less than 0.2 mg/L, the increase of the crack growth rate is very significant, while above this value, it becomes unconspicuous. This result was compared with those of other researchers’ and possible reasons were analyzed. References | Related Articles | Metrics

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Application of SolutionDiffusion Model in Removal of Cobalt Ions by Reverse Osmosis YUE Zhidong，KUAI Linping 2014, 48 (11):  1650-1654.  Abstract ( 99 )   Save Abstract： The solution-diffusion model was used to predict the behavior of reverse osmosis membrane,when used for the removal of cobalt from radioactive wastewater.System mass balances together with solutiondiffusionmass transfer models were used to simulate the separation process of low concentrations of cobalt.Model equation constants were obtained when the cobalt concentration was high, and  the experimental data were then compared with simulated data when the cobalt concentration was low. The results show that the relative error between experimental data and simulated data does not exceed 15%. Good agreement between the experimental and the predicted cobalt concentrations suggests that the solutiondiffusion model can be used to well predict osmotic concentration even when the concentration of cobalt is low. Key words： References | Related Articles | Metrics

Others

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Establishment and Analysis of Artificial Neural Network Distributed Model for Sea Wall Osmosis Pressure HUANG Ming1,LIU Jun2 2014, 48 (11):  1655-1659.  Abstract ( 153 )   Save Abstract： In order to describe the distributed character of sea wall osmosis pressure  and analyze its rule under special coastal condition, artificial neural network was considered with multiple survey point information. Coordinates of survey points were added to input layer together with former tidewater factor, integral rain factor and time effect factor. The monitored data were used to train the distributed model. Based on the training result, complementary coordinate samples were put into the model, and osmosis pressure of different locations and distributed curve were obtained. The general regression neural network was used, taking the monitored information of Pudong sea wall as instances. The instances illustrated the establishment of distributed model and the obtainment of distributed curve, although the neural network does not give apparent expressions. Moreover, sea wall osmosis pressure special distributed rules were analyzed using these results. References | Related Articles | Metrics

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Lyapunov Characteristic Exponents and Dynamic Elastic Instability of Steel Liquid Storage Tanks YANG Hongkang1,2,GAO Boqing1 2014, 48 (11):  1660-1666.  Abstract ( 88 )   Save Abstract： To comprehensively evaluate the dynamic stability of liquid storage tanks under earthquake excitations, the equivalent dynamic perturbation equations were established based on coupled fluidsolid model with displacementpressure form, the resistance force in structure domain was parameterized by timevarying geometric stiffening matrix, the generalized perturbation variables were then modified and the vector length was adjusted in real-time, and the dynamic Lyapunov characteristic exponents were then solved with time-stepping techniques, by which the dynamic stability analysis of a 100 000 m3 oil storage tank was respectively executed under harmonic and earthquake ground motions. The results show that the dynamic instability regions obtained by the above Lyapunov method were essentially consistent with the estimates of Floquet method, and the maximum relative error of critical peak ground acceleration calculated by Lyapunov method and B-R criteria method is appoximately 10 %, and the wind girders are helpful to inhibit dynamic instability regions and improve the critical peak ground acceleration. The proposed Lyapunov method is suitable for secondorder dynamic systems, can consider the effect of earthquake duration, and does not restrict the characteristics of seismic waves. Moreover it also dramatically reduces the computing cost of dynamic stability analysis and meets the precision requirement for engineering application. References | Related Articles | Metrics