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Analysis of Calcined Red Mud Properties and Related Mortar Performances

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Fluid Dynamics & Materials Processing 2024年第5期20卷 901-913页

作者： Zhengfan Lyu Yulin Li Mengmeng Fan Yan Huang Chenguang Li Technical Center Office Guangxi Jiaojian Engineering Inspection Consulting Co.Ltd.Nanning530001China Technical Center Office Guangxi Road Construction Engineering Group Co.Ltd.Nanning530001China Nanning Road construction Technology and Road construction Materials Engineering Technology Research Centre Guangxi Road Construction Engineering Group Co.Ltd.Nanning530001China

Red mud(RM)is a low-activity industrial solid waste,and its utilization as a resource is currently a hot *** this study,the micro characteristics of red mud at different calcination temperatures were analyzed using X-ray diffraction and scanning electron *** performance of calcined red mud was determined through mortar strength *** indicate that high-temperature calcination can change the mineral co.position and microstructure of red mud,and increase the surface roughness and specific surface *** the optimal temperature of 700°C,the addition of calcined red mud still leads to a decrease in mortar strength,but its activity index and flexural co.fficient increase by 16.2%and 11.9%with respect to uncalcined red mud,reaching values of 0.826 and 0.974,*** with the co.trol group,the synergistic activation of calcined red mud with slag can increase the co.pressive and flexural strength of the mortar by 12.9%and 1.5%,reaching 8.7 and 62.4 MPa,***,the activity index and flexural co.fficient of the calcined RM and GGBS(Ground Granulated Blast furnace Slag)mixtures also increase to 1.015 and 1.130,respectively.

关键词： Red mud slag thermal activation synergistic activation mortar test microsco.ic properties

Hydration Behavior and Cementitious Properties of Calcium Carbonate-aluminate Minerals co.posite

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Journal of Wuhan University of Technology(Materials Science) 2024年第1期39卷 126-133页

作者：王冲周帅 ZOU Luyao LIU Jiawen ZHENG Yalin co.lege of Materials Science and Engineering Chongqing UniversityChongqing 400045China China West construction group co. Ltd.Chengdu 610015China

The purpose of this research is to investigate the hydration behavior and cementitious properties of the mixture of calcium carbonate and aluminate, and to explore whether it can be adopted as a new low-carbon cementitious material. The co.posite system of calcium carbonate and aluminate minerals is studied by measuring the co.ponent of hydration products, the hydration heat, setting time and co.pressive *** results prove that the co.posite system has certain cementitious properties and is feasible to prepare new low-carbon cement.

关键词： limestone hydrated calcium carboaluminate cementitious properties mechanical properties

Effect of the Retarder on Initial Hydration and Mechanical Properties of the"one-step"Alkaliactivated co.posite Cementitious Materials

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Journal of Wuhan University of Technology(Materials Science) 2024年第5期39卷 1199-1213页

作者： DING Rui HE Yue LI Xingchen LI Han TIAN Hao WANG Hongen School of Materials Science and Engineering Jilin Jianzhu UniversityChangchun 130118China Ziyang Urban construction Investment group co. LtdNanchong 637000China Shandong Taihe Urban construction Development co. Ltd.Jining 272000China

This paper studied the effects of different retarders on the performance of the"one-step"alkali-activated co.posite cementitious material(ACCM)which is co.posed of ground granulated blast slag(GGBS)and fly ash(FA),and analyzed its mechanical properties,hydration mechanism,and retardation *** effects of retarders on the hydration products,mechanical properties,and hydration kinetics of ACCM were investigated using XRD,SEM,FTIR,EDS,and thermoactive *** results showed that Na_(2)B_(4)O_(7)·10H_(2)O(B)delayed the exotherm during the alkali activation process and co.ld effectively delay the setting time of ACCM,but the mechanical properties were slightly *** setting time of ACCM increased with the increase in SG co.tent,but the mechanical properties of ACCM decreased with the increase in SG co.tent.C1_(2)H_(22)O_(11)(CHO)co.ld effectively delay the hydration reaction of ACCM and weakly enhanced the co.pressive strength.H_(3)PO_(4)(HP)at a co.centration of 0.05 mol/L had a certain effect on ACCM retardation,but HP at a co.centration of 0.07 and 0.09 mol/L had an effect of promoting the setting and hardening time of ACCM.

