scholarly journals Simulation on following Performance of High-Speed Railway In Situ Testing System

2013 ◽  
Vol 5 ◽  
pp. 679603
Author(s):  
Fei-Long Zheng ◽  
Liang-Cai Zeng ◽  
Xin-Yuan Chen
Keyword(s):  
High Speed ◽  
Testing System ◽  
In Situ Testing ◽  
High Speed Railway

In-situ investigation on mud pumping in ballastless high-speed railway and development of remediation method

2022 ◽  
pp. 100713
Author(s):  
Zhangbo Wan ◽  
Weichang Xu ◽  
Zhiyuan Zhang ◽  
Chuang Zhao ◽  
Xuecheng Bian
Keyword(s):  
High Speed ◽  
High Speed Railway ◽  
In Situ Investigation ◽  
Mud Pumping

scholarly journals Improvement and In-Situ Application of an Evaluation Method of Ballasted-Track Condition Using Digital 2-D Image Analysis

2020 ◽  
Vol 10 (21) ◽  
pp. 7946
Author(s):  
Bongsik Park ◽  
Yeong-Tae Choi ◽  
Hyunmin Kim
Keyword(s):  
Image Analysis ◽  
High Speed ◽  
Evaluation Method ◽  
Recognition Rate ◽  
High Speed Railway ◽  
Analysis Methods ◽  
Track Condition ◽  
Ballasted Track ◽  
Track Irregularity

The advancement in digital image analysis methods has led to the development of various techniques, i.e., quantification of ballast gravel abrasion. In this study, the recognition rate of gravel aggregates has been significantly increased by improving the image analysis methods. The correlation between the track quality index (TQI), which is the standard deviation of vertical track irregularity and represents the condition of a high-speed railway, and the number of maintenance works was analyzed by performing an image analysis on the samples collected from various locations of a high-speed railway. The results revealed that roundness has the highest correlation with the TQI, whereas sphericity has the highest correlation with the number of maintenance works. The ballast replacement would be performed to improve maintenance efficiency if the abrasion of the ballast aggregates becomes approximately 10%.

Instability Mechanism of Surrounding Rock for Super-Large Cross Section at High-Speed Railway Tunnel Portal

2013 ◽  
Vol 353-356 ◽  
pp. 1597-1603
Author(s):  
Shuang Lan Wu ◽  
Shi Hao Yang ◽  
Xue Wen Zhang
Keyword(s):  
High Speed ◽  
Surrounding Rock ◽  
Instability Mechanism ◽  
Large Cross Section ◽  
Railway Tunnel ◽  
High Speed Railway ◽  
Construction Procedure ◽  
In Situ Conditions ◽  
Major Factors

Difficulties of tunnel construction mainly appear in the entrance and exit stage, some adverse geological problems may occur. In terms of the tunnel at the Changsha-Kunming section of the Shanghai-Kunming passenger line, firstly, adverse geological phenomena at tunnel exits was described. Secondly, major factors leading to disasters were listed, including geology, hydrology and construction procedure. Combined with in-situ conditions, Finite Element Method (FEM) was used to analyze the instability mechanism of surrounding rock after the upper arch gate was excavated by three-bench seven-step exaction method. At last, through comparison between computed result and measuring data, several basic conclusions was obtained. It can make much sense to similar engineering.

Studies on Surface Preparation Systems for Polyurea Protective Coating of Beijing-Shanghai High Speed Railway Bridge Concrete Beams

2012 ◽  
Vol 455-456 ◽  
pp. 765-774
Author(s):  
Wei Bo Huang ◽  
Xu Dong Liu ◽  
Zhang Jing ◽  
Ping Lu
Keyword(s):  
High Speed ◽  
Concrete Beams ◽  
Surface Preparation ◽  
Concrete Surface ◽  
Free Time ◽  
Railway Bridge ◽  
Surface Adhesion ◽  
High Speed Railway ◽  
Comprehensive Performance

. The comprehensive performance of three kinds of surface preparation systems of polyurea coatings for Beijing-Shanghai High-Speed Railway bridge concrete beams’ protection both in situ and in lab were studied in this paper. The pull-off test and visual inspection were used to determine the adhesion and coverage effect of the bug hole of shot blasted concrete surface. Adhesion tests were conducted both in situ and in lab over a period of 1 year. Five failure models were identified based on the failure mechanisms observed during the tests. It showed that, the adhesion strength of Qtech-112 system increased initially (from 2.7 to 4.8 MPa) and then tended to be stable (about 4.5MPa) both in lab and in situ, E1 and E2 system increased initially (from 1.2 to 1.9 MPa) then decreased to 1.3 MPa under low temperature. The tack free time of Qtech-112 was about 3 hours less than E1 and E2 system. Accordingly, the adhesion and tack-free time of epoxy based system (E1, E2) was very sensitive to application temperature and humidity in jobsite. Polyurethane based system (Qtech-112) have a good adhesion and surface coverage effect to concrete surfaces than epoxy based system under the same ambient condition, it showed an excellent comprehensive performance than epoxy one (E1, E2) both in adhesion and in elimination of pinhole for upcoming polyurea application.

Mud pumping in the roadbed of ballastless high-speed railway

Géotechnique ◽  
2021 ◽  
pp. 1-49
Author(s):  
Xuecheng Bian ◽  
Zhangbo Wan ◽  
Chuang Zhao ◽  
Yujun Cui ◽  
Yunmin Chen
Keyword(s):  
High Speed ◽  
Laboratory Tests ◽  
Fine Particles ◽  
Water Source ◽  
Vicious Cycle ◽  
High Speed Train ◽  
High Speed Railway ◽  
Mud Pumping ◽  
Favorable Conditions

Mud pumping intendedly avoided in the design of a ballastless high-speed railway still occurred and induced extraordinary track vibrations. In this study, in situ investigations and laboratory tests were performed to disclose the initiation and development of mud pumping detected in the field. The in situ investigations indicated that mud pumping principally appeared at both ends of the concrete base up to a maximum distance of 2 m. Precipitation, instead of groundwater, was found to be the water source triggering mud pumping, which infiltrated into the graded gravel roadbed through the detachments of the ends of the overlying concrete bases due to the whipping effect. Once mud pumping occurred, the vibrations of concrete bases were aggravated and caused severe track settlements under train loads. The results of laboratory tests indicated that the infiltrated rainwater was retained in the roadbed above the less permeable subgrade, and the roadbed contained an unstable particle skeleton with excessive plastic fine particles, both of which provided favorable conditions to form mud pumping under dense high-speed train loads. Soil particles less than 7.1 mm in diameter migrated during mud pumping, which first accumulated at the lower roadbed, then gradually migrated to the upper roadbed actuated by generated hydraulic gradient, and finally pumped out through the detachments around the expansion gaps, thereby resulting in large amounts of voids in the roadbed and a vicious cycle if not timely treated. These features of mud pumping in ballastless tracks differ from those of ballasted tracks and will benefit the development of remediation measures and improvement of slab track designs.

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