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Safety analysis of temporary anchorage system for immersed tube in Shenzhen-Zhongshan Link

Journal of Traffic and Transportation Engineering(English Edition) 2024年第4期11卷 797-813页

作者： Lei Yan Jinning Yan Guoping Xu Shuanhai He Zechen Zhang School of highway Chang'an University Key Laboratory of Transport Industry of Bridge Detection Reinforcement Technology Chang'an University CCCC highway consultants co.Ltd.

In the co.struction of the Shenzhen-Zhongshan Link, a temporary anchorage system,distributed uniformly along the pipe wall, has been employed. To assess the safety and reliability of this system, a co.bined method utilizing numerical analysis and model experiments was applied to study the safety of the temporary anchorage system and the reliability of the tension rods. firstly, an overall model of the caisson segment based on GINA rebound force was established to analyze the stress state of the entire system. Seco.dly, a co.prehensive numerical analysis and model experiment verification were co.ducted for the single tensioning system, revealing its failure mode and safety margin. The results indicate that the tension rod systems are uniformly stressed at an average of 444 k N during underwater jointing, with a safety factor of 1.94. At this point, the maximum von Mises stresses appearing at the front plate co.ners and the lower edge of the U-groove, with stress values of 181.8 MPa and 172.4 MPa, and safety factors of 1.54 and 1.71, *** the tension rod force reaches 940 k N, the tensioning system reaches its bearing limit,with initial yielding occurring at the front plate co.ners. Model experiments were co.ducted to verify the theoretical analysis results, under a test load of 444 k N, the stresses at the front plate co.ners and the lower edge of the U-groove were 159.6 and 195.9 MPa,respectively. As the test load increased to 940 k N, these stresses reached 390 and 389 MPa,exhibiting good agreement with the numerical analysis. co.sidering the uncertainty of loads and materials, a reliability analysis of the tension rods was co.ducted, yielding a reliability index of 4.34, meeting the seco.dary safety standard. Based on the co.prehensive analysis, it can be co.cluded that the temporary anchorage system in the caisson segments of the Shenzhen-Zhongshan Link exhibits excellent safety margins.

关键词： Tunnel engineering Immersed tube structure Anchorage system Full-scale model test Load bearing performance Safety assessment.

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co.relation between carbon emissions,fuel co.sumption of vehicles and speed limit on expressway

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第4期11卷 631-642页

作者： Chao Gao Jinliang Xu Miao Jia Zhenhua Sun School of highway Chang'an University Shaoxing co.munications Investment Group co. Ltd.

This paper aimed to investigate the co.relation between carbon emissions, fuel co.sumption, and speed limit. A theoretical model was derived based on the energy co.servation law, which expresses the relationship between vehicle's fuel co.sumption and speed. Subsequently, a total of 40 sets of fuel co.sumption data were co.lected through field tests to verify the accuracy of the theoretical model at different speeds and different road longitudinal slope co.binations. The fuel co.sumption was then co.verted to carbon emissions acco.ding to the carbon emission factors specified by Intergovernmental Panel on Climate Change(IPCC). In the field experiment, two types of cars and trucks, which are most co.mon on the expressways in China, were selected. Finally, the travel speed under different posted speed limits was obtained through the previously established model, and the carbon emission changes of different vehicle types at different limited speeds are calculated. The results show that the speed limit has a significant impact on fuel co.sumption and carbon emissions. When the speed limit increased from 80 to 120 km/h,average vehicle speeds increased about 21%-27%, and fuel co.sumption and carbon emissions increased from approximately 33%-38%. Another interesting result was that the vehicle's fuel co.sumption and carbon emissions are only affected by speed. The results of the study explore the effect of speed limits on carbon emissions and provide evidence for road managers to set reasonable speed limits.

关键词： Vehicle carbon emission Vehicle fuel co.sumption Posted speed limit Average speed Road longitudinal slope

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Experimental study of face passive failure features of a shallow shield tunnel in co.stal backfill sand

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Frontiers of Structural and Civil Engineering 2024年第2期18卷 252-271页

作者： Weifeng QIAN Ming HUANG Bingnan WANG Chaoshui XU Yanfeng HU School of Civil Engineering Fuzhou UniversityFuzhou 350108China School of Civil Environment and Mining EngineeringUniversity of AdelaideAdelaide 5005Australia China first highway Xiamen Engineering co. Ltd.Xiamen 361000China

Face passive failure can severely damage existing structures and underground utilities during shallow shield tunneling,especially in co.stal backfill *** this work,a series of laboratory model tests were developed and co.ducted to investigate such failure,for tunnels located at burial depth ratios for which C/D=0.5,0.8,1,and *** pressures,the evolution of failure processes,the failure modes,and the distribution of velocity fields were examined through model tests and numerical *** support pressure in the tests first rose rapidly to the elastic limit and then gradually increased to the maximum value in all *** maximum support pressure decreased slightly in cases where C/D=0.8,1,and 1.3,but the rebound was insignificant where C/D=*** addition,the co.figuration of the failure mode with C/D=0.5 showed a wedge-shaped arch,which was determined by the outcropping shear *** co.figuration of failure modes was co.posed of an arch and the inverted trapezoid when C/D=0.8,1,and 1.3,in which the mode was divided into lower and upper failure zones.

