西南交通大学学报

Analysis of Effect of Cross Adit on Train-Tunnel Aerodynamic Multiple Peak Characteristics

WANG Yingxue, REN Wenqiang, LUO Yang, HE Jun

2018, 53(3): 427-433. doi: 10.3969/j.issn.0258-2724.2018.03.001

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Abstract:
For research the effect of setting cross adit to compression wave transmission characteristic, A cross adit near the tunnel entrance relieves the peak of a micro-compression wave; additionally, it also affects the transmission characteristics of the compression wave. In this study, on the basis of the transmission and reflection theory of compression waves, created when a high-speed train enters the tunnel, at the cross point of a tunnel and an adit, the effect of a cross adit on compression wave transmission characteristics was analysed using a three-dimensional model. Furthermore, various cross adit positions were compared in terms of their efficiency in relieving micro-compression waves. The research results showed that when the train enters approximately 10 m into the tunnel, the peak value of the first wave pressure gradient is attained. With increasing distance between the cross adit and tunnel entrance, the peak value of the pressure gradient of the second wave, created when the train passes the cross adit, decreases slightly. When the distance between the cross adit position and the tunnel entrance is changed from 20 m to 50 m, the pressure gradient peak value decreases by up to 50%.

Prediction of Rock Bursts for Sangzhuling Tunnel Located on Lhasa-Nyingchi Railway Under Coupled Thermo-Mechanical Effects

YAN Jian, HE Chuan, WANG Bo, MENG Wei, YANG Junfeng

2018, 53(3): 434-441. doi: 10.3969/j.issn.0258-2724.2018.03.002

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Coupled thermo-mechanical effects on the prediction of rock bursts for tunnels with special geostress and high geotemperatures is a new problem that needs to be solved. During the excavation of the newly built Sangzhuling tunnel in the Lhasa-Nyingchi railway project, the geotemperature at different buried depths was obtained by field temperature test data inversion. The gradually changing hole stress during the excavation process was clarified by coupled thermo-mechanical numerical simulation. The range and intensity of rock bursts throughout the entire calculation scope of a typical section under various stress-relieving coefficients and geotemperature conditions, combined with different of rock burst criteria, such as Russense, TAO Zhenyu, WANG Yuanhan, and FAN Jianping criteria, were predicted. Finally, the prediction results were compared with the field measurements. The results show that the geothermal gradient of Sangzhuling tunnel is 5.5℃/100 m. As the buried depth of the tunnel increases, so does the geotemperature. The maximum compressive stress is concentrated in the vault and the arch springing in the deep-buried tunnel section with the gravity stress field. At 45-85℃, the maximum tangential and principal stresses increase linearly with an increase in the stress-relieving coefficient, and the maximum tangential and principal stresses increase by 84-96 MPa and 93-96 MPa, respectively, when the stress-relieving coefficient reaches 100%; the intensity of rock bursts will increase under these conditions. The analysis using the four methods for predicting rock bursts compared with rock burst data from results in field tests shows that the occurrence of rock bursts will be accelerated during stress release by coupled thermo-mechanical effects. The prediction of middle level and greater intensity rock bursts using the TAO Zhenyu criterion shows great sensitivity for the earlier stages of stress release. In the mid-late periods of stress release, the rock bursts prediction results using the WANG Yuanhan criterion are in accordance with the measured results.

Refined Simulation Analysis of Water Pressure of Tunnel Lining Based on Temperature Analogy Method

QIU Yue, HE Chuan, HE Cong, ZOU Yulin, HU Wei

2018, 53(3): 442-449. doi: 10.3969/j.issn.0258-2724.2018.03.003

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In this study, the distribution of a lining's water pressure is calculated under different construction states including excavation, lining construction, and grouting to verify the accuracy and feasibility of the temperature analogy method in water pressure calculations. The results were compared with those of the theoretical analytical method and fluid-structure coupled method. Subsequently, the distribution of the lining's water pressure on transverse and longitudinal section was numerically explored through a refined model that includes a drainage system of a double lane highway tunnel. The results indicate that the water pressure of the lining significantly increases after lining construction and that a grouting circle can effectively reduce water pressure. The longitudinal distribution presents the characters of periodic variation above the longitudinal drain pipe, maximum water pressure occurs in the centre of two annular drain pipes, and minimum water pressure occurs in annular drain pipes. The transverse distribution presents an inverted gourd shape, minimum water pressure occurs in the arch foot, and maximum water pressure occurs in the vault and invert. Under the given computational assumptions, the maximum error between the temperature analogy method and theoretical analytical method is 0.3%, and the maximum error between the temperature analogy method and fluid-structure coupled method is 14.8%. Hence, the calculation precision satisfies the required engineering accuracy.

