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design equations for maximum stress concentration factors for concrete-filled steel tubular K-joints

Journal of Traffic and Transportation Engineering(English Edition) 2024年第05期 1001-1022页

作者： Lei Jiang Yongjian Liu Neil A.Hoult Xin Long Wenshuai Wang School of highway Chang'an University Department of Civil Engineering Queen's University CCCC second highway Consultants Co. Ltd. research and Development Center of Life Cycle BIM Technologies Application Shandong Provincial Communications Planning and Design Institute Group Co.Ltd.

Stress concentration factors(SCFs) for welded tubular joints can be decreased by filling the chord with concrete leading to a longer fatigue life. However, there are currently no design formula available in guidelines to predict the SCF of concrete-filled circular hollow section(CFCHS) K-joints, thus limiting their applicability in bridge design. To address this gap,finite element models for CFCHS K-joints were developed and compared against test results to ensure their accuracy. Then, a comprehensive parametric study was conducted to establish relationships between maximum SCFs and four variables: brace-to-chord diameter ratio(β), chord diameter-to-thickness ratio(2.), brace-to-chord thickness ratio(τ), and the angle between braces and chord(θ). A total of 480 FE models were examined under three loading conditions including brace and chord loading: balanced axial force, chord axial force, and chord bending. design equations to predict the maximum SCF for CFCHS Kjoints were established by multiple regression analyses of the numerical results. A comparison of maximum SCFs between circular hollow section(CHS) and CFCHS K-joints was made, and it was concluded that average reductions of 42. and 33% in maximum SCFs in CFCHS K-joints at the locations of the chord and brace were found compared to CHS joints for balanced axial force, respectively. Finally, a case study illustrating how to use the proposed equations for fatigue safety verification was presented.

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New method to identify optimal discontinuity set number of rock tunnel excavation face orientation based on Fisher mixed evaluation

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Underground Space 2024年第4期17卷 300-319页

作者： Keshen Zhang Wei Wu Min Zhang Yongsheng Liu Yong Huang Baolin Chen College of Civil Engineering Tongji UniversityShanghai 200092China Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji UniversityShanghai 200092China State Key Laboratory of Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China Shudao Investment Group Co.Ltd Chengdu 610095China china Railway Tunnel Group Co.Ltd Guangzhou 511466China china Railway First survey and {2. institute Group Co.Ltd Xi’an 710043China Zhejiang institute of communications Co.Ltd Hangzhou 310012China

Discontinuity is critical for strength,deformability,and permeability of rock *** information is one of the essential discontinuity characteristics and is usually accessed by orientation *** methods of identifying optimal discontinuity set numbers are usually achieved by clustering validity indexes,which mainly relies on the aggregation and dispersion of clusters and leads to the inaccuracy and instability of *** paper proposes a new method of Fisher mixed evaluation(FME)to identify optimal group numbers of rock mass discontinuity *** FME,orientation distribution is regarded as the superposition of Fisher mixed *** grouping results are identified by considering the fitting accuracy of Fisher mixed distributions,the probability monopoly and central location significance of independent Fisher centers.A Halley-Expectation-Maximization(EM)algorithm is derived to achieve an automatic fitting of Fisher mixed *** real rock discontinuity models combined with three orientation clustering algorithms are adopted for discontinuity *** clustering validity indexes are used to automatically identify optimal group numbers for *** results show that FME is more accurate and robust than the other clustering validity indexes in optimal discontinuity group number identification for different rock models and orientation clustering algorithms.

关键词： Rock mass discontinuity Orientation grouping Fisher mixed distribution 3D point cloud Stereo photogrammetry

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Theory and practice concerning classification for expansive soils using standard moisture absorption water content

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Science china(Technological Sciences) 2005年第1期48卷 31-40页

作者： YAO Hailin1, CHENG Ping2. YANG Yang1 & WU Wanping2.1. institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, china {2., Wuhan 430052. china 1. institute of Rock and Soil Mechanics Chinese Academy of Sciences 430071 Wuhan China 2. china communications second highway survey design and research institute 430052 Wuhan China

