Design Concept and Innovation of Jakarta-Bandung HSR

This paper analyzes the geographical,climatic,cultural and religious factors that influence station building design,and discusses the characteristics and design concepts of traditional Indonesian building.Additionally,the following innovative concepts are proposed for station building design:innovation in the building form that organically integrates high speed railway characteristics with regional features;innovation in spatial layout that adapts to the local climate and culture;innovation in flexible flow lines and diverse commercial spaces;innovation in interior design that fully incorporates the local culture.The station buildings of Jakarta-Bandung HSR not only fulfill the function of passenger riding but also serve as prominent landmark structures that spread regional culture and represent the city's image so as to offer valuable insights for the design of high speed railway station buildings in future overseas projects.

Deformation Mechanism and Design Countermeasures of Tunnel Portal in Volcanic Deposit Clay Stratum

Shortly after tunneling,problems such as primary-support through cracks and clearance infringement are found in the shallow-buried section of tunnel No.4 of the Jakarta-Bandung High Speed Railway(Jakarta-Bandung HSR),and orthogonal cracks can be found on the earth surface in front of the working face,which brings great challenges to the tunnel construction.In view of the above engineering problems,the sliding surface is speculated according to the geological and field conditions,and the impact of landslides is applied in the model in the form of external load.The paper uses the numerical simulation method to analyze and compare the impact of landslides on the tunnel structure and deformation,and puts forward the reinforcement measures.The conclusions of the studies are:(1)under the influence of heavy rainfall,the strength index of volcanic deposit clay stratum drops sharply,and meanwhile the multiple factors including tunnel excavation are liable to cause sliding of the front slope;(2)parallel landslide in front of the tunnel has a great impact on the tunnel,so setting-up of pre-reinforcement measures to control landslide shall be the focus of similar projects during design;(3)the deformation and stress of the tunnel structure can be significantly controlled for safe construction by strengthening the shallow-buried tunnel with pile foundation and longitudinal and transverse beam frames during landslide.

Comparison of microwave- and thermal-assisted rock fragmentation methods at different temperatures and loading rates

Understanding the effects of microwave irradiation and thermal treatment on the dynamic compression and fragmentation properties of rocks is essential to quantify energy consumption in rock engineering.In this study,Fangshan granite(FG)specimens were exposed to microwave irradiation and heat treatment.The damage of FG specimens induced by these two methods was compared using X-ray CT scanning and ultrasonic wave method.The temperatures of FG after microwave irradiation and thermal treatment were effectively evaluated using a newly proposed technique.A novelty method for precisely determining the geometric features of fragments is developed to estimate the fragmentation energy.Thus,the dynamic uniaxial compressive strength(UCS),the dynamic fragmentation characteristics,and the fragmentation energy of FG after these two pretreatment methods can be reasonably compared.The noticeable distinction of loading rate effect on the dynamic UCS of FG between these two pretreatment methods is first observed.A relationship is established between the dynamic UCS and the damage induced by microwave irradiation and heat treatment.Moreover,fragmentation energy fan analysis is introduced to accurately compare the fragmentation properties of FG after two pretreatment methods in dynamic compression tests.

The Influence of Limestone Powder and Metakaolin Co-Blending on the Hydration Process and Mechanical Properties of Q-Phase Cement

A ternary system comprising Ca_(20)Al_(26)Mg_(3)Si_(3)O_(68)(Q-phase),limestone,and metakaolin is proposed,and its hydration behavior,hydration product phases,microstructure,and mechanical properties are investigated and compared with pure Q-phase cement.The results indicate that the ternary system exhibits exceptional and sustained compressive strength even under a 40℃environment,significantly outperforming pure Q-phase.The mechanism lies in that metakaolin effectively inhibits the transformation of metastable phase.Meanwhile,the interactions among Q-phase,limestone,and metakaolin further enhance the cementitious performance.The ternary system effectively addresses potential issues of strength loss in Q-phase cement application,and as a low-carbon cementitious material system,it holds promising potential applications.

