Table of Content

25 November 2022, Volume 50 Issue 11

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2022, 50(11):  0-0. 

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Traffic & Transportation Engineering

Road Markings Condition Assessment Method for Intelligent Vehicles



FU Xinsha, PENG Jinhui, ZENG Yanjie, et al

2022, 50(11):  1-13.  doi:10.12141/j.issn.1000-565X.220126

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With the continuous advancement and popularization of autonomous driving technology, more and more vehicles with autonomous driving technology will appear on the road, and the service objects of road markings will gradually transition from drivers to autonomous vehicles.On the one hand, the method of road markings condition assessment requires a lot of manpower to inspect, measure and evaluate; on the other hand, the evaluation index is based on biological vision research, which does not conform to the characteristics of automatic driving vehicles based on machine vision. To solve the above problems, this paper proposed a method of road markings condition assessment for autonomous vehicles. First, PSNR(peak signal-to-noise ratio) was initially determined as the evaluation index by means of literature review, analogical reasoning and logical reasoning. Secondly, to quickly obtain PSNR, this paper proposes a calculation method of the PSNR based on image inpainting, which utilizes the DeblurGAN model restores the damaged road markings at the image level, and then uses the damaged and restored road markings images to calculate the PSNR. In addition, this paper proposed a data augmentation method that can realis-tically synthesize damaged road markings images to improve the performance of image inpainting models. Then, the AlexNet network was used as the benchmark model to design experiments to study the relationship between the PSNR and the recognition accuracy of road markings. The experimental results show that, compared with the calculation method of the PSNR based on the artificially restored image, the average PSNR obtained by the method proposed in this paper only differs by about 2.24%, but the acquisition speed is increased by about 418 times; when the average PSNR differs by about 43.66%, the average recognition accuracy differs by about 36.27%. Therefore, the PSNR can measure the use of road markings. Compared with the evaluation method of the current standard, the evaluation method proposed in this paper improves the work efficiency by about 6.5 times and consumes less manpower. And it is more in line with the characteristics of self-driving cars, but the evaluation methods are more detailed in the specification.

Study on the Choice of Morning Peak Departure Time of Heterogeneous Car Commuters Considering Travel Anxiety



HU Yucong, LUO Mingming, PAN Lei, et al

2022, 50(11):  14-24.  doi:10.12141/j.issn.1000-565X.220004

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Private car commuters were divided into two groups: group I who feel anxious about road congestion and group II who are more concerned about whether they can arrive punctually. The trip sensitivity coefficient (congestion anxiety coefficient, punctual anxiety coefficient) and the bottleneck tolerance coefficient were introduced to characterize the travel anxiety level of the two types of commuters. A new trip cost function was developed based on the standard bottleneck model and was applied to analyze indicators such as departure-rate, peak-start-end time and commuter-composition in single and shared routes. The results show that when there is only a certain type of commuters on the road, the increase of the congestion anxiety coefficient, bottleneck tolerance coefficient and punctual anxiety coefficient will reduce the total perceived travel cost of the system for commuters on a single line. The number of group II increases, the total perceived travel cost of system decreases, and the peak period shifts forward as the punctual anxiety coefficient of group II in mixed situation 1 rises; the total perceived travel cost of system falls as the bottleneck tolerance coefficient increases, while the peak period moves back. In the mixed situation 2, the congestion anxiety coefficient and the bottleneck tolerance coefficient of group I have dual effects on the number of this group, and under the combinations of different bottleneck tolerance coefficient and congestion anxiety coefficient, the attractiveness of this group exhibits three different trends: monotonically decreasing, first decreasing and then increasing, and monotonically increasing.