关键词： "one-step"alkali-activated co.posite cementitious materials solid activator hydration mechanism retarder retarding mechanism

Investigation and measurement of old building response to the overlapped shield tunnel of multiple schemes in the sandy co.ble stratum

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Underground Space 2024年第2期15卷 260-274页

作者： Xue Li Aopeng Geng School of Geoscience and Technology Southwest Petroleum UniversityChengduSichuan 610500China China Railway construction Bridge Engineering Bureau group co. Ltd.Tianjin 300300China

Ground movements due to tunneling are beco.ing increasingly critical as buildings are located around construction *** study proposes a new co.bined reinforcement method using a foundation grouting oblique pipe *** former improves the bearing capacity of the subsoil,and the latter blocks the transmission of soil deformation,which weakens the influence of construction during overlapped tunnel *** on this new method,a case study of the shield tunneling response to an old building in Line 6 of China’s Chengdu Metro is ***,three-dimensional numerical models without reinforcement,traditional foundation grouting reinforcement,and the new co.bined reinforcement schemes were *** numerical simulation performance was verified using a set of field instrumentation data,which demonstrated that the old building response to the overlapped tunnels was under co.trol,and the maximum deformation,angular distortion,and principal tensile strain of the building were 5.25 mm,5.1010–6 rad/m,and 0.0081%,*** with the traditional reinforcement scheme,the deformation,angular distortion,and principal tensile strain in the co.bined reinforcement scheme were reduced by 54.78%,71.02%,and 70.22%,*** results have important implications for the design and construction of shield tunnels and their response to old buildings.

关键词： Overlapped tunnels Reinforcement schemes Under-crossing Old building Numerical simulation

Numerical and theoretical analysis on soil arching effect of prefabricated piles as deep foundation pit supports

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Underground Space 2024年第3期16卷 314-330页

作者： Qianwei Xu Jinli Xie Linhai Lu Yongji Wang Chaojun Wu Qiang Meng Key Laboratory of Road and Traffic Engineering Ministry of EducationTongji UniversityShanghai 201804China Jinan Rail Transit group co. LtdJinan 250101China Guangxi Nanning Airport co.prehensive Transportation Hub construction co. Ltd.Nanning 530048China

This study presents a detailed investigation into the soil arching effects within deep foundation pits(DFPs),focusing on their mechanical behavior and implications for structural *** rigorous 3D finite element modeling and parameter sensitivity analyses,the research explores the formation,geometric characteristics,and spatial distribution of soil arching *** investigation enco.passes the influence of key parameters such as elastic modulus,co.esion,and internal friction angle on the soil arching *** findings reveal that soil arching within DFPs exhibits distinct spatial characteristics,with the prominent arch axis shifting as excavation depth *** soil arching is observed when the pile spacing approximates three times the pile diameter,enhancing soil retention and minimizing deformation *** analyses highlight the significant impact of soil parameters on soil arching behavior,undersco.ing the critical role of co.esive forces and internal friction angles in shaping arching *** elucidating the interplay between soil parameters and soil arching effects,the research provides insights for optimizing pile spacing and structural stability.

关键词： Soil arching effect Numerical analysis Foundation pit support Pile spacing

Enhanced wear prediction of tunnel boring machine disc cutters for accurate remaining useful life estimation using a hybrid model

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Frontiers of Structural and Civil Engineering 2024年第4期18卷 642-662页

作者： Xinghai ZHOU Yakun ZHANG Guofang GONG Huayong YANG Qiaosong CHEN Yuxi CHEN Zhixue SU The State Key Laboratory of Fluid Power&Mechatronic Systems Zhejiang UniversityHangzhou 310027China Guangzhou Rail Transit construction Engineering co.sulting co. Ltd.Guangzhou 510000China China Railway Engineering Equipment group co. Ltd.Zhengzhou 450016China

In tunnel construction with tunnel boring machines(TBMs),accurate prediction of the remaining useful life(RUL)of disc cutters is critical for timely maintenance and replacement to avoid delays and co.t *** paper introduces a novel hybrid model,integrating fundamental and data-driven approaches,to enhance wear prediction of TBM disc cutters and enable accurate RUL *** fundamental model is improved by inco.porating co.posite wear mechanisms and load estimation techniques,showcasing superior prediction accuracy co.pared to single-mechanism ***,the hybrid model innovatively inco.porates a data-driven supplementary residual term into the improved fundamental model,leading to a high-performance wear prediction *** actual field data from a highway tunnel project in Shenzhen,the performance of the hybrid model is rigorously tested and co.pared with pure fundamental and data-driven *** hybrid model outperforms the other models,achieving the highest accuracy in predicting TBM disc cutter wear(mean absolute error(MAE)=0.53,root mean square error(RMSE)=0.64).Furthermore,this study thoroughly analyzes the hybrid model’s generalization capability,revealing significant impacts of geological co.ditions on prediction *** model’s generalization capability is also improved by expanding and updating the data *** RUL estimation results provided by the hybrid model are straightforward and effective,making it a valuable tool by which construction staff can monitor TBM disc cutters.

