scholarly journals Dynamic Response of the Entrance Structure of an Elliptical Mountain Tunnel under the Action of SH Waves

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Zhenyu Wang ◽  
Junsheng Yang ◽  
Xinghua Wang
Keyword(s):  
Analytical Solution ◽  
Mirror Symmetry ◽  
High Speed ◽  
Large Scale ◽  
Strain Curve ◽  
Shaking Table ◽  
Railway Tunnel ◽  
Tangential Strain ◽  
Entrance Section ◽  
Mountain Tunnel

Generally, the surrounding rock at the entrance of a mountain tunnel is loose, and the entrance has more slopes due to topography, which causes the tunnel entrance section to be easily destroyed under an earthquake. Based on the established slope model with a single free surface, this paper adopted the elastic wave theory to derive the analytical solution of the strain at the entrance of the mountain tunnel when the SH wave is incident perpendicularly to the bottom of the tunnel; besides, the factors affecting strain were also analyzed. The tangential strain curve at each point of the entrance section takes the centre of the elliptical tunnel as the centre of symmetry, forming symmetry between the left and right sides and mirror symmetry between the top and bottom sides. Then, large-scale shaking table model experiments were conducted to model the actual working conditions, and the correctness of the analytical solution was verified. The research can provide a theoretical reference for the seismic design of the entrance section of the high-speed railway tunnel and greatly improve the understanding of its seismic response.

scholarly journals DEVELOPMENT OF A HIGH-SPEED VIDEOGRAMMETRIC MEASUREMENT SYSTEM WITH APPLICATION IN LARGE-SCALE SHAKING TABLE TEST

2019 ◽  
Vol IV-2/W7 ◽  
pp. 33-38
Author(s):  
S. Gao ◽  
Z. Ye ◽  
C. Wei ◽  
X. Liu ◽  
X. Tong
Keyword(s):  
Data Processing ◽  
Measurement System ◽  
High Speed ◽  
Large Scale ◽  
Moving Objects ◽  
Shaking Table Test ◽  
Image Sequences ◽  
Shaking Table ◽  
Dynamic Monitoring ◽  
Observation Network

<p><strong>Abstract.</strong> The high-speed videogrammetric measurement system, which provides a convenient way to capture three-dimensional (3D) dynamic response of moving objects, has been widely used in various applications due to its remarkable advantages including non-contact, flexibility and high precision. This paper presents a distributed high-speed videogrammetric measurement system suitable for monitoring of large-scale structures. The overall framework consists of hardware and software two parts, namely observation network construction and data processing. The core component of the observation network is high-speed cameras to provide multiview image sequences. The data processing part automatically obtains the 3D structural deformations of the key points from the captured image sequences. A distributed parallel processing framework is adopted to speed up the image sequence processing. An empirical experiment was conducted to measure the dynamics of a double-tube five-layer building structure on the shaking table using the presented videogrammetric measurement system. Compared with the high-accuracy total station measurement, the presented system can achieve a sub-millimeter level of coordinates discrepancy. The 3D deformation results demonstrate the potential of the non-contact high-speed videogrammetric measurement system in dynamic monitoring of large-scale shake table tests.</p>

scholarly journals Experimental Investigation of Load-Bearing Mechanism of Underwater Mined-Tunnel Lining

2021 ◽  
Vol 9 (6) ◽  
pp. 627
Author(s):  
Zhiqiang Zhang ◽  
Binke Chen ◽  
Qingnan Lan
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Water Pressure ◽  
Tunnel Lining ◽  
Scale Model ◽  
Soil Pressure ◽  
Railway Tunnel ◽  
Load Bearing ◽  
Water Head ◽  
Design Speed