Analysis of Propagation Mechanism of Recurrent Congestion Based on Dynamic Bayesian Network



CHENG Xiaoyun, QU Xiaping, ZHANG Xueyu, et al

2022, 50(11):  25-34.  doi:10.12141/j.issn.1000-565X.210744

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In order to accurately identify the propagation path of recurrent congestion and analyze its propagation mechanism to alleviate the traffic congestion at the source and block the propagation path, this study proposed a method of analyzing the congestion propagation mechanism based on taxi GPS data. Firstly, the number of vehicle trajectories and travel speed were used to identify the traffic congestion area based on the space-time cube model of urban road network. According to the relative spatio-temporal stability of recurrent congestion, a time-section recognition method of recurrent traffic congestion grid was proposed. Secondly, the spatio-temporal congestion propagation trees was constructed. Aiming at the dynamics of traffic congestion propagation, a method of mining frequency-weighted recurrent propagation relation set was proposed to construct recurrent congestion propagation subtrees. Thirdly, the Dynamic Bayesian Network was introduced to obtain the congestion propagation probability through Bayesian estimation. Finally, taking the eastern section of the South Second Ring Road in Xi'an as an example, the proposed method was used to conduct an empirical analysis to explore the congestion propagation path and its probability. The research results show that based on the space-time cube model, the recurrent congestion grids in each time frame identified by the number of vehicle trajectories and travel speed lay the foundation for the accurate analysis of the congestion propagation mechanism. The congestion propagation trees constructed by using the STC algorithm, and the proposed frequent itemsets mining method considering temporal reproducibility characteristics of congestion propagation can be used to reconstruct the recurrent congestion propagation subtrees and clarify the propagation path of recurrent congestion. The possibility of congestion propagation between grids was analyzed based on the Dynamic Bayesian Network. It provides a theoretical basis for dynamically finding the key segment in the congestion propagation network, scientifically and reasonably formulating the congestion alleviation scheme and the task timeline.

Anti-Cracking Property of UHPC-NC Structure in the Negative Moment Zone of PC Beam Bridge



LI Xiao, HU Zhijian, HE Yan

2022, 50(11):  35-43.  doi:10.12141/j.issn.1000-565X.210650

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To improve the anti-cracking performance of the negative bending moment zone of the continuous prefabricated beam bridge, this paper proposed a UHPC-NC (normal concrete) structure with a high reinforcement ratio (larger than 1.5%) in the negative bending moment zone of an assembly continuous beam bridge. Taking A PC continuous beam bridge on the Nanchang to Jiujiang expressway as the engineering prototype, the study carried out the scale model tests with the scale ratio of 1∶4 in the transverse direction and 1∶5 in the longitudinal direction. Then, based on the "plane section" assumption, it developed the calculation methods formula of the cracking moment for the connection structure under different bearing modes. The influences of the thickness of the UHPC layer and reinforcement ratio on the cracking moment were analyzed by means of the finite element method. The results show that the cracking moment with the UHPC layer in the negative moment zone of the continuous girder bridge is improved significantly. The feasibility of the connection structure and the validity of the finite element model were verified and the calculation method of cracking moment in this paper is reliable and can provide reference for design and engineering application. the relative error of the reinforcement ratio between the finite element method and the method in this paper is within 10%. Under the action of pure moment and bending shear combination, the cracking moment of UHPC-NC structure increases with the increase of UHPC layer thickness and reinforcement ratio.

Optimization of Train Planning for General Tree-Type Line



WEI Runbin, JIA Shunping, TONG Ruiyong, et al

2022, 50(11):  44-51.  doi:10.12141/j.issn.1000-565X.220140

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In the background of rail transit network operation, the simple line and routing forms can no longer meet the diverse passenger travel demand. Therefore, in order to cope with the mismatch between traffic supply and demand brought about by passenger trips in complex directions, the paper proposed a rail transit line form of general Tree-type line based on the existing research on Y-type lines, and it was divided into diameter type and radius type with reference to the actual operating line cases. Firstly, the paper designed a line topology form of Tree-type line and established a multi-routing planning optimization model for Tree-type line by considering the distribution of passengers among different trains and taking the departure frequency as the decision variable and the passenger travel time and minimum operating cost as the target function. Then it designed and solved the non-dominant ranking genetic algorithm (NSGA-Ⅱ) with the elite strategy. The model and algorithm were validated using the RER A line in Paris as an example. Finally, the optimization scheme was compared with the split-line scheme. The results show that: the algorithm can find the Pareto frontier solutions of the train planning, and the travel time of passengers and the operation cost of enterprises show a significant negative correlation; the obtained optimization scheme has a significant reduction in the travel time of passengers and the operation cost of enterprises compared with the split-line scheme. It reduces the waiting time of passengers by 1.76% to 12.90%, the transfer time of passengers by 33.63% to 34.98%, the total running kilometres of trains by 7.69% to 21.67%, and the the number of trains on the line by 9 to 19.