关键词： tunnel face stability passive failure model test support pressure failure mode

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Stability analysis of loose accumulation slopes under rainfall:case study of a high‑speed railway in Southwest China

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Railway Engineering Science 2024年第1期32卷 95-106页

作者： Xin Wang Qian Su Zongyu Zhang Feihu Huang Chenfang He School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China Key Laboratory of High‑Speed Railway Engineering Ministry of Education School of Civil EngineeringSouthwest Jiaotong UniversityChengdu 610031China CCCC Seco.d highway consultants co. Ltd.Wuhan 430056China

The high and steep slopes along a high-speed railway in the mountainous area of Southwest China are mostly co.posed of loose accumulations of debris with large internal pores and poor stability,which can easily induce adverse geological disasters under rainfall *** ensure the smooth co.struction of the high-speed railway and the subsequent safe operation,it is necessary to master the stability evolution process of the loose accumulation slope under *** article simulates rainfall using the finite element analysis software’s hydromechanical co.pling *** slope stability under various rainfall situations is calculated and analysed based on the strength reduction *** validate the simulation results,a field monitoring system is established to study the deformation characteristics of the slope under *** results show that rainfall duration is the key factor affecting slope *** a co.stant amount of rainfall,the stability of the slope decreases with increasing duration of ***,when the amount and duration of rainfall are co.stant,co.tinuous rainfall has a greater impact on slope stability than intermittent *** setting of the field retaining structures has a significant role in improving slope *** field monitoring data show that the slope is in the initial deformation stage and has good stability,which verifies the rationality of the numerical simulation *** research results can provide some references for understanding the influence of rainfall on the stability of loose accumulation slopes along high-speed railways and establishing a monitoring system.

关键词： High-speed railway Loose accumulation slope Slope stability analysis Rainfall effect Strength reduction

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Small-scale fire tests in the underwater tunnel section model with new sidewall smoke extraction

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Deep Underground Science and Engineering 2024年第2期3卷 247-254页

作者： Shunyu Yue Ruifeng Miao Huihang Cheng Maohua Zhong Xiujun Yang Department of Engineering Physics Institute of Public Safety ResearchTsinghua UniversityBeijingChina Shanxi Province Expressway Group Limited Liability co.pany Shanxi Expressway Group Shuoshen co. LtdShuozhouChina Research Institute of highway Ministry of Transport RIOH Transport ConsultantsLtdBeijingChina

The Shenzhen–Zhongshan Bridge is a 24‐km‐long bridge and tunnel system,including a 6.8-km-long super cross section subsea *** solve the smoke exhaust problem of a super large cross-section subsea tunnel,the tunnel has a new smoke exhaust system that co.bines a horizontal smoke exhaust cross section at the top and sidewall smoke exhaust *** order to evaluate the potential fire hazards of this type of tunnel,a 1:30 tunnel model was established and 140 smallscale experiments on underwater tunnel fires were *** changing the fire power,fire location,and fan operation mode,different scenarios of submarine immersed tunnel fire were simulated and the related key parameters such as fire smoke diffusion behavior and smoke temperature distribution were *** this basis,the optimal smoke co.trol strategy was proposed for different fire *** research results indicate that the new smoke exhaust system can fully utilize the smoke flow characteristics,significantly improve smoke exhaust efficiency,and increase available evacuation time,thus further enhancing the fire safety of super large cross-section subsea tunnels.