关键词： tunnel boring machine disc cutter wear prediction remaining useful life field data hybrid model

Research on the design method for uniform wear of shield cutters in sand-pebble strata

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Deep Underground Science and Engineering 2024年第2期3卷 216-230页

作者： Jinxun Zhang Bo Li Guihe Wang Yusheng Jiang Hua Jiang Minglun Yin Zhengyang Sun Beijing Urban construction group co. Ltd.BeijingChina China University of Geosciences BeijingChina China University of Mining and Technology BeijingChina

During shield tunneling in highly abrasive formations such as sand–pebble strata,nonuniform wear of shield cutters is inevitable due to the different cutting *** downtimes and cutter replacements have beco.e major obstacles to long-distance shield driving in sand–pebble *** on the cutter wear characteristics in sand–pebble strata in Beijing,a design methodology for the cutterhead and cutters was established in this study to achieve uniform wear of all cutters by the principle of frictional *** applicability of the design method was verified through three-dimensional simulations using the engineering discrete element *** results show that uniform wear of all cutters on the cutterhead co.ld be achieved by installing different numbers of cutters on each trajectory radius and designing a curved spoke with a certain arch height acco.ding to the shield *** the uniform wear scheme,the cutter wear co.fficient is greatly reduced,and the largest shield driving distance is increased by approximately 47%over the engineering *** research results indicate that the problem of nonuniform cutter wear in shield excavation co.ld be overco.e,thereby providing guiding significance for theoretical innovation and construction of long-distance shield excavation in highly abrasive strata.

关键词： cutter wear EDEM model long-distance shield driving sand-pebble stratum shield tunnel uniform wear design method

Regression Method for Rail Fastener Tightness Based on Center-Line Projection Distance Feature and Neural Network

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 356-371页

作者： Yuanhang Wang Duxin Liu Sheng Guo Yifan Wu Jing Liu Wei Li Hongjie Wang Robotics Research Center School of MechanicalElectronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China China construction Industrial&Energy Engineering group co. Ltd.Nanjing 210023China

In the railway system,fasteners have the functions of damping,maintaining the track distance,and adjusting the track ***,routine maintenance and inspection of fasteners are important to ensure the safe operation of track ***,assessment methods for fastener tightness include manual observation,aco.stic wave detection,and image *** are limitations such as low accuracy and efficiency,easy interference and misjudgment,and a lack of accurate,stable,and fast detection *** at the small deformation characteristics and large elastic change of fasteners from full loosening to full tightening,this study proposes high-precision surface-structured light technology for fastener detection and fastener deformation feature extraction based on the center-line projection distance and a fastener tightness regression method based on neural ***,the method uses a 3D camera to obtain a fastener point cloud and then segments the elastic rod area based on the iterative closest point algorithm *** co.ponent analysis is used to calculate the normal vector of the segmented elastic rod surface and extract the point on the centerline of the elastic *** point is projected onto the upper surface of the bolt to calculate the projection ***,the mapping relationship between the projection distance sequence and fastener tightness is established,and the influence of each parameter on the fastener tightness prediction is ***,by setting up a fastener detection scene in the track experimental base,co.lecting data,and co.pleting the algorithm verification,the results showed that the deviation between the fastener tightness regression value obtained after the algorithm processing and the actual measured value RMSE was 0.2196 mm,which significantly improved the effect co.pared with other tightness detection methods,and realized an effective fastener tightness regression.

关键词： Railway system Fasteners Tightness inspection Neural network regression 3D point cloud processing

Review on frost resistance and anti-clogging of pervious co.crete

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第3期11卷 481-496页

作者： Zhuo Wang Zhichen Liu Feng Zeng Kun He Shuaicheng Guo China Railway construction group co. Ltd.Beijing 100040China State Key Laboratory of Bridge Safety and Resilience College of Civil EngineeringHunan UniversityChangsha 410082China

Pervious co.crete is a special type of co.crete that is of high porosity and co.tains no or a small amount of fine aggregate,and it is an important basic material for sponge city *** presence of a large number of co.nected pores inside pervious co.crete leads to a marked difference in durability failure mechanism co.pared with that of ordinary *** this study,the frost resistance and anti-clogging of pervious co.crete were introduced in detail,and the methods to improve their performance were summarized *** cracking pattern of pervious co.crete is influenced by geometric characteristics and three-dimensional morphological features of pores,resulting in its crack generation,development,and geometry being significantly different from those of ordinary co.crete,thus leading to different freeze-thaw cycle *** addition,due to its different pore structure co.pared to ordinary co.crete,three types of clogging mechanisms,affecting the long-term permeability of pervious co.crete were elaborated systematically(i.e.,physical clogging,biological clogging,and chemical clogging).And the ways to improve the anti-clogging of pervious co.crete are systematically presented from multiple ***,in order to broaden the engineering applications of pervious co.crete,some research proposals are presented in this study.

关键词： Pervious co.crete co.nected pore Frost resistance Clogging mechanism