Vibration Reduction Effect of Stepped V-Cut Blasting

ZOU Xinkuan, ZHANG Jichun, PAN Qiang, WANG Wei

2018, 53(3): 450-458. doi: 10.3969/j.issn.0258-2724.2018.03.004

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The aim of this research is to study the vibration reduction effect of stepped V-cut blasting (SV-cut) in tunnel blasting. Firstly, the method for determining SV-cut blasting parameters are provided based on the rock millisecond blasting theory. Secondly, numerical computation models for both traditional vertical V-cut blasting (V-cut) and SV-cut blasting are established using the explicit dynamic finite element program LS-DYNA^3D. Finally, combined with numerical simulation results and engineering practice, in-situ contrast blasting experiments and vibration tests using both V-cut and SV-cut blasting were performed. The results of the study indicate that the peak Von Mises stress and compression damage range at the bottom of the cut cavity for SV-cut blasting are 1.64 times and 1.66 times larger than that for V-cut blasting, respectively, which results in a more complete cut cavity with SV-cut blasting. At the top and back side of the model, the vibration reduction effectiveness of SV-cut blasting is up to 11.53% and 22.45%, respectively; however, the vibration reduction effectiveness is only 0.21% at the lateral side. SV-cut blasting can not only enable perfect blasting drivage but can also reduce the vibration intensity induced by cut hole blasting by at least 30%.

Spatial Distribution Characteristics of Rail Vibration Acceleration under Train Load

CAI Xiaopei, TAN Xi, GUO Liangwu, ZHONG Yanglong

2018, 53(3): 459-466. doi: 10.3969/j.issn.0258-2724.2018.03.005

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A vehicle-track dynamic model and track-substructure finite element model were established to study the basic parameters and sensitive areas of rail vibration, respectively, when a train passes. The models were developed based on the co-simulation of MBS software GENSYS and finite element software ABAQUS. The wheel-rail forces from the vehicle-track model were used as the excitation source in the track-substructure model, and the effects of train speed, track irregularity, and different types of track supports on rail acceleration were analyzed. The research results show that rail acceleration decays from the head to the foot of a rail, and the acceleration of the rail head above the sleepers is significantly greater than that between the sleepers. The acceleration of the rail head is sensitive to speed. For a ballastless track, as the traveling speed increases from 200 km/h to 350 km/h, the rail head acceleration increases from 1.476 km/s² to 2.980 km/s². The rail acceleration of a continuously supported ballastless track is less than that of the traditional, discrete supported ballastless track. The installation of acceleration sensors outside the rail head is recommended. The frequency and range selection of the sensor should be made taking into consideration the train speed, track irregularity, and other factors.

Collaborative Analysis of Dispatch Systems between High-Speed and Conventional Rail

ZHUANG He, LI Wenxin, YIN Yong, ZHANG Yongxiang, WEN Chao

2018, 53(3): 467-473. doi: 10.3969/j.issn.0258-2724.2018.03.006

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To ensure the efficiency and safety of trains in the railway network, an evaluation index system and a method for the collaborative analysis of dispatch systems between high-speed and conventional rail based on planned and actual railway timetable data is proposed. First, the daily coordination relationship between high-speed and conventional rail by studying the dispatch process of cross-line trains at the connect station was systematically analysed. Second, a synergetic theory was utilized to analyse the collaborative relationship between the two systems during daily operations, based on which a collaborative evaluation index system was constructed. Finally, a collaborative evaluation model between high-speed and conventional rail was established to perform a quantitative analysis on the degree of collaborative cooperation between the two systems based on a harmonious matrix. The results show that the collaborative degree between the two systems is 0.975 and efficiency as well as effectiveness of the operation at the connect station are the key factors that influence the collaborative relationship between these two dispatch systems.

Design of Inductively Coupled Power Transfer System Based on Dual-Loop Control

GONG Ming, LI Qiang

2018, 53(3): 474-482. doi: 10.3969/j.issn.0258-2724.2018.03.007

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To solve the problem of constant voltage output due to frequent load fluctuations in rail transit power supply systems, a dual-loop control strategy based on sliding mode control and PI control is proposed. First, the authors established a model for the system with a discrete time dynamic model for the primary side, and a large signal model for the secondary side. Second, a dual-loop control strategy based on the model is proposed, in which the internal current loop is controlled by sliding mode control and the external voltage loop is controlled by the PI controller. The test results show that when switching the resistance to between 70 Ω and 50 Ω under a constant output voltage, the voltage changes by about 5% and returns to a stable value in approximately 15 ms. Therefore, the proposed control strategy can ensure a constant output voltage and fast response times under frequent load fluctuations.