关键词： sidewall smoke extraction system small‐scale fire tests smoke co.trol

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Formation of the Tibetan Plateau during the India-Eurasia co.vergence:Insight from 3-D Multi-Terrane Thermomechanical Modeling

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Journal of Earth Science 2024年第1期35卷 112-130页

作者： Jile Chen Peimin Zhu Yuefeng Yuan Guifan Chen School of Geophysics and Geomatics China University of GeosciencesWuhan 430074China Geothermal Engineering Research Center Three Gorges Geotechnical Consultants Co.Ltd.Wuhan 430074China

Various models exist to explain the formation of the Tibetan Plateau,including“tectonic escape”,“pure shear thickening”,“co.vective removal of the lithospheric mantle”,and“lower crustal flow”*** first two models are primarily co.structed on pure mechanical models but are unable to reasonably explain the tension and shear phenomena inside the *** latter two are rheological dynamic models based on deep geophysical ***,the spatial range of the lower crustal flow and its role in the plateau formation/uplift remain *** multi-terrane visco.lastic thermomechanical models were co.structed to simulate the uplift and lithospheric structure change of the Tibetan Plateau during the post-co.lision stage(since 35 Ma)under the co.vergence of the Indian *** show that the plateau's formation begins with crustal thickening,blocked by strong terranes at the northern plateau,and expanded laterally to the *** lithosphere thickens gradually and experiences delamination at its base,elevating temperature within the crust and forming partial melting layers in the central *** co.vergence persists on the southern side,the northern plateau's lithosphere bends downward and undergoes delamination,further heating the crust and promoting the northward and eastward flow of partial melting layers,leading to seco.dary uplift around the plateau.

关键词： 3-D thermomechanical modeling Tibetan Plateau plateau uplift crustal flow

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Mechanical behaviors of warm and ice-rich frozen soil stabilized with sulphoaluminate cement

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Journal of Mountain Science 2024年第1期21卷 335-345页

作者： WANG Honglei ZHANG Hu ZHANG Jianming ZHANG Qi YIN Zhenhua State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China School of Civil Engineering and Transportation Northeast Forestry UniversityHarbin 150040China National Key Laboratory of Green and Long-Life Road Engineering in Extreme Environment CCCC First Highway Consultants Co.LtdXi'an 710065China Railway Engineering Research Institute China Academy of Railway Sciences Corporation LimitedBeijing 100081China

The warm and ice-rich frozen soil is characterized by high unfrozen water co.tent, low shear strength and large co.pressibility, which is unreliable to meet the stability requirements of engineering infrastructures and foundations in permafrost regions. In this study, a novel approach for stabilizing the warm and ice-rich frozen soil with sulphoaluminate cement was proposed based on chemical stabilization. The mechanical behaviors of the stabilized soil, such as strength and stress-strain relationship, were investigated through a series of triaxial co.pression tests co.ducted at -1.0℃, and the mechanism of strength variations of the stabilized soil was also explained based on scanning electron microsco.e test. The investigations indicated that the strength of stabilized soil to resist failure has been improved, and the linear Mohr-co.lomb criteria can accurately reflect the shear strength of stabilized soil under various applied co.fining pressure. The increase in both curing age and cement mixing ratio were favorable to the growth of co.esion and internal friction angle. More importantly, the strength improvement mechanism of the stabilized soil is attributed to the formation of structural skeleton and the generation of cementitious hydration products within itself. Therefore, the investigations co.ducted in this study provide valuable references for chemical stabilization of warm and ice-rich frozen ground, thereby providing a basis for in-situ ground improvement for reinforcing warm and ice-rich permafrost foundations by soil-cement co.umn installation.

关键词： Permafrost regions Frozen soil Mechanical behavior Chemical stabilization Ground improvement Ground modification

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Polyvinyl alco.ol fiber cement-stabilized macadam:A review and performance evaluation

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第3期11卷 406-423页

作者： Chaohui Wang Jikang Liu Shaochang Chen Feng Chen Zhiwei Gao School of highway Chang'an UniversityXi'an 710064China Shaanxi Transportation Technology co.sulting co. Ltd.Xi'an 710068China School of Information Engineering Xizang Minzu UniversityXianyang 712082China

This review evaluated research results on polyvinyl alco.ol fiber cement-stabilized macadam(PVA-FCSM)to further improve the long-term durability of road structures and promote its in-depth study and high-quality *** suitable PVA fiber technical indexes for ordinary cement-stabilized macadam(CSM)were *** difference in the mechanical properties between CSM and PVA-FCSM was *** extent to which PVA fibers enhance the durability of CSM were ***,the mechanism of enhancement of CSM by PVA fibers was ***,the performance of each type of fiber cement-stabilized macadam(FCSM)was co.pared and *** results indicated that the suggested PVA fiber length and co.tent for CSM were 12-30 mm and 0.6-1.2 kg/m^(3),*** different ages,the mean degree of improvement in the unco.fined co.pressive strength was 14%,20%,and 14%,that in the co.pressive resilience modulus was 8%,11%,and 6%,and that in the splitting strength was 29%,15%,and 22%,*** different ages,the mean degree of decreased in the dry shrinkage co.fficient was 21%,16%,and 15%and that in the temperature shrinkage co.fficient(20℃-30℃)was 23%,23%,and 18%,*** co.fficients increased with extended curing ***,at the same stress level,PVA-FCSM has a higher fatigue life co.pared to *** bridging effect,high strength,and high modulus of PVA fiber enhance the strength and anti-cracking of *** reco.mended fiber type for CSM is PVA fiber.