A series of tests on physical, mechanical and chemical properties of expansive soils have shown that the standard moisture absorption water content (SMA) of expansive soils has a good linear relationship with montmorillonite content, cation exchange capacity, specific surface, and it also presents a linear relationship tendency to plastic index and free swell ratio. All this indicates that the above SMA is of clear significance in physics. The plastic index can better reflect the interaction extent between composition and dispersing character of grains, cation and clay minerals. Consequently, SMA can reflect the basic essential properties of expansive soils. On the basis of the classification results that have been published in literature and in consideration of the succession to the classification results for the free swell ratio, this paper puts forward three indexes, i.e. the SMA, plastic index and free swell ratio to classify expansive soils. The tests proposed for the classification indexes are easy to operate, simple in testing device and last a short time. Compared with the latest issued “Classification Standard Code for Rocks and Soils of Railway Projects” (TB10077-2.01), the method proposed in this paper is more convenient and reasonable, and can be popularized, when environment conditions ripen, for the application in field of exploration and design of highway in the areas surrounded by expansive soils.

关键词： expansive soil, standard moisture absorption water content (SMA), plasticity index, free expansive ratio, identification and classification of expansive soils.

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Quantification constraints on time gap for comagmatic gold deposits:Evidence from chronological statistics

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Chinese Journal Of Geochemistry 2008年第4期27卷 325-334页

作者： TAN Jun WEI Junhao LI Shuiru ZHANG Chunhua LI Yanjun GUO Lingli YAN Yunfei Faculty of Earth Resources China University ofGeosciences Wuhan 430074 China Guangxi Geological survey institute Nanning 530023 China china communications {2. highway survey Design andResearch Institute Wuhan 430056 China

The time gap between diagenesis and mineralization (TGDM) for comagmatic gold deposits (CGD) plays an important role in confirming the genetic relationship between gold deposits and their related intrusions. With the help of preciously published isotopic ages of some typical gold deposits and their related rocks in china,the authors have discussed and quantified the distribution characteristics and scope of the TGDM. Statistical analyses and Kolmogorov tests showed that mineralizing events are either contemporaneous with or slightly postdate their cognate magma. The TGDM conforms with normal distributions at a 0.05 confidence level and clusters between 0 and 16.0 Ma with a mean of 7.0 Ma. Thus,if the TGDM of CGD is less than 16.0 Ma,it is reasonable to consider,with the aid of other evidence,the possibility of its comagmatic genetic affiliation. The authors also emphasized that to get a precise time gap it is necessary to strengthen the diagenesis-mineralization geological background of the deposits studied,and to pay attention to the study of time gap in combination with trace elements and isotope tracing.

关键词：黄金沉积时间间隙统计分析测试

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Analysis on Bearing Capacity of Tunnel-Type Anchorage of a Long-Span Suspension Bridge

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Journal of china University of Geosciences 2005年第3期16卷 277-282页

作者： Zhu Yu Wei Jun Yang Manjuan Li Hao Liu Hongqing School of Civil Engineering and Mechanics Huazhong University of Science and Technology Wuhan 430074 China china communications {2. highway survey design and research institute Wuhan 430052 China

Due to complicated rock structure and environment, a prototype test for a tunnel-type anchorage is infeasible. Based on the rock mass parameters from tests, a three-dimensional （3D） elastoplastic analysis was performed to simulate the influence of the construction procedure of Siduhe bridge with tunnel-type anchorage （TTA） in Hubei Province, china. The surrounding rock and concrete anchorage body were simulated by 8 nodes 3D brick elements. The geostatic state of the complex geometric structure was established with initial data. The in-situ concrete casting of the anchorage body and excavation of the rock mass were simulated by tetrahedral shell elements. The results show that the surrounding rock is in an elastic state under the designed cable force. The numerical overloading analysis indicates that the capacity of the surrounding anchorage is 7 times that of the designed cable force. The failure pattern shows that two anchorage bodies would be pulled out in the end. The maximum shear stress appears 10 m before the back anchorage face. The maximum range influenced by the TTA under ultimate loads is about 16 m.