Effect of Ground Motion Spatial Variations on Pounding Response of High-Pier Railway Bridge

KANG Rui, ZHENG Kaifeng, LI Xi, JIA Hongyu, ZHENG Shixiong

2018, 53(3): 483-491, 499. doi: 10.3969/j.issn.0258-2724.2018.03.008

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The authors present a theoretical analysis for a typical HPRB under synchronous and asynchronous excitations, using nonlinear dynamic analysis based on OpenSees, to investigate the effect of ground motion spatial variations (GMSVs) on the pounding response of high-pier railway bridges (HPRBs). The Hertz-damp model was adopted to simulate energy dissipation and the change in stiffness during pounding. In accordance with the Chinese seismic code of bridges, actual ground motion records were selected for each site condition by using the spectrum match method, and then, a comparative analysis was conducted considering both the wave-path and local site effects. The results show that GMSVs not only increases the seismic responses of the bridge structure but also increases the amplitude and non-synchronous vibration of adjacent structures, which will result in more pounding. Therefore, special attention should be paid on the effect of GMSVs on the seismic design of high-pier bridges. Otherwise, the responses of the bridge structure will be incorrectly estimated. Moreover, the wave-path effect may become more evident for beam-beam pounding by changing the phase angle of ground motions, especially, for a lower apparent velocity, while the local site effect may become more evident for beam-abutment pounding by increasing the amplitude of ground motions. It is suggested that both GMSVs and the leading cause of pounding at different locations should be considered for adopting an appropriate seismic design method and measures to mitigate or prevent pounding.

Stochastic Analysis of Effective Moment of Inertia of Cracked In-Service Reinforced Concrete Beams

YANG Cheng, CHEN Wenlong, ZHAO Renda, XU Tengfei

2018, 53(3): 492-499. doi: 10.3969/j.issn.0258-2724.2018.03.009

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For cracked reinforced concrete structures in working service life, calculation of the stiffness of the cracked reinforced concrete beam is important for the serviceability design of reinforced concrete structures. However, owing to the uncertainty and nonlinearity of concrete, it is difficult to precisely predict the effective moment of inertia of cracked concrete beams. In this study, the dimensionless equation for the effective moment of inertia recommended in specification GB50010-2010 for in-service reinforced concrete beams was derived, and a Monte Carlo method was employed to analyse its stochastic properties. The dimensionless effective moment of inertia was calculated using both a stochastic analysis with random variables and a deterministic analysis with mean values of the parameters. The results indicate that the mean values obtained with the stochastic analysis are not in agreement with those calculated with the deterministic analysis owing to the cracking nonlinearity of concrete. In addition, through regression of the stochastic analysis results, mean values of the effective moment of inertia are estimated at the 95% confidence interval. Finally, a sensitivity coefficient reflecting the correlation between each random variable and the effective moment of inertia was calculated using a partial correlation coefficient. The results demonstrate that the tensile strength of concrete is the most sensitive variable, while the compressive strength of concrete has nearly no effect on the effective moment of inertia.

Experiment Research on Seismic Behavior of Steel Reinforced Concrete Shear Walls of Concealed Bracings

WANG Yuzhuo, HUANG Ying, WANG Huimin, FU Chuanguo

2018, 53(3): 500-507. doi: 10.3969/j.issn.0258-2724.2018.03.010

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Three steel reinforced concrete shear walls with concealed bracings and one common concrete shear wall were tested under a low cyclic reversed load condition to investigate the seismic behaviour and the effect of having a different number of concealed bracings. The failure characteristics of steel reinforced concrete shear wall specimens were comparatively analysed. These failure characteristics included bearing capacity, stiffness, ductility, hysteretic behaviour, and energy dissipation capacity. The test indicated that the cracks of steel reinforced concrete shear wall specimens were narrower and distributed more widely than the common shear shear wall specimens. Also, the plastic hinge and hysteresis curve developed more fully, and energy dissipation capacity was improved significantly. Compared to a common shear wall, the yield load and ultimate load of the steel reinforced concrete shear wall were increased by 88.76% and 91.97%, respectively. In addition, the limit displacement angle was increased by 26.67%. Furthermore, the seismic capacity was improved significantly.

Investigation into Effects of Turbulence Integral Length on Wind Loads Acting on Tall Buildings Using Large Eddy Simulation

ZHU Zhiwen, DENG Yanhua

2018, 53(3): 508-516. doi: 10.3969/j.issn.0258-2724.2018.03.011

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To investigate the influence of turbulence integral length on the wind pressure value and distribution on the surface of tall buildings and determine the reasonable value of turbulence integral lengths, a large eddy simulation (LES) was conducted under different turbulence integral lengths to represent the wind flow field around the commonwealth advisory aeronautical research council(CAARC)standard tall building model in exposure category B. The obtained results were compared with those from the wind tunnel test. It is found that the LES is a feasible tool to represent the wind flow around a high building and the distribution of wind pressure on the building surface. It is also found that with the increase in the turbulence integral length, the energy of turbulent fluctuation increases, resulting from the deformation of flow average movement; the mean wind speed will decrease, and hence, the turbulence intensity will increase. It is also found that the fluctuation of wind pressure decreases by 15% on the side face, while the reattachment point of separated flow moves forward. Meanwhile, the local peak at the high-frequency range as well as the peak of aerodynamic base moment and torque spectrum decrease. While the Strouhal number of the layer is essentially the same at a height lower than 0.4 times the height of the building, it decreases by 20%-30% with the increase in height, and the drag coefficients of the mean layer decrease by 5%-10%. The results also show that the mean coefficients of the wind pressure in the windward side reduce by 2%-5%, with a decrease of 12%-17% in the crosswind side and leeward side. The investigation further finds that the turbulence integral length has minor effects on correlations of horizontal wind pressure in the windward side and crosswind side in the upwind direction, and the lift on the layer and drag on the layer at a height less than 0.8 times the height of the building. With the increase in the turbulence integral length, the correlation coefficient of the horizontal wind pressure increases respectively by 5%-10%and 15%-25% in the leeward and crosswind sides in the downwind direction, and the correlation coefficient of the drag of the layer increases by 25%-50% at a height above 0.8 times the height of the building. When the adjustment coefficient of the turbulence integral length in exposure category B is 0.4, the results of wind load obtained by LES are more consistent with the test results.