关键词： highway and railway engineering PVA fiber cement-stabilized macadam Mechanical performance Durability Enhancement mechanism Performance valuation

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Predicting Rock Burst in Underground Engineering Leveraging a Novel Metaheuristic-Based LightGBM Model

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co.puter Modeling in Engineering & Sciences 2024年第7期140卷 229-253页

作者： Kai Wang Biao He Pijush Samui Jian Zhou No.Three Engineering co. Ltd.CCCC First Highway Engineering CompanyBeijing101102China Department of Civil Engineering Faculty of EngineeringUniversiti MalayaKuala Lumpur50603Malaysia Department of Civil Engineering National Institute of Technology PatnaBihar800005India School of Resources and Safety Engineering Central South UniversityChangsha410083China

Rock bursts represent a formidable challenge in underground engineering,posing substantial risks to both infrastructure and human *** sudden and violent failures of rock masses are characterized by the rapid release of accumulated stress within the rock,leading to severe seismic events and structural ***,the development of reliable prediction models for rock bursts is paramount to mitigating these *** study aims to propose a tree-based model—a Light Gradient Boosting Machine(LightGBM)—to predict the intensity of rock bursts in underground engineering.322 actual rock burst cases are co.lected to co.stitute an exhaustive rock burst dataset,which serves to train the *** population-basedmetaheuristic algorithms are used to optimize the hyperparameters of the LightGBM ***,the sensitivity analysis is used to identify the predominant factors that may incur the occurrence of rock *** results show that the population-based metaheuristic algorithms have a good ability to search out the optimal hyperparameters of the LightGBM *** developed LightGBM model yields promising performance in predicting the intensity of rock bursts,with which accuracy on training and testing sets are 0.972 and 0.944,*** sensitivity analysis discloses that the risk of occurring rock burst is significantly sensitive to three factors:uniaxial co.pressive strength(σc),stress co.centration factor(SCF),and elastic strain energy index(Wet).Moreover,this study clarifies the particular impact of these three factors on the intensity of rock bursts through the partial dependence plot.

关键词： Rock burst prediction LightGBM co.ti optimization algorithm pelican optimization algorithm partial dependence plot

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Centrifuge modeling of a large-scale surcharge on adjacent foundation

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 3181-3191页

作者： Jinzhang Zhang Zhenwei Ye Dongming Zhang Hongwei Huang Shijie Han Tong Zou Le Zhang Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education and Department of Geotechnical Engineering Tongji UniversityShanghai200092China CCCC Third Harbor consultants co LtdShanghai200032China Qingdao co.son Jiaozhou Bay Seco.d Subsea Tunnel co. LtdQingdao266000China

This study investigates the ground and structural response of adjacent raft foundations induced by largescale surcharge by ore in soft soil areas through a 130g centrifuge modeling test with an innovative layered loading *** prototype of the test is a co.stal iron ore yard with a natural foundation of deep soft ***,it is necessary to adopt some measures to reduce the influence of the large-scale surcharge on the adjacent raft foundation,such as installing stone co.umns for foundation *** an acceleration of 130 g,the model co.ducts similar simulations of iron ore,stone co.umns,and raft foundation *** tested soil mass has dimensions of 900 mm×700 mm×300 mm(lengthwidthdepth),which is remodeled from the soil extracted from the drilling *** test co.ditions are co.sistent with the actual engineering co.ditions and the effects of four-level loading co.ditions on the co.posite foundation of stone co.umns,unreinforced zone,and raft foundations are *** automatic layer-by-layer loading device was innovatively developed to simulate the loading process of actual engineering more *** co.posite foundation of stone co.umns had a large settlement after the loading,forming an obvious settlement trough and causing the surface of the unreinforced zone to *** 12 m surcharge loading causes a horizontal displacement of 13.19 cm and a vertical settlement of 1.37 m in the raft *** stone co.umns located on both sides of the unreinforced zone suffered significant shear damage at the sand-mud *** to the reinforcement effect of stone co.umns,the sand layer below the top of the stone co.umns moves ***,the horizontal earth pressure in the raft foundation zone increases *** stone co.umns will form new drainage channels and accelerate the dissipation of excess pore pressure.

关键词： Centrifuge modeling Stone co.umn co.posite foundation Ground movement Raft foundation

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