Biological Engineering

Safety Evaluation and Probiotic Characteristics of Enterococcus faecalis EF-ZA1107-06



XU Xilin, ZHONG Shuying, ZHOU Xiaoli, et al

2022, 50(11):  52-61.  doi:10.12141/j.issn.1000-565X.210731

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Enterococcus was isolated from 1-month-old baby feces in Guangzhou and the strain was identified as Enterococcus faecalis by molecular biology and was named Enterococcus faecalis EF-ZA1107-06. The strain was evaluated for its safety and some probiotic potential properties. The results show that the strains does not produce nitroreductase and has no hemolytic activity. It is highly sensitive to many kinds of antibiotics, does not contain plasmids, and has no acute toxicity to the mice. EF-ZA1107-06 was proved as an edible safe strain. High tolerance was observed by EF-ZA1107-06 strain for simulated gastrointestinal condition. After continuous exposure to simulated saliva for 10 min, simulated gastric juice for 2 h, and simulated intestinal juice for 3 h, the survivability was still above 65%, which was comparable to that of Lactobacillus rhamnosus GG (LGG). EF-ZA1107-06 can inhibit the growth of Escherichia coli, Salmonella, Pseudomonas aeruginosa, Candida albicans, Listeria monocytogenes, Staphylococcus aureus. The inhibitory effect of its supernatant on Escherichia coli is significantly stronger than that of LGG. The supernatant, lysate and suspension of the EF-ZA1107-06 strain all have certain DPPH free radical scavenging capacity and hydroxyl radical scavenging ability. DPPH free radical scavenging rate of 2×10⁸ CFU/mL EF-ZA1107-06 suspension is（93.16±0.17）%. The hydroxyl radical scavenging rate of the suspension is（90.48±1.12）%. The cholesterol removal rate of 2×10⁸ CFU/mL EF-ZA1107-06 fermentation broth is （44.29±0.30）%. The EF-ZA1107-06 strain has high cholesterol scavenging ability.

Effects of Vitamin D Supplement on Gut Microbiota in Nonalcoholic Fatty Liver Disease Patients



HAN Yuanping, XU Siya, JIAN Xile

2022, 50(11):  62-73.  doi:10.12141/j.issn.1000-565X.210715

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To explore the effect of VD supplement on the gut microbiota of NAFLD patients, this paper carried out a controlled clinical research on 29 NAFLD patients who were randomly divided into control group (n=15) who received the standard care and internal medical treatment, and VD treatment group (n=14) who received the standard care and internal medical treatment plus high dose of VD₂ treatment. According to Chinese Pharmacopoeia, NAFLD patients were given 600 000 IU VD₂ by intramuscular injection at once. At day 30, serum biochemistry indicators were determined, stool samples were collected, and the fecal microbiota was measured by 16S rRNA sequencing analysis. The diversity and abundance of microbiota before and after the VD₂ treatment were compared and the correlation between microbiota and biochemistry indicators was detected. The results show that after VD supplement, the serum alanine aminotransferase (ALT) of NAFLD patients is significantly decreased（P<0.001）, and there is no significant change in the gut microbiota diversity. However, there is a significant decrease in family Lachnospiraceae (P<0.01), a significant increase in family Erysipelotrichaceae (P <0.01) and genus unidentified_Erysipelotrichaceae (P<0.05) after VD supplement; the relative abundance of family Lachnospiraceae was significantly positively correlated with serum triglycerides (TG) levels (P<0.05); the relative abundance of family Erysipelotrichaceae (P<0.01) and genus unidentified_Erysipelotrichaceae (P<0.05) were significantly positively correlated with 25(OH)D, negatively correlated with serum ALT, serum aspartate aminotransferase (AST) (ALT: P<0.000 1, AST: P<0.05). In conclusion, VD supplement can reduce the serum ALT significantly, and alleviate the liver injury of NAFLD patients. VD_{can significantly reduce the abundance of Lachnospiraceae, significantly increase the abundance of Erysipelotrichaceae, unidentified_Erysipelotrichaceae, then decrease serum TG, serum ALT and serum AST.}