Consistency between Calculated and Tested Values of Critical Flutter Speed of Flat Box Girder

WU Bo, WANG Qi, LI Zhiguo, LIAO Haili

2018, 53(3): 517-524. doi: 10.3969/j.issn.0258-2724.2018.03.012

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To obtain the precise flutter performance of a flat box girder, concordances between calculated values and tested values of critical flutter speed were studied, using sectional model wind tunnel testing combined with the calculation method of critical flutter speed. The flutter derivatives under different wind attacks of the box girder were obtained using forced vibration tests. The critical flutter speeds were then calculated using the bimodal coupled flutter analysis method. Finally, the critical flutter velocities were obtained via the sectional model tests under the same conditions. The results indicate that the differences between calculated and tested critical speeds in all cases are minor, and the percent errors are less than 5% when the attack angle is 0°. The differences between calculated and tested critical speeds are substantial when the attack angles are 3° and 5°, and the percent error can reach 10.4%. Based on a comparison of flutter factors derived from the calculation and the test, excluding the effect of nonlinear aerodynamic force and structural damping, it is conjectured that the differences may have been induced by variation in flutter derivatives caused by different coupled motions.

Study of Three-Dimensional Wave Forces on Lowering of Steel-Suspending Cofferdam

HUANG Bo, DUAN Lunliang, ZHU Bing

2018, 53(3): 525-532. doi: 10.3969/j.issn.0258-2724.2018.03.013

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In order to understand the interaction between dumbbell shaped steel boxed cofferdam and wave during the construction of the bridge across the sea. The interaction between a steel-suspending cofferdam and wavesis studied, to investigate the influence of waves on the construction progress of the large dumbbell cofferdam. A numerical model for wave-cofferdam interactions is established, in which the Reynolds-averaged Navier-Stokes equations and k-ε model are used to generate waves, while the VOF(volume of fluid) method is used to trace the water surfaces. The influence of the steel tube and the lowering of the cofferdam on the wave field around the cofferdam are considered. The numerical simulation results show that the steel tube and lowering of the cofferdam have significant effects on the wave field around the cofferdam. Consideration of the lowering of the steel-suspending-cofferdam, the wave forces on the cofferdam will be 10% larger than that on the cofferdam with a certain submerged depth. With increments of the wave height and wave period, the wave forces acting on the lowering steel-suspending cofferdam tend to increase.

Numerical Study of Flow Characteristics Around Square Cylinder at High Reynolds Number

ZHOU Qiang, LIAO Haili, CAO Shuyang

2018, 53(3): 533-539. doi: 10.3969/j.issn.0258-2724.2018.03.014

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Three-dimensional large eddy simulations (LES) were performed at high Reynolds numbers (Re=22 000) and using the dynamic Smagorinsky sub-grid model to investigate uniform flow over a square cylinder. Meshing of the model was performed using Open Foam-an open-source computational tool. Mean integral quantities were compared against existing experimental and numerical results to validate the proposed numerical method. Subsequently, the flow structure around and aerodynamic forces acting on the cylinder were analysed to perform an in-depth investigation of mean-and turbulent-flow characteristics. Lastly, the influence of the grid system around the cylinder and span-wise length on the flow structure and spatial correlation were investigated via comparison between different cases. Results demonstrate that the recirculation length in the wake approximately measured 1.37D (width of square), while the Strouhal number and RMS value of the lift coefficient are 0.121 and 1.40, respectively. In addition, domain length along the span-wise should be equal to 8D in order to obtain clear turbulent-flow characteristics.

Study on Isolated Reinforcement Scheme of Ancient Masonry Pagoda in Sichuan Province

PAN Yi, WANG Zichao, SHANG Feng, GE Qingzi, YUAN Shuang

2018, 53(3): 540-547. doi: 10.3969/j.issn.0258-2724.2018.03.015

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In order to more effectively protect masonry pagodas and retain their original historical style and features, Pengzhou Zhenguo White Pagoda was examined as a representative case. The isolation performance of the pagoda was analysed using different isolation schemes as parameters. The vertex maximum acceleration, interlayer displacement, and shear force values under rarely severe earthquake before and after isolation were compared, and the wind resistant and anti-overturn status after isolation were calculated. The results showed that the seismic response could be reduced under a rare earthquake by selecting larger isolation bearings and an outer edge arrangement. The maximum acceleration of the vertex was decreased by approximately 80%, while the horizontal shear was decreased by approximately 70%, which effectively improved the seismic safety of the masonry pagoda.