关键词： tunnel-type anchorage suspension bridge elasto-plastic analysis bearing capacity

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Hybrid Simulation of the Initiation and Runout Characteristics of a Catastrophic Debris Flow

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Journal of Mountain Science 2013年第2期10卷 219-232页

作者： CHEN Hong-Xin ZHANG Li-Min ZHANG Shuai XIANG Bo WANG Xiao-Feng Department of Civil and Environmental Engineering The Hong Kong University of Science and Technology highway Planning SurveyDesign and Research InstituteSichuan Province Communications Department

On 13 August 2.10, a catastrophic debris flow with a volume of 1.17 million m3 occurred in Xiaojiagou Ravine near Yingxiu town of Wenchuan county in Sichuan Province, china. The main source material was the landslide deposits retained in the ravine during the 2.08 Wenchuan earthquake. This paper describes a two-dimensional hybrid numerical method that simulates the entire process of the debris flow from initiation to transportation and finally to deposition. The study area is discretized into a grid of square zones. A two dimensional finite difference method is then applied to simulate the rainfall-runoff and debris flow runout processes. The analysis is divided into three steps; namely, rainfall-runoff simulation, mixing water and solid materials, and debris flow runout simulation. The rainfall-runoff simulation is firstly conducted to obtain the cumulative runoff near the location of main source material and at the outlet of the first branch. The water and solid materials are then mixed to create an inflow hydrograph for the debris flow runout simulation. The occurrence time and volume of the debris flow can be estimated in this step. Finally the runout process of the debris flow is simulated. When the yield stress is high, it controls the deposition zone. When the yield stress is medium or low, both yield stress and viscosity influence the deposition zone. The flow velocity is largely influenced by the viscosity. The estimated yield stress by the equation, ty = pghsinO, and the estimated viscosity by the equation established by Bisantino et al. （2.10） provide good estimates of the area of the debris flow fan and the distribution of deposition depth.

关键词： Debris flow Landslide Rain-inducedlandslide Surface runoff Runout distance Wenchuan earthquake Numerical simulation

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A Combined-Power Model for the Distribution of Axial Force in Shaft Anchor along Its Length

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Journal of china University of Geosciences 2006年第1期17卷 89-94页

作者：卫军周锡武朱玉罗昕 Civil Engineering Department Huazhong University of Science and Technology Wuhan430074 China Civil Engineering Department Huazhong University of Science and Technology Wuhan430074 ChinaChina Communications Second Highway Survey Design and Research Institute Wuhan430052 China

The theoretical results of axial force distribution models differ greatly from tests because of the complication of the rock type material. A three-parameter combined-power model is proposed by curves fitting the test data recorded from the pull tests on anchoring bars used in different engineering projects. Based on the comparison of the mechanical characteristics of shaft anchors and prestressed tendons, a two-parameter combined-power function model for prestressed tendons is proposed. The bounded length derived from the model and the suggested values of the parameters are also proposed. Compared with the Gaussian model, the three-parameter combined-power model is more precise and simple in expression. Results also suggest that the bounded length calculated from the average stress method is not safe enough.

关键词： axial force prestress tendon bounded length combined-power model Gaussian model

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Comparison of LR,5-CV SVM,GA SVM,and PSO SVM for landslide susceptibility assessment in Tibetan Plateau area,china

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Journal of Mountain Science 2023年第4期20卷 979-995页

作者： ZHANG Ying-bin XU Pei-yi LIU Jing HE Jian-xian YANG Hao-tian ZENG Ying HE Yun-yong YANG Chang-feng Department of Geotechnical Engineering School of Civil EngineeringSouthwest Jiaotong UniversityChengdu610031China Sichuan highway Planning SurveyDesign and Research Institute Ltd.Chengdu610041China