Proteomic Analysis of CHO-DG44 Cell Line Expressing Foreign Protein



XIE Qiuling, TAN Chumin, WANG Yayu, et al

2022, 50(11):  74-81.  doi:10.12141/j.issn.1000-565X.220031

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To provide the background for the genetic engineering modification of cell line, this paper compared two CHO-DG44 cells from different sources in terms of their differences in growth, metabolism and expression of exogenous protein TNFR-FC. ITRAQ combined with 2D LC-MS/MS were used to compare the protein expression profiles between CHO-DG44(A)/TNFR-FC cell, line and CHO-DG44 (B)/TNFR-Fc cell line, and protein-variety, GO enrichment and KEGG enrichment analysis were performed on the differential expression proteins. The results show that there are differences in cell growth, metabolism and exogenous protein expression between the two CHO cells. By comparing the protein expression profiles, it is found that there are 104 up-regulated proteins and 88 down-regulated proteins among 192 differentially expressed proteins. And enzymes accounted for the largest proportion (38.02%) among these differential proteins. The differentially expressed proteins are mainly enriched in biological processes like protein folding, glutathione metabolic process, carbohydrate metabolic process, intracellular protein transport, protein stabilization. These differential proteins are mainly related to pathways such as biosynthesis of amino acids, carbon metabolism, glycolysis/gluconeogenesis, citrate cycle, pyruvate metabolism and other signaling pathways. The differences in growth and metabolism, and expression of exogenous proteins between these two cell lines may be explained by the protomic differences in amino acid biosynthesis, carbon metabolism, glycolysis/gluconeogenesis, etc.

Architecture & Civil Engineering

Study on Mechanical Behavior of New Type Middle Joint of CFST Composite Column-Concrete Beam



LING Yuhong, LIAO Haopeng, XU Jinghang, et al

2022, 50(11):  82-94.  doi:10.12141/j.issn.1000-565X.210807

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In view of defects in the connection of concrete-filled steel tubular (CFST) composite column to concrete beam joint specified in the current code, this paper proposed a new type of fastener anchorage connection of beam to column joint with ring reinforcement in the column. The longitudinal reinforcement of the beam end of the concrete frame connected ring bar in column in forms of type, L-type and type and the ring bar set outside the steel pipe in the column was used to balance the tensile force from the beam end. Five specimens of concrete-filled steel tubular composite column concrete beam joints were designed for the monotonic static loading tests. The distribution and development of cracks, deformation, failure mode, bearing capacity, ductility of the middle joints and rebar strain development law were studied, and simulation analysis was performed using the ABAQUS software. The results show that ultimate failure modes of specimens with different joint anchorage are similar: the bending failure occurs at the end of beam, and all specimens possess good ductility and deformation ability. The yield of ring bars in columns lags behind the yield of longitudinal bars under tension, and no longitudinal bar slips off central bars during the test. The simulation results are consistent with the test results.

Experimental Study on Fatigue Behavior of Adhesive & Bolted Hybrid FRP Joints



WANG Jinxiao, LI Sida, CHENG Bin, et al

2022, 50(11):  95-106.  doi:10.12141/j.issn.1000-565X.220105

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FRP adhesive & bolted hybrid joint has the combined advantages of adhesive joints and bolted joints, which behave enhanced static performance, but its fatigue failure mechanism still needs to be studied. In order to study the fatigue performance of hybrid FRP joints under various working conditions, this study designed and manufactured single-lap hybrid FRP joints specimens. Firstly, the static load tests under axial tension loads and four side shear loads were carried out, and the corresponding failure modes and ultimate bearing capacity were obtained. Then, high cycle fatigue tests under two working conditions were carried out, and the damage process of the adhesive layer was measured by acoustic emission (AE) technology. The fatigue failure mode, characteristic fatigue life and stiffness degradation of the specimen were obtained, and the fatigue life prediction method was proposed. The results indicate that the anti- -fatigue performance of hybrid FRP joints is mainly controlled by bolted-connection, and its fatigue failure process can be divided into four stages: adhesive layer cumulative damage, adhesive layer failure, FRP cumulative damage, and FRP failure. Among them, the AE characteristic parameters of adhesive layer failure stage and FRP failure stage change significantly, and this can be used as the basis for identifying the failure occurrence. When the number of bolts is small, two working condition show the similar failure mode of the nut squeezing into the FRP plate. When the number of bolts is large, for tensile specimens, the tensile-shear failure mainly occurs at the hole of the FRP plate; for shear specimens, the failure mode is overall shear failure of FRP plate. The increase of the number of bolts can significantly improve the characteristic fatigue life of tensile specimens, and effectively inhibit the stiffness degradation during fatigue loads, but the improvement of fatigue performance of shear specimens is not obvious with the increasing number of bolts. The S-N curve of two working conditions obtained based on the test data can provide a reference for the fatigue life calculation of hybrid FRP joints, and help the application of such joints in bridges and other structures that mainly bear repeated loads.