A synthetic differencein-differences model for the influence of CR Express on Chongqing's economy

Purpose-The China-Europe Railway Express(CR Express)in Chongqing has operated regularly and undergone large-scale development.Its impact on Chongqing's economic growth has become increasingly evident,necessitating further research in this field.Design/methodology/approach-This study employs the opening of CR Express as a quasi-natural experiment,designating Chongqing,which inaugurated the CR Express in 2011,as the treatment group.13 provinces and cities that had not yet opened the CR Express until 2017 were selected as the control group.Utilizing panel data from 14 provinces across China spanning from 2006 to 2017,the synthetic control method(SCM)is employed to synthetically construct Chongqing.To quantify the difference in economic development levels between Chongqing with the operation of the CR express and Chongqing without its operation.Key metrics such as gross domestic product(GDP),per capita GDP,total retail sales of consumer goods,import and export value and the proportions of the secondary and tertiary industries are employed to measure urban economic development capabilities.Chongqing is designated as the experimental group,and a double-difference model is constructed to regress the operation of the CR Express against economic development capabilities.Robustness tests are conducted to validate the analytical results.Findings-The results indicate that,compared to provinces without the operation of the CR Express,the initiation of the CR Express in Chongqing significantly enhances the economic development level of the city.The opening of the CR Express exhibits a pronounced positive impact on Chongqing's economic development,and these findings remain robust and effective even after parallel trend tests and placebo tests.Originalitylvalue-The study represents an expansion of the theoretical framework.In contrast to previous studies that relied on a single indicator such as GDP,this study selects six indicators from the dimensions of economy,trade and industry to measure regional economic development capabilities.Furthermore,employing the grey relational analysis method,the study screens these indicators,thereby providing a theoretical basis for the selection of indicators for measuring regional economic development capabilities.

Influence of span-to-depth ratio on dynamic response of vehicle-turnoutbridge system in high-speed railway

For high-speed railways,the smoothness of the railway line significantly affects the operational speed of trains.When the train passes through the turnout on a long-span bridge,the wheel-rail impacts caused by the turnout structure irregularities,and the instability arising from the bridge's flexural deformation lead to a strong coupling effect in the vehicle-turnout-bridge system.This significantly affects both ride comfort and operational safety.For addressing this issue,the present study considered a long-span continuous rigid-frame bridge as an example and established a train-turnout-bridge coupled dynamic model of high-speed railway.Utilizing a selfdeveloped dynamic simulation program,the study analysed the dynamic response characteristics when the train passes through the turnouts on the bridge.It also investigated the influence of different span-to-depth ratios of the bridge on the vehicle dynamic response when the train passes through the main line and branch line of turnouts and then proposed a span-to-depth ratio limit value for a long-span continuous rigid-frame bridge.The research findings suggest that the changes in the span-to-depth ratio have a relatively minor impact on the train’s operational performance but significantly affect the dynamic characteristics of the bridge structure.Based on the findings and a comprehensive assessment of safety indicators,it is advisable to establish a span-to-depth ratio limit of 1/4500 for a long-span continuous rigid-frame bridge.

Features of Tropical Volcanic Rock and Soil of Jakarta-Bandung HSR and Engineering Countermeasures

The geological features of three types of tropical volcanic rock and soil distributed along Jakarta-Bandung high-speed railway(HSR),including pozzolanic clayey soil,mud shale and deep soft soil,are studied through field and laboratory tests.The paper analyzes the mechanism and causes of engineering geological problems caused by tropical volcanic rock and soil and puts forward measures to control subgrade slope instability by rationally determining project type,making side slope stability control and strengthening waterproofing and drainage.The“zero front slope”tunneling technology at the portal,the simplified excavation method of double-side wall heading and the cross brace construction method of arch protection within the semi-open cut row pile frame in the“mountainside”eccentrically loaded soft soil stratum are adopted to control the instability of tunnel side and front slopes,foundation pits and working faces;CFG or pipe piles shall be used to reinforce soft and expansive foundation or replacement measures shall be taken,and the scheme of blind ditch+double-layer water sealing in ballastless track section shall be put forward to prevent arching deformation of foundation;the treatment measures of CFG pile,pipe pile and vacuum combined piled preloading are adopted to improve the bearing capacity of foundation in deep soft soil section and solve the problems of settlement control and uneven settlement.These engineering countermeasures have been applied during the construction of Jakarta-Bandung HSR and achieved good results.