A series of model tests were performed to investigate the load-bearing mechanism of a mined railway tunnel lining under water pressure. To investigate the load-bearing characteristics of different types of linings, a fully closed water pressure exerting device for a noncircular section tunnel was invented. A large-scale model test (1:30) under combined water and soil pressures was conducted to investigate the mechanical characteristics, deformation, stress distribution, crack development process, and failure mode of the underwater mined-tunnel lining. The test results indicated that for the high-speed railway tunnel of Class IV surrounding rock with a design speed of 350 km/h, both the drainage lining and the waterproof lining were controlled by a small eccentric compression under the two test conditions. One had only water pressure, and the other had a variable water pressure and constant soil pressure. The key sections for controlling instability were the bottom of the wall and the inverted arch. The ultimate water head of the drainage lining was 49 m, and the ultimate water head of the waterproof lining was 78 m. In comparison with the drainage lining, the waterproof lining could significantly improve the water-pressure resistance. Thus, design loads of 30 and 60 m are recommended for the drainage and waterproof lining structures, respectively.

scholarly journals Tri-Camera High-Speed Videogrammetry for Three-Dimensional Measurement of Laminated Rubber Bearings Based on the Large-Scale Shaking Table

2018 ◽  
Vol 10 (12) ◽  
pp. 1902 ◽  
Author(s):  
Xiaohua Tong ◽  
Kuifeng Luan ◽  
Xianglei Liu ◽  
Shijie Liu ◽  
Peng Chen ◽  
...  
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Three Dimensional ◽  
Image Sequences ◽  
Bundle Adjustment ◽  
Shaking Table ◽  
Camera Image ◽  
Rubber Bearing ◽  
Laminated Rubber Bearing ◽  
Rubber Bearings

Laminated rubber bearings are widely used for the mitigation of seismic damage of large-scale structures and equipment. However, owing to the flexibility in horizontal direction, the traditional contacted transducer is difficult to acquire the displacement data accurately in the three directions, respectively. In this paper, three-dimensional displacement measurement of laminated rubber bearing based on the large-scale shaking table is achieved by the use of a tri-camera high-speed videogrammetric system consisting of three complementary-metal-oxide-semiconductor (CMOS) cameras, one synchronous controller, and one pair of 1000 watt light sources, which are used to simultaneously acquire the tri-camera image sequences of laminated rubber bearing at a speed of 300 frames per second (fps). Firstly, this paper proposes a fast image block technique for detecting and tracking targets in tri-camera image sequences by integration of techniques morphological edge detection, attribute based ellipse extraction and least-squares-based fitting adjustment. Secondly, this paper presents an integrated bundle adjustment approach, which brings continuous tracking points into one collinearity condition equation, to reconstruct the three dimensional coordinates of continuous tracking points, for the purpose of improving the accuracy of three-dimensional coordinates of tracking points based on tri-camera image sequences. At last, an empirical experiment was conducted to measure the three-dimensional displacement of laminated rubber bearings on the shaking table by the use of the proposed method. The experimental results showed that the proposed method could obtain three-dimensional displacement of laminated rubber bearings with an accuracy of more than 0.5 mm.

Structures and Settlement Control of Yujingshan High-Speed Railway Tunnel Crossing Massive Rockfill in a Giant Karst Cave

2021 ◽  
pp. 036119812110624
Author(s):  
Yipeng Xie ◽  
Junsheng Yang ◽  
Cong Zhang ◽  
Jinyang Fu
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Three Dimensional ◽  
Railway Tunnel ◽  
High Speed Railway ◽  
Settlement Behavior ◽  
Underground River ◽  
Convergence Trend ◽  
Dimensional Coupling