The applicability of statistics-based landslide susceptibility assessment methods is affected by the number of historical *** studies have proposed support vector machine(SVM)as a small-sample learning ***,those studies demonstrated that different parameters can affect model *** optimized the SVM and obtained models as 5-fold cross validation(5-CV)SVM,genetic algorithm(GA)SVM,and particle swarm optimization(PSO)*** study compared the prediction performances of logistic regression(LR),5-CV SVM,GA SVM,and PSO SVM on landslide susceptibility mapping,to explore the spatial distribution of landslide susceptibility in the study area in Tibetan Plateau,china.A geospatial database was established based on 392.historical landslides and 392.non-landslides in the study *** used 11 influencing factors of altitude,slope,aspect,curvature,lithology,normalized difference vegetation index(NDVI),distance to road,distance to river,distance to fault,peak ground acceleration(PGA),and rainfall to construct an influencing factor evaluation *** evaluate the models,four susceptibility maps were compared via receiver operating characteristics(ROC)curve and the results showed that prediction rates for the models are 84%(LR),87%(5-CV SVM),85%(GA SVM),and 90%(PSO SVM).We also used precision,recall,F1-score and accuracy to assess the quality performance of these *** results showed that the PSO SVM had greater potential for future implementation in the Tibetan Plateau area because of its superior performance in the landslide susceptibility assessment.

关键词： Tibetan Plateau area Logistic regression Support vector machine Landslide susceptibility assessment

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Effects of initial particle gradation and rock content on crushing behaviors of weathered phyllite fills——A case of eastern Ankang section of Shiyan—Tianshui highway,china

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第2期12卷 269-278页

作者： Feifei Liu Xuesong Mao Yushuo Fan Linping Wu Wei Victor Liu School of highway Chang'an UniversityXi'anChina Shijiazhuang Transportation survey and design {2. ShijiazhuangChina Department of Civil and Environmental Engineering University of AlbertaEdmontonCanada

The objective of this paper is to investigate the effects of initial particle gradation and rock content on the crushing behavior(*** size before and after crushing) of weathered phyllite *** tests were conducted on weathered phyllite fills with rock contents of 35%,45%,55%,65% and 75%(by weight).First,the particle size distributions(PSDs) were observed before and after compaction,and then the particle breakage of weathered phyllite fills was analyzed by fractal *** fractal dimension was proposed to evaluate the effects of initial rock content and initial gradation on the particle *** was found that the fractal dimension method can well characterize the crushing behaviors of the weathered phyllite *** finer the fills were,the more they were *** is,after the first compaction,the relative fractal dimension of the weathered phyllite fills increased as the rock content increased,reaching the values of 0.013,0.016,0.02.,0.037 and 0.08,*** the second compaction,these relative fractal dimension values,dominated by the initial particle gradation,became 0.059,0.072.0.052.0.095 and 0.118,*** conclusion,the weathered phyllite fills with 55% rock content exhibited the least breakage and were most suitable for filling the *** in this paper will provide significant guidance for the construction of weathered phyllite filling subgrade in future projects.

关键词： Weathered phyllite fills Crushing behavior Compaction test Fractal dimension Relative fractal dimension

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Mechanism of evolution on wintertime natural convection cooling effect of frac-tured-rock embankment in permafrost regions

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Chinese Science Bulletin 2005年第23期50卷 2744-2754页

作者： SUN Binxiang XU Xuezu LAI Yuanming WANG Shuangjie ZHANG Jinzhao Department of Civil Engineering Shaoxing College of Arts and Sciences. Shaoxing 312000 China State Key Laboratory of Frozen Soil Engineering Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China The First highway survey & {2. institute Ministry of Communications Xi'an 710068 China

Mechanism and evolution of the pore-air natu-ral convection cooling effect in fractured-rock embankmentsin permafrost regions are studied using a numerical repre-sentation of the non-dimensional governing equations in variable permeability porous media. The analyses show that winter-time natural convection in fractured-rock embank-ments begins to occur in the side slope portions and gradu-ally develops from the left and right side slope portions to themiddle portion of embankment. The more significant distor-tion of isotherms from their initial orientations due to heat conduction alone is that the cooling effect of winter-time natural convection on the fractured-rock embankment is stronger. The minimum critical Rayleigh numbers triggering natural convection of the pore-air in the side slope portions and the middle portion of embankment were obtained. The factors of influence on triggering winter-time convection cooling effect in fractured-rock embankments were analyzed. Finally, the assertion that the techniques of the frac-tured-rock revetment and berm are the effective measures to maintain the heat stability of the roadbed in permafrost re-gions is theoretically demonstrated.

关键词：永久冻土区青藏高原气候变暖破碎岩石路基自然对流冷却冬季

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