Simulation and Macro-Mesoscopic Parameter Analysis for Direct Shear of Filled Rough Joints

XU Wanzhong, LIN Hang, CAO Rihong

2018, 53(3): 548-557. doi: 10.3969/j.issn.0258-2724.2018.03.016

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A joint model based on particle flow was built successfully and the mechanical properties of the fill joint were investigated in this study. The morphology of damage and the crack evolution mechanism of roughness of the jointed model were also analysed from the viewpoint of meso-mechanics. At the same time, the influence of the value of the JRC(joint roughness coefficient), fill strength, interface, and fill thickness on the mechanical behaviour have been analysed. The detailed results are as follows:(1) The normal stress has a significant influence on the peak shear stress, contact condition, and contact force of the joint. With higher stress, the bond break at the joint surface becomes apparent; (2) The joint peak shear stress increases with an increase in the JRC value, and the shear strength parameters for cohesion and friction angle exhibit linear and nonlinear increases with the increase in the JRC value, respectively; (3) The joint peak shear stress increases with the strength of filling material. However, the strength of filling material has a different influence on the cohesion and friction angle of the fill joint. Cohesion increases with an increase in material strength. The friction angle decreases as the fill strength ratio changes from 0.1 to 0.3, and increases when the fill strength ratio exceeds 0.3; (4) When the normal constant load is small, the interface has a significant influence on the peak shear stress, but when the normal constant load is large, the influence is weaker. Joint shear-strength parameters for cohesion increase with the increase in the strength of interface, but the friction angle shows the opposite trend with cohesion; (5) With increasing fill thickness, the mechanical parameters of the joint model exhibit an obvious downward trend. However, with a further increase in thickness, the decrement in the mechanical parameters is less pronounced.

Improvement in Definition of Joint Parameters in Discontinuous Deformation Analysis

WANG Jinmei, ZHANG Yingbin, ZHAO John X., YU Pengcheng, WANG Pan

2018, 53(3): 558-564, 573. doi: 10.3969/j.issn.0258-2724.2018.03.017

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To improve the accuracy of value assignment for the joint parameters in the discontinuous deformation analysis (DDA) program, an improved method for definition of the joint parameters was proposed based on the definition of the joint parameters in the DDA original program. First, according to the physical and mechanical properties of joints, the problem of inconsistency regarding the definition of the joint parameters in the original DDA was analysed. Second, because the joint attribute was determined by the two structural planes of a joint, the joint parameters in the program were redefined. Last, the code for parameter assignment was modified and complemented, and the process flowchart was provided. An example of the relative sliding of two blocks was studied to examine the improved DDA program. The results show that, when the mechanical parameters of blocks 1 and 2 are exchanged, the joints between the two blocks are still joints with the same nature. Under both conditions, the velocity and displacement of Block 1 remain the same. The results also indicate that the improved DDA program can achieve unity of the parameter assignment of the joints.

Preliminary Study of Assessment System for Subsurface Karst Development Degree

ZHANG Kai, HUO Xiaolong, CHEN Shougen, TU Peng, TAN Xinrong

2018, 53(3): 565-573. doi: 10.3969/j.issn.0258-2724.2018.03.018

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An attempt was made to establish an assessment system for subsurface karst development by combining quantitative and qualitative methods. The assessment results can assist the preliminary determination of the extent of underground karst development and guide the planning and construction of underground engineering projects. Firstly, the major factors influencing the karst development were selected as the assessment indices in the system, and the varying degrees of subsurface karst development are defined. Then, the weights of these assessment indices were determined using a synthetic weighting method, in which the fuzzy hierarchy analytic process determines the qualitative weights, while the quantitative weights were determined by a sensitivity analysis of the Bayesian belief network. The Fuzzy Analytic Hierarchy Process was used to determine the ratings of the karst development states in the assessment indices. Moreover, based on the statistical data, the quantitative assessment results belonging to each degree of karst development were determined by comparing the calculated assessment results with the real karst development status. The proposed assessment system was applied to a railway tunnelling project in China to evaluate the degree of surface karst development before tunnel construction. A comparative analysis of the assessment results with the recorded results shows that the assessment of the tunnel zone, accounting for 97.1% of the total tunnel length, is consistent with the recorded results. Assessment errors only occur in 2.9% of the tunnel zone, where the degree of karst development was assigned as "developed", while the records indicated it was "extremely developed". However, the quantitative assessment result of the karst development degree is 0.69, which is close to the value range of "extremely developed", 0.70-1.00. As this minor error is acceptable in the preliminary assessment of the degree of karst development, the proposed assessment system is verifiably reliable.