The GSM-R Implementation Plan of Jakarta-Bandung High-speed Railway

GSM-R system mainly provides dispatching communication servicessuch as train operation dispatching, realizes wired and wireless dispatchingcommunication, and provides safe and reliable train-ground informationtransmission services for high-speed train operation control system. Jakarta-Bandung HSR is the first “going global” HSR with whole industry chain built by China. It isconstructed based on CTCS-3 train control system standard. In order to ensure the safetransmission of train control system information under high-speed operation environment, aset of GSM-R system implementation scheme suitable for Jakarta-Bandung HSR is establishedin combination with the actual situation of Jakarta-Bandung HSR, referring to China's GSMRsystem technical standards and according to its actual business requirements. It includesGSM-R core network, wireless subsystem and data number, which can provide reference forthe construction of wireless communication system for China's HSR “going global”.

Length optimization of straight line connecting turnout on main line in high-speed railway station yard

Taking the development of high-speed railway in China as background, and referring to the dynamic theory and wheel-rail contact mode, dynamic analysis model was established, considering the setting position of straight lines and running conditions of train in high-speed railway station yard. Using the established model, and choosing vehicle lateral acceleration and wheel suspension as the evaluation indexes, dynamic characteristic of vehicle traveling in turnout and adjacent area on main line was analyzed, and effects on travelling safety and stability of train aroused by length variation of straight lines were calculated based on analyzing the damping rules of vibration. The results show that, a certain length of straight lines can alleviate the vibration aroused in turnout and curve(turnout), length of straight lines connecting turnouts in different sections on main line was proposed to meet the demand of traveling stability, and shortening or cancelation of straight line for the scale limitation of station yard has less influence on operation safety of train.

Anisotropic creep behavior of soft-hard interbedded rock masses based on 3D printing and digital imaging correlation technology

Three-dimensional(3D)printing technology is increasingly used in experimental research of geotechnical engineering.Compared to other materials,3D layer-by-layer printing specimens are extremely similar to the inherent properties of natural layered rock masses.In this paper,soft-hard interbedded rock masses with different dip angles were prepared based on 3D printing(3DP)sand core technology.Uniaxial compression creep tests were conducted to investigate its anisotropic creep behavior based on digital imaging correlation(DIC)technology.The results show that the anisotropic creep behavior of the 3DP soft-hard interbedded rock mass is mainly affected by the dip angles of the weak interlayer when the stress is at low levels.As the stress level increases,the effect of creep stress on its creep anisotropy increases significantly,and the dip angle is no longer the main factor.The minimum value of the long-term strength and creep failure strength always appears in the weak interlayer within 30°–60°,which explains why the failure of the layered rock mass is controlled by the weak interlayer and generally emerges at 45°.The tests results are verified by comparing with theoretical and other published studies.The feasibility of the 3DP soft-hard interbedded rock mass provides broad prospects and application values for 3DP technology in future experimental research.

Pumpability of Manufactured Sand Self-compacting Concrete

By the addition of superplasticizer and air entraining agent,manufactured sand selfcompacting concrete(MS SCC)with slump flow varying from 500 to 700 mm and air content varying from 2.0%to 9.0%were prepared and the pumpability of MS SCC was studied by a sliding pipe rheometer(Sliper).According to the Kaplan’s model,the initial pump pressure and the pump resistance of MS SCC were obtained.Meanwhile,rheological properties including the yield stress and the plastic viscosity of MS SCC were measured by a rheometer.The experimental results show that the increase of slump flow contributes to a higher pumpability and a proper air content,i e,6%is beneficial for the pumpability of MS SCC.Due to the existence of stone powder and stronger angularity of MS,the initial pump pressure of MS SCC is only about 60%-88%that of river sand(RS)SCC with the same slump flow and air content,indicating that MS SCC possesses a higher pumpability than RS SCC.

Key Technologies for Design of Changqing Yellow River Super-long Bridge of Zhengzhou Ji'nan HSR

Changqing Yellow River Super-long Bridge of Zhengzhou-Ji'nan HSR is a partial cable-stayed bridge with concrete main girder and a unit length of 1,080 m.Studies are carried out on the key technologies of bridge design,and the main conclusions are as follows:The whole unit adopts the supporting system of tower pier consolidation and tower-beam separation,and each pier is provided with seismic mitigation and isolation bearing;shaped-steel reinforced concrete bridge tower is adopted to bring into full play the tensile performance of steel and the compressive performance of concrete,and avoid the construction challenges of setting up multi-layer and multi-stirrup reinforcement while improving the bearing capacity of section;a new type of double-side and bi-directional anti-skid anchorage device is adopted for the cable saddle of wire divider pipe in order to withstand the unbalanced cable force,and verify the reliability of the anti-skid anchorage device by solid model test;and large-segment cantilever pouring design is adopted for the main girder with a maximum segment length of 8 m to effectively shorten the construction period of the bridge.

