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.

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.

Customized High-speed EMU Design Practice for Jakarta-Bandung HSR

The high-speed EMUs for Jakarta-Bandung high-speed railway(HSR)represent an important image and symbol of the Jakarta-Bandung HSR Project.By relying on the technical platform of the model CR400 EMU,the EMU is upgraded for the customized design in terms of adaptability to geographical environment and track conditions,integration of Indonesian cultural characteristics,etc.In the course of development,in order to accurately grasp the boundary conditions and solve matching adaptation problems,studies are conducted on the exploration of design boundary and the related special technology.With the systematic analysis and design experience summary of the high-speed EMUs for Jakarta-Bandung HSR,the paper aims to provide reference for the O&M of high-speed EMUs for Jakarta-Bandung HSR and the other similar overseas HSR projects.

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.

Comparison and Selection of Arch-Rib Construction Schemes for Continuous Beam arch Composite Bridge of High Speed Railway

The paper summarizes the four different construction schemes based on engineering cases for the arch rib construction of continuous beam-arch composite bridges for high-speed railways.These methods include in-situ assembly,segmental lifting,incremental launching and longitudinal moving,and vertical rotation.The temporary structural designs,process methods,and technological equipment for each construction scheme are described in detail.The advantages and disadvantages of each scheme and its application scope under various conditions are analyzed,and opinions and suggestions for guiding the application of each scheme are proposed.The comparison and selection analyses show that the four arch rib construction schemes have certain applicability under different conditions such as bridge site status,bridge span,and construction environment.With the continuous increase of bridge span and progress of construction technological equipment,the arch rib construction technology is developing towards the overall erection direction.This leads to more obvious technical advantages of the segmental lifting method,incremental launching and longitudinal moving method,and vertical rotation method.Therefore,it is necessary to select the best construction scheme according to the construction status and technical conditions during application.

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.