Seismic Collapse Resistance Capacity of Buckling-Restrained Braced Steel Frame with Ductility-Enhanced Joints



HE Jinzhou, LÜ Dagang, JIA Mingming

2022, 50(11):  107-114.  doi:10.12141/j.issn.1000-565X.210632

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Under the actions of earthquakes, the damage distribution of Buckling-Restrained Braced Steel Frames (BRBFs) is usually not uniform. Once the beam-column joints or other components of BRBFs are destroyed, the high ductility of the buckling-restrained braces cannot be fully achieved. The local failure and the weak stories of BRBFs would cause the structures to collapse. Therefore, this paper proposed the scheme of two improved ductile beam-column joints and applied it in the BRBFs to achieve the high ductility by coordinating the global ductility of the structure and the local ductility of the ductile joints and members. Firstly, the finite element models of the BRBFs with ductility-enhanced joints were established, and the accuracy of the numerical model was verified. Secondly, the incremental dynamic analysis method was used to analyze the influence of the global ductility on the seismic collapse capacity resistance of the structural systems. Finally, the seismic collapse capacity of the structural system was evaluated based on the Collapse Margin Ratio (CMR). The results show that, compared to the BRBFs with rigid connections, the global ductility of BRBFs with the Reduced Beam Section (RBS) connections and the Top-Flange Beam Splice (TFBS) connections increase gradually. The CMR and the seismic collapse resistance capacity of BRBFs are improved with the increment of structural global ductility.

Shear Capacity Prediction for RC Beams Without Stirrups Based on Mechanical Research



XIONG Ergang, ZU Kun, HU Qinbin, et al

2022, 50(11):  115-124.  doi:10.12141/j.issn.1000-565X.210217

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Starting from the critical failure inclined section of reinforced concrete beam without stirrups, this study analyzed the force of each part on the critical failure inclined section. Through theoretical derivation and rational simplification, the value of calculation parameters was obtained, and the calculation model of shear capacity of based on mechanical balance for the reinforced concrete beam without stirrups. On the basis of the classical mechanics principle, the model has a clear physical meaning and can better reflect the influences of shear parameters including concrete strength, shear-span ratio, longitudinal reinforcement ratio and size effect, respectively. Then, the prediction accuracy and stability of the proposed shear model were evaluated based on 9 test specimens by comparing with the GB 50010—2010, ACI 318-14, EC 2, JSCE 2007 and Zsutty calculation formula. Finally, the applicability of the proposed model in the calculation of shear capacity of FRP reinforced concrete beams without stirrups was verified. The results show that the proposed model based on mechanical balance can effectively predict the shear capacity of reinforced concrete beams without stirrups and exhibit the shear failure mechanism of beam oblique section. Moreover, the proposed shear model has a higher prediction accuracy and stability, and can better reflect the nonlinear relationship between shear capacity versus shear-span ratio and longitudinal reinforcement ratio. In addition, the predicted results have a consistent stability with the change of shear parameters, so it can be applied to the shear capacity calculation of FRP reinforced concrete beams without stirrups.