Key Technology and Complete-set Equipment for Intelligent Construction of HSR Simply-supported Girder Reinforcement Framework

In view of the problems such as backward production mode,poor quality stability,high safety risk and incomplete control system during erection of the reinforcement framework of simply-supported box girders for high-speed railway(HSR),and in combination with the key points and main challenges in the reinforcement framework construction of Guangzhou-Zhanjiang HSR,the overall technical route for the intelligent manufacturing of reinforcement framework of simply-supported box girders is put forward.The component design of reinforcement framework of simply supported box girder is carried out based on BIM,and the feasibility of the scheme is verified through segment assembly test.The assembly techniques are studied in combination with the mesh design scheme to achieve rapid forming of the reinforcement framework.R&D of automatic processing equipment for components,material transshipment equipment,automatic hoisting equipment and technological equipment for assembly clamping fixture are carried out to realize the overall design of equipment production line.An intelligent control system is developed for the whole-process intelligent construction of reinforcement framework to realize the full life-cycle applications for the workshop production and visual management including intelligent layout and quality traceability.The research results systematically optimize and innovate the assembly and forming technologies of reinforcement framework in the prefabrication beam yard of high-speed railway,realize the component processing,automatic assembly and information technology management,improve the construction quality,efficiency and information technology level of intelligent manufacturing of reinforcement framework of railway prefabricated beam as a whole,and reduce the construction cost of the project.The research has realized a major breakthrough in the construction technology of railway prefabricated box girders,which has the extensive technical and market promotion values.

A method for support stiffness failure identification in a steel spring floating slab track of urban railway: a case study in China

The extensive use of steel spring floating slab tracks has effectively addressed the challenge of alleviating the environmental vibrations induced by urban rail transit systems.However,under the combined action of train dynamic loads and complex environmental factors,problems,such as the fracture of steel spring vibration isolators and suspension vibrations induced by the uneven settlement of the base,often occur.The failure of isolator support stiffness is often hidden in its early stages and is challenging to identify by conventional detection methods.At the same time,it will aggravate the wheel-rail interaction,accelerate the deterioration of track structure,and even affect the driving safety.This study first establishes a detailed coupled train-floating slab track-foundation analytical model.Then the influence of the vibration isolator support stiffness failure on the dynamic indices of the floating slab track system response is analyzed.A set of defect identification methods that can detect the number of failed steel springs,severity of damage,and their location is proposed.Finally,an intelligent monitoring system for support stiffness of floating slab track is built by combining the density-based spatial clustering of applications with noise algorithm and statistical data analysis and is applied to a rail line in southern China.During a three-year monitoring campaign,a suspension failure and a fracture of a steel spring were each successfully detected and detailed failure information was obtained.Field investigation results were consistent with the damage identification results.After repair,the track structure dynamic response returned to the average pre-damage level and further deterioration had been arrested.The proposed damage identification methods and monitoring system provide an approach for intelligent identification of track structure support stiffness failures.

Localized Application of Chinese Standards in Jakarta-Bandung HSR Project

Jakarta-Bandung HSR in Indonesia is the first“go global”project of China's high speed railway with a whole system,all elements and a whole industry chain,as well as the first overseas project adopting a complete set of Chinese standards.This paper sorts out the differences between relevant standards in China and Indonesia,including those in concrete raw materials,rebar standards and other main material standards,and those in external interface standards,train operation direction requirements,project approval requirements,special acceptance requirements,etc.,and summarizes the realization methods and specific achievements of localized application of Chinese standards during the implementation of Jakarta-Bandung HSR Project,to provide reference for localized application of Chinese standards in overseas projects in the future.