The Yujingshan high-speed railway tunnel crosses a giant cavern system with a 108 × 104 m3 volume chamber and an 18 km long underground river. The massive project, which lasted three years, was eventually awarded the “Overcoming the Challenges” award by the International Tunneling and Underground Space Association (ITA) in 2020. However, since the cave chamber was filled with large-scale rockfill, structural settlement is a non-negligible problem. This paper presents the unique structures of a bridge supporting railway tracks wrapped by tunnel lining and the settlement control of the Yujingshan tunnel crossing massive rockfill in the giant cave. The geological characteristics and design considerations are systematically introduced. A three-dimensional coupling discrete element method (DEM) and finite difference method (FDM) numerical model and 13 months of long-term settlement monitoring were conducted to evaluate the settlement behavior. The results indicate that the morphology of cavern and internal deposits caused the whole rockfill to migrate to the lower left. The tunnel structure consequently developed a significant inclined settlement. The continuous construction load would increase the settlement value by 31.4%. The bottom reinforcement of steel-pipe pile with grouting could effectively inhibit settlement and differential settlement. Considering the simulation results, the tunnel bottom had greater settlement than the limit standard for high-speed railway embankment, which means this special structure form is reasonable for operation. Meanwhile, the monitoring results show that the tunnel bottom settlement in D3K279+891~D3K279+947 had not performed an apparent convergence trend after 13 months. Further structural monitoring and compensation grouting should be actively considered for operation maintenance.

Risk Assessment of High-Speed Railway Tunnel Construction Based on Fuzzy Synthetic Evaluation

2012 ◽  
Vol 594-597 ◽  
pp. 1251-1256
Author(s):  
Li Wu ◽  
Liang Gang Zhang ◽  
Yun Lai ◽  
Jian Chen
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Evaluation Index System ◽  
Tunnel Construction ◽  
Fuzzy Synthetic Evaluation ◽  
Railway Tunnel ◽  
Analytic Hierarchy ◽  
High Speed Railway ◽  
Construction Risk ◽  
Synthetic Evaluation

Because of its large scale, long cycle and complex construction, the high speed railway tunnel construction exists many uncertain risk factors which are random and fuzzy, that makes it difficult to do quantitative analysis by general research methods. A synthetic evaluation index system for tunnel construction risk of high-speed railway is established by analyzing the factors that influence high-speed railway construction, and the analytic hierarchy process is used to determine the weight of each stage factor. Based on the hierarchy of each factor, a model of three-stage fuzzy synthetic evaluation is proposed, the fuzzy sets method is used to determine membership function, and risk ranking is also classified. The proposed method is applied to a Tian jiashan Tunnel construction of Shanghai-Kunming (Hu-Kun) high-speed railway. The analysis results show that the method is reasonable and practical, and it will be taken as an example by other similar projects.

Do elite soccer players cover longer distance when losing? Differences between attackers and defenders

2020 ◽  
pp. 174795412098227
Author(s):  
Carlos Lago-Peñas ◽  
Anton Kalén ◽  
Miguel Lorenzo-Martinez ◽  
Roberto López-Del Campo ◽  
Ricardo Resta ◽  
...  
Keyword(s):  
New York ◽  
High Speed ◽  
Large Scale ◽  
Tracking System ◽  
Soccer Players ◽  
Running Performance ◽  
Situational Variables ◽  
Total Distance ◽  
Professional Soccer ◽  
Score Line

This study aimed to evaluate the effects playing position, match location (home or away), quality of opposition (strong or weak), effective playing time (total time minus stoppages), and score-line on physical match performance in professional soccer players using a large-scale analysis. A total of 10,739 individual match observations of outfield players competing in the Spanish La Liga during the 2018–2019 season were recorded using a computerized tracking system (TRACAB, Chyronhego, New York, USA). The players were classified into five positions (central defenders, players = 94; external defenders, players = 82; central midfielders, players = 101; external midfielders, players = 72; and forwards, players = 67) and the following match running performance categories were considered: total distance covered, low-speed running (LSR) distance (0–14 km · h−1), medium-speed running (MSR) distance (14–21 km · h−1), high-speed running (HSR) distance (>21 km · h−1), very HSR (VHSR) distance (21–24 km · h−1), sprint distance (>24 km · h−1) Overall, match running performance was highly dependent on situational variables, especially the score-line condition (winning, drawing, losing). Moreover, the score-line affected players running performance differently depending on their playing position. Losing status increased the total distance and the distance covered at MSR, HSR, VHSR and Sprint by defenders, while attacking players showed the opposite trend. These findings may help coaches and managers to better understand the effects of situational variables on physical performance in La Liga and could be used to develop a model for predicting the physical activity profile in competition.

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