Multiple Model Analysis for Studying Groundwater Uncertainties

SONG Kai, LIU Dan, LIU Jian

2018, 53(3): 574-581. doi: 10.3969/j.issn.0258-2724.2018.03.019

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Multiple Model Analysis was applied to study the groundwater modelling uncertainties caused by the deviation of model structure and heterogeneity in aquifer media. According to different natural conditions, two hydrogeological conceptual models were established. Using a large number of model parameter data, obtained through hydrogeological tests, as a priori information and based on the two conceptual models, a series of seepage field models was constructed using the Adaptive Metropolis-Markov Chain Monte Carlo method that acceptance condition was adjusted. Uncertainties of modelling output data are analysed based on corrected Akaike's Information Criteron. Research indicates that the ergodicity and convergence of sample parameters will not be affected by changes in acceptance conditions. The model output data include the following effects:"same results with different parameters" and "same results with different models". Although these effects exist, the model structure is closer to the objective of improving the probability of obtaining a high precision model. The proportion of the primary conceptual model, with a variance between 1 and 2, is 65%. When the model with Delta values greater than 10 is excluded, the top 10 models are retained and the cumulative a posterior probability is 0.996. The proportion of the second conceptual model, with a variance between 1 and 2, is 46%. When the model with Delta values greater than 10 is excluded, the top 21 models are retained. The cumulative posterior probability of the top 10 models is only 0.884.

Algorithm Development and Application of Double-Yield-Surface Elastoplastic Constitutive Model for Earth-Rock Materials

CEN Weijun, CHEN Sining, Deng Tongchun, XIONG Kun

2018, 53(3): 582-588. doi: 10.3969/j.issn.0258-2724.2018.03.020

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To enrich the constitutive models of geotechnical materials in universal commercial finite-element analysis software suites, e.g. ADINA, ABAQUS, and ANSYS, and to improve the precise simulation ability for certain geotechnical structures, Shen's double-yield-surface elastoplastic model was chosen as an example to introduce in detail the secondary development process of a constitutive model in commercial finite-element software. The stress integration algorithms were modified, and the superiority of the algorithms was investigated by comparing the numerical simulation with triaxial test data for coarse-grained soil. Further, an ideal concrete-face rockfill dam was used to validate the accuracy of the secondary development process and the algorithms. Finally, the numerical simulation of a practical concrete-face rockfill dam was conducted. The results indicate that the stress integration algorithms and the secondary development process presented in this study are universal and can be employed for the secondary development of double or multi-yield-surface elastoplastic models in universal finite-element analysis software.

Predictive Controller with UKBF for Marine Dynamic Positioning System

SU Yixin, ZHAO Jun, ZHANG Huajun

2018, 53(3): 589-595. doi: 10.3969/j.issn.0258-2724.2018.03.021

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For surface vessel dynamic positioning (DP) system controls, a design method for predictive controllers is proposed based on the unscented Kalman-Bucy filtering (UKBF) algorithm and on a non-switching analytical model predictive control (NSAMPC) method. To avoid linearization and discretization errors in the model, the UKBF algorithm was applied to determine motion-state estimates of the ship. On the basis of the relative degree concept and non-linear ship motion models, an NSAMPC controller was designed in order to maintain a floating vessel at a specific position. The proposed method was verified by performing simulations on a marine supply vessel. The simulation results exhibit a smoother output of the designed controller, which is helpful for reducing the wear on the propeller. Moreover, the proposed controller results in a settling time of less than 40 s for the north position of the vessel with an overshoot of less than 5%. Likewise, the controller results in an east-position settling time of less than 60 s with an overshoot of less than 5%. In addition, the maximum offset of the vessel heading angle is less than 1.5°. The proposed controller allows the ship to reach the specific position quickly.

Effect of Thread Wear on Anti-Loosening Ability of Threaded Fastener under Vibration

ZHANG Mingyuan, LU Liantao, ZHANG Yuanbin, ZHANG Jiwang, ZENG Dongfang

2018, 53(3): 596-601. doi: 10.3969/j.issn.0258-2724.2018.03.022

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Abstract:
In order to improve the anti-loosening ability of threaded fasteners under vibration, the anti-loosening abilities of the electro-zinc-plated fastener (EZP) and the electro-zinc-plated fastener treated by fine particle peening (FPP-EZP) were evaluated using a fastener transverse vibration apparatus. The surface damage and worn dimensions of the thread before and after testing were observed and measured using scanning electron microscopy. Then, a fastener stiffness model considering thread wear depth was used for numerical simulation of the effect of the wear depth on the threaded fastener preload. The test results show that the preload endurance limits of the EZP and FPP-EZP are respectively 2.8 kN and 2.0 kN, this suggests that the anti-loosening ability of the EZP is lower than that of the FPP-EZP. The observation results show severe damage on the thread surface for EZP, but no distinct damage on the FPP-EZP threads. The numerical simulation shows that the thread wear depth increases with the increase of the relative sliding distance between threads. Furthermore, the preload initially decreases nearly linearly with the increase in thread depth, and then rapidly. The thread wear can reduce the anti-loosening ability of threaded fasteners.