Deformation characteristics and safety assessment of a high-speed railway induced by undercutting metro tunnel excavation

Stratum deformation(settlement) is a challenging issue in tunnel engineering, especially when construction of metro tunnels has to undercut high-speed railway. For this purpose, we used the FLAC30 software to analyze the stratum settlement characteristics of high-speed railway at different crossing angles intersected by metro tunnel, in terms of ground settlement trough, stratum slip line and irregularity of ballastless tracks. According to the evolution of the stratum settlement at different angle regions, an optimized angle is proposed for the actual project design. In order to reduce the influence of stratum settlement on the safety of high-speed railway, an approach of safety assessment is proposed for the shield engineering undercutting high-speed railway, as per Chinese specifications using numerical results and on-site conditions. A case study is conducted for the shield tunnel section crossing the Wuhan-Guangzhou High-speed Railway between the Guangzhou North Railway Station and the Huacheng Road Station, which represents the first metro tunnel project passing below a high-speed railway in China. A series of measures is taken to ensure the safe excavation of the shield tunnel and the operation of the high-speed railway. The results can provide a technical support for performing a safety evaluation between high-speed railways and metro tunnels.

Aerodynamic coefficient of vehicle-bridge system by wind tunnel test

The changes of three components of aerodynamic force were discussed with the attack angle conversion for three kinds of section models. Based on the project of Shanghai Yangtze River Bridge, the wind tunnel test was conducted to obtain its three components of aerodynamic force including 75 conditions of the construction stage, the bridge without vehicles and the bridge with vehicles from - 12 degrees to ＋ 12 degrees. For the bridge with vehicles, the drag force coefficient and the absolute value of both lift coefficient and moment coefficient were decreased by the vehicles. The test resuh shows that the bridge railing and vehicles have much influence on the three components of aerodynamic force of the vehicle-bridge system for Shanghai Yangtze River Bridge.

Probabilistic limit state design methodof the axial resistance of post grouting pile

The reliability of post grouting pile axial resistance was studied by proposing a design method for its probabilistic limit state,which is represented by the partial coefficients of load,end,and side resistance.The hyperbolic,modified hyperbolic,and polynomial models were employed to predict the ultimate bearing capacity of test piles that were not loaded to damage in field tests.The results were used for the calculation and calibration of the reliability index.The reliability of the probabilistic limit state design method was verified by an engineering case.The results show that the prediction results obtained from the modified hyperbolic model are closest to those obtained through the static load test.The proposed corresponding values of total,side,and end resistance partial coefficients are 1.84,1.66,and 2.73 when the dead and live load partial coefficients are taken as 1.1 and 1.4,respectively.Meanwhile,the corresponding partial coefficients of total,side,and end resistance are 1.70,1.56,and 2.34 when the dead and live load partial coefficients are taken as 1.2 and 1.4,respectively.

Cyclic test and numerical study of seismic performance of precast segmental concrete double-columns

The comparative research on the seismic performance of grouted sleeve connected pier(GS)and prestressed precast segmental concrete pier(PC)is mostly carried out by numerical simulation.In this study,the GS pier and the PC pier of the new railway project from Hetian to Ruoqiang are taken into consideration.Two kinds of 1/5-scale assembled double-column specimens are made,and the quasi-static tests are carried out.The overall seismic performance of the two spliced piers is studied,and compared in terms of failure mechanism,bearing capacity,ductility,stiffness and energy dissipation capacity.The results show that the failure modes of both GS pier and PC pier are characterized by bending.However,the specific failure location and form are different.The GS pier presents a complete hysteretic curve,large equivalent stiffness and strong energy dissipation capacity.The hysteretic area of the PC pier is small.However,it has good self-reset ability and quasi-static residual displacement.Finite element models are set up using DispBeamColumn fiber elements and ZeroLength elements.The models that are calibrated with the test data can effectively simulate the damage development under monotonic loading.The load−displacement curves are in good agreement with the backbone curves of the test results.

Pavement Performance Research Progress and Evaluation of Asphalt Mixture Incorporating Iron Ore Tailings

In order to solve the problems caused by the storage of iron ore tailings (IOTs), many researchers conducted a series of experimental studies on the reuse of IOTs. The results of many studies showed that it was feasible to use IOTs for road engineering. This paper summarized the composition, gradation and particle characteristics of IOTs from chemical and physical aspects, and proved the feasibility of IOTs replacing traditional aggregate for asphalt concrete. Then, the research on the road performance of asphalt concrete incorporating IOTs were summarized and reviewed, including the evaluation of high-temperature stability, low-temperature crack resistance, fatigue resistance and water stability. The water stability and the improvement of adhesion between asphalt and IOTs aggregate were discussed in detail. Finally, the performance of IOTs as asphalt concrete aggregate and the existing defects were evaluated, and future research directions were proposed.