Strength Prediction of Foam Light Soil Based on GA-BP Neural Network



ZHOU Zhong, DENG Zhuoxiang, CHEN Yun, et al

2022, 50(11):  125-132.  doi:10.12141/j.issn.1000-565X.220139

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Compressive strength is an important mechanical property of foamed lightweight soil. Accurately predicting and adjusting the compressive strength of lightweight foam soil is of great practical significance for improving construction efficiency. For intelligent control and optimization of foam light soil, this study designed a topology structure including 4 node input layer, 8 node hidden layer and 1 node output layer. The weight and threshold of BP neural network were improved by genetic algorithm (GA) in input layer. Using the four parameters of water-solid ratio, fly-ash ratio, fine aggregate mixing ratio and bubble rate as input parameters and 28-day compressive strength as output parameters, the two models before and after optimisation were validated and compared using mean squared error (MSE), coefficient of determination (R2) and relative error as samples. Based on this, a method for designing the mix ratio based on different performance requirements was established. The results show that compared with BP neural network, the GA-BP neural network has a larger fitness function value and smaller mean square deviation; the fit between the predicted and actual values can reach 0.946, with stronger prediction accuracy and gene-ralization ability; the global search ability of the genetic algorithm also makes up for the defect that BP neural network can easily fall into local optimum, and can better guide the fitting ratio design of the strength prediction of fly ash foam lightweight soil. The GA-BP neural network based strength growth prediction model for foam lightweight soils enables flexible adjustment of the compressive strength of foam lightweight soils, and it is of important refe-rence value for engineering construction.

Prestress Optimization of Cable Domes with Plant Growth Simulation Algorithm Based on Stage Growth



JIANG Zhengrong, SU Yan, SHI Kairong, et al

2022, 50(11):  133-140.  doi:10.12141/j.issn.1000-565X.210684

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In order to seek a reasonable and efficient prestress optimization method for cable domes, this paper proposed a new strategy for growth diffusion mechanism of large step and screening mechanism of growth points by analyzing the basic principle and algorithm mechanism of plant growth simulation algorithm (PGSA). On this basis, the plant growth simulation algorithm based on stage growth (stage growth PGSA) was established. This algorithm divides the optimization process into multiple stages and introduces the corresponding growth diffusion mechanism or screening mechanism of growth points in different stages. Firstly, the growth diffusion mechanism of large step was introduced to realize the spread of growth points by means of one-time diffusion growth with multiple steps. Then, the fast search was carried out with the medium step and the loose screening mechanism. Finally, the convergence was conducted with the small step for accuracy requirements and the strict screening mechanism. Thus, the prestress optimization of cable domes was done by using the stage growth PGSA and compared with other algorithms. The results show that the stage growth PGSA can effectively improve the global searching ability, reduce the growth space, and avoid growth points becoming saturated compared with the original PGSA. The number of calculation iteration of stage growth PGSA is the smallest and the initial strain energy of the structure after optimization is minimal in comparison with those of the multi-island genetic algorithm, adaptive simulated annealing algorithm, and particle swarm optimization algorithm. With its higher optimization efficiency and better optimization effect, therefore, this algorithm is applicable to the prestress optimization of cable domes.

Influence of Eccentricity on Induced Anisotropy of Granular Media



ZHOU Xiaowen, XU Yanbin, ZHAO Shiwei, et al

2022, 50(11):  141-154.  doi:10.12141/j.issn.1000-565X.210747

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There is a close cross-scale relationship between fabric anisotropy of granular media and the macro-mechanical properties, and particle shape plays a significant role in the evolution of the fabric anisotropy. In addition to sphericity, angularity and roughness of particles, the authors found that the eccentricity in the particle morphology is also an important factor, and there were few studies on it so far. So in this paper, the open source aspheric DEM program SudoDEM was used to model eccentric particles based on poly-superellipsoids. A series of true triaxial simulations with different eccentricities were carried out, and the effects of eccentricity on the induced anisotropy of granular media were explored. The results show that the fabric anisotropy develops to varying degrees with the increase of eccentricity, leading to the development of macroscopic shear resistance of granular media. Meanwhile, the coordination number is larger, the proportion of sliding contacts is higher, and the grid inhomogeneity of the contact force is more obvious. This is mainly because the particle eccentricity enhances the interlocking between particles. Normal contact force has the largest weight in the induced anisotropy, while the normal branch vector remains basically isotropic. Anisotropy of tangential contact force and tangential branch vector are rather sensitive to the eccentricity, indicating that contribution of them to fabric anisotropy cannot be ignored. The increased weak contact and sliding contact proportions caused by the increased eccentricity also indirectly lead to transformation between the normal contact force anisotropy and tangential contact force anisotropy.