Design and Analysis of New Type of Piston Pump

LIN Chao, WEI Yanqun, ZHAO Xianglu, WU Xiaoyong

2018, 53(3): 602-609. doi: 10.3969/j.issn.0258-2724.2018.03.023

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Abstract:
To improve the pulsating performance of a swashplate piston pump, a new type of double-acting piston pump is designed based on the meshing theory and the related knowledge of geometry. The pump is driven by the double curve-face gear and its pistons drain oil uninterruptedly. By using the transmission principle of the curve-face gear pair, the engagement coordinates of the double curve-face gear and piston motion analysis coordinates were established. The piston structure was designed according to the working characteristics of the piston pump, and the piston distribution of a new type piston pump is discussed. The equations of piston displacement, velocity, and instantaneous flow were deduced based on the working principle of the proposed double-acting piston pump, and the factors affecting the flow pulsation rate, such as the number of plungers, eccentricity, and the order of curve-face gear, were analysed. The analysis results show that compared with the existing swashplate piston pump, the variation in the flow pulsation rate of the proposed double-acting piston pump is more stable, and the flow pulsation rate decreases with increase in the number of plungers, decrease in the eccentricity, and increase in the order of the curve-face gear. The test-bed was used to test the plunger velocity, and the maximum error value is 4.79 mm/s.were in good agreement with the theoretical values; the error was less than 5%, which is within the allowable range of error.

Research and Prospect on High-Speed Catenary Component Failure

TAN Deqiang, MO Jiliang, PENG Jinfang, LUO Jian, CHEN Weirong, ZHU Minhao

2018, 53(3): 610-619. doi: 10.3969/j.issn.0258-2724.2018.03.024

[Abstract](601)

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Abstract:
The failure of catenary components seriously affects the operational safety of a catenary system, and the reliability of the catenary system provides an important foundation for the safe operation of trains and railway lines. In order to promote the development of high-speed catenary equipment technology, the typical failures and causes of catenary components were systematically summarised and analysed based on the results of field research, including the wear of aluminium-alloy positioning hooks and supports, fatigue of droppers, bolt loosening, slipping of terminal anchoring clamps, and corrosion of parts. It was noted that fretting damage (fretting wear and fretting fatigue) and poor working conditions were the main factors behind the failure of catenary components. Then, the research status of fretting wear, fretting fatigue, bolt loosening, and stress corrosion in China and abroad were introduced. Moreover, research prospects were proposed for the damage mechanism of impact-sliding wear, fretting fatigue of multi-wire strands, bolt loosening, fatigue damage under the condition of current-carrying and corrosion fatigue, and the importance of a high current for studying damage was indicated.

Decoupling Operation Mode of Controllable Reactor of Transformer Type

TIAN Mingxing, LI Jin, Gao Yuan, LIU Yibin, MIN Yongzhi

2018, 53(3): 620-627. doi: 10.3969/j.issn.0258-2724.2018.03.025

[Abstract](448)

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Abstract:
As there is an electromagnetic coupling between the windings of a controllable reactor of transformer type (CRT), the current passing through each control winding cannot be maintained at its rated value, causing a considerable waste of winding material. To solve this problem, a decoupling operation mode and its implementation scheme are presented, based on the idea of the multi-winding working mode. First, in accordance with the characteristics of the decoupling operation mode, the required current-limiting inductances are calculated, while the rated values of the winding current are given. Second, in accordance with the rated value of the current for each control winding, the regulating range is graded, and then the current of every control winding is discretized discretized in each grade. Third, based on the mathematical model for calculating the values of the winding current of a CRT, all discrete points are calculated step-by-step, and then the trigger angle regulating rule, which makes the control winding current constant after meeting the rated value, is obtained. Finally, a simulation experiment is conducted, by employing a CRT, for which the control windings rated values for the current are 9.16, 11.59, 24.52, 51.85 A, and 109.64 A respectively. The results show that the values of the control winding current are maintained at their rated values under the decoupling operation mode.

Pareto Hybrid Ant Colony and Genetic Algorithm for Multi-Objective U-Shaped Disassembly Line Balancing Problem

ZHANG Zeqiang, WANG Kaipu, ZHU Lixia, CHENG Wenming

2018, 53(3): 628-637, 660. doi: 10.3969/j.issn.0258-2724.2018.03.026

[Abstract](483)

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Abstract:
Owing to the incapability of traditional methods in solving multi-objective U-shaped disassembly line balancing problem (UDLBP), a multi-objective ant colony genetic algorithm based on Pareto set is proposed to solve the UDLBP. In constructing the initial solution phase, the maximum operation time and the minimum disassembly cost difference were collaboratively considered as the heuristic information of the ants. The feasible disassembly sequence was searched using the ant colony algorithm, and the Pareto solution set was obtained based on the dominance relationship among the multiple objectives. Further, the Pareto non-inferior solutions of the ant colony algorithm were used as the chromosomes of the genetic operator. Moreover, the results of the genetic operator were fed back to the accumulation of pheromone on the optimal disassembly sequence. The crowding distance was regarded as the global pheromone update strategy to balance the effect of multi-objective function regarding the pheromone and thereby make the algorithm obtain better solutions readily. The proposed algorithm was applied to 52 disassembly task examples and a printer disassembly line instance. Compared with the Pareto ant colony algorithm, the performances of the three evaluation indicators of the 8 non-inferior solutions obtained using the proposed algorithm are improved by 50.43%, 3.25%, and 14.10%, respectively. In the example application, the proposed algorithm obtained eight balancing schemes, which verifies the effectiveness, superiority, and practicability of the proposed algorithm.

RBF Neural Network Robot Manipulator Control Based on Fuzzy Compensation

MAO Run, GAO Hongli, SONG Xingguo

2018, 53(3): 638-645. doi: 10.3969/j.issn.0258-2724.2018.03.027

[Abstract](359)

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Abstract:
For achieving high precision trajectory tracking control of robot manipulators, a control strategy based on fuzzy logic compensation for radial basis function (RBF) neural networks has been proposed. First, the output of a proportional-integral (PD) controller was used in conjunction with an RBF neural network for obtaining a dynamic model of the robot manipulator system. A fuzzy compensator was then introduced for addressing the modelling errors and external disturbances. Furthermore, the fuzzy compensator control scheme and the non-fuzzy compensator control scheme were applied to two-degrees-of-freedom robot manipulators through simulation with MATLAB and Simulink, and the root mean square deviation of tracking errors was thereby measured. The obtained results show that the control accuracies of the first and second joints of the robot manipulators can be improved by 60.8% and 71.4%, respectively. Furthermore, the proposed control scheme can be applied to such robot manipulators which cannot be precisely modelled by compensating the non-modelled part and external disturbances of the system.

Adaptive Imaging Control System Based on Traffic Video Analysis

ZHANG Hongbin, HUANG Shan, YIN Yue

2018, 53(3): 646-653. doi: 10.3969/j.issn.0258-2724.2018.03.028

[Abstract](387)

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To ensure accurate video detection and data collection under high dynamic illumination and complicated road conditions, an adaptive traffic imaging control system was developed. A high-definition traffic imaging system was designed to meet the needs of full-time wide-field comprehensive detection. The control characteristics of the imaging parameters were acquired through system identification. Based on license-plate properties and traffic scenes, a video-analysis algorithm computing mid-values of license-plate images and road-marking blocks as feedback control variables, was proposed. In an adaptive control framework combining low-level image-quality feedback and high-level visual-detection results, autonomous illumination-mode adaption and control-state switching were realized. The experimental and application results show that the system control process is fast and stable. It can adapt to different illumination conditions, balance the requirements of high-definition license-plate recognition and wide-field traffic surveillance, maintain good all-day imaging effects, and achieve 97.0% traffic-flow accuracy and a 96.3% license-plate recognition rate.

Risk Transfer Mechanism and Control in Logistics of Fresh Agriculture Product Supply Chain

FU Zhuo, YAN Yusong, GUO Qian, QIU Zhongquan

2018, 53(3): 654-660. doi: 10.3969/j.issn.0258-2724.2018.03.029

[Abstract](526)

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Abstract:
In order to better reflect the transmission of financial risk caused by the time deviation of a logistics operation, the transmission problem of overdue risk caused by logistics delays in the supply chain of fresh agricultural products was analysed, based on the condition of time constraints of a logistics service. First, by applying the principles of disease transmission of lemology, the three infectious elements, which are infection source, transmission carrier, and infected person, were introduced into the identification of logistics risk transmission, and five risk factors were established. These included logistics operation standards, management ability, environmental protection, logistics extension, and spatial risk transmission. Then, the numerical analysis of an iterative method was used to calculate the value of the supply chain overdue risk based on the risk transfer model of logistics of a fresh agricultural products supply chain. In addition, the factors that influence the overdue risk value of a supply chain, which is affected by controlling risks, were studied including internal nodes, spatial transfer, and logistics delay. These were analysed using an example. The analysis showed that calculating the risk node is beneficial to finding the key node for controlling risk transmission, and after optimizing the risk elements of key nodes it can be used to reduce the risk value effectively for the circumstance when the supply chain follows a single logistics direction. In the example analysis, nodes 2 and 4 were recognized as the key nodes for generating the supply chain overdue risk and their risk values were calculated as 0.45 and 0.39, respectively. After the factors were optimized the overdue risk value of the supply chain was reduced from 0.39 to 0.29.

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2018 Vol. 31, No. 3