Study on Optimized Mix-Proportion and Crack Resistance of Modern Secondary Lining Concrete for High-Speed Railway Tunnel

2010 ◽  
Vol 168-170 ◽  
pp. 106-110 ◽  
Author(s):  
Li Ping Guo ◽  
Wei Sun ◽  
Qing Yu Cao ◽  
Jin Yu Zong
Keyword(s):  
Crack Resistance ◽  
High Speed ◽  
Test Results ◽  
Railway Tunnel ◽  
Curing Conditions ◽  
Air Voids ◽  
Mix Proportion ◽  
Surrounding Rock Pressure ◽  
Secondary Lining ◽  
Fine Organic

Cracking is the most common damage in the secondary lining concrete because of its continuous thin-walled structure, potential surrounding rock pressure and poor curing conditions. In order to improve the crack resistance of concrete and to reduce the responding costs, seven series modern concretes including ultra-fine pozzolanic powder and different organic fibers are prepared and investigated. The optimized modern secondary lining concrete is determined as the concrete including 0.08% or 0.1% volume fractions of ultra-fine organic fiber (UF), based on the test results of segregation, air voids parameters, primary strengths and multi-factorial crack resistance. The spacing factor and average chord length of concretes including UF are less than 0.1mm, which is positive for mixing UF to enhance the crack resistance of concrete at micro- and meso-scale.

Study on Gas Anti-Permeability of Fiber Concrete under Fatigue Loading

2011 ◽  
Vol 243-249 ◽  
pp. 793-796
Author(s):  
Qing Yu Cao ◽  
Wei Sun ◽  
Li Ping Guo
Keyword(s):  
Gas Permeability ◽  
Fatigue Loading ◽  
Surrounding Rock ◽  
Test Results ◽  
Curing Conditions ◽  
Fiber Concrete ◽  
Result Show ◽  
Surrounding Rock Pressure ◽  
Secondary Lining ◽  
Fine Organic

Cracking is the most common damage in the secondary lining concrete because of its continuous thin-walled structure, potential surrounding rock pressure and poor curing conditions. In order to improve the fatigue and gas perimeability resistance of concrete and to reduce the responding costs, four series modern concretes including ultra-fine pozzolanic powder and organic fibers are prepared and investigated. The optimized modern secondary lining concrete is determined as the concrete including 0.08% or 0.1% volume fractions of ultra-fine organic fiber (UF), based on the test results of fatigue life and coefficient of gas-permeability under fatigue loading. The result show fiber concrete is positive for enhancing the fatigue and gas permeability resistance and can apply for the tunnel secondary lining.

scholarly journals Structural Responses of Secondary Lining of High-Speed Railway Tunnel Excavated in Loess Ground

2013 ◽  
Vol 16 (8) ◽  
pp. 1371-1379 ◽  
Author(s):  
Dingli Zhang ◽  
Qian Fang ◽  
Pengfei Li ◽  
Louis Ngai Yuen Wong
Keyword(s):  
High Speed ◽  
Railway Tunnel ◽  
High Speed Railway ◽  
Structural Responses ◽  
Secondary Lining

scholarly journals Temporal and Spatial Effect of Surrounding Rock and Supporting Construction of a Large Soil Tunnel

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Wanjun Ye ◽  
Yuntao Wu ◽  
Ming Chen ◽  
Chong Gao
Keyword(s):  
Contact Pressure ◽  
Rock Pressure ◽  
Release Rate ◽  
Rapid Growth ◽  
High Speed ◽  
Surrounding Rock ◽  
Measuring Point ◽  
Finite Element Software ◽  
Surrounding Rock Pressure ◽  
Secondary Lining

Based on the Zaosheng No. 3 tunnel of the Yinchuan-Xi’an high-speed railway, the surrounding rock pressure, contact pressure of the primary support, and secondary lining and internal force of the secondary lining concrete are systematically tested using a vibrating wire sensor, and the correlation between the advance construction distance and the surrounding rock release rate is studied with finite element software. The results show that the pressure on the surrounding rock is low when the deeply buried soil tunnel is excavated and can be divided into three stages: rapid growth, slow growth, and flattening with time. It is more reasonable to calculate the surrounding rock pressure by using tunnel planning calculations. For the contact pressure, although the value of each measuring point in the inverted arch changes a little, the arch pressure obviously has the characteristics of rapid growth and a sharp rebound. Most of the test points of the second lining concrete show a compression state, which is far less than the ultimate compressive strength. At the same time, the initial support of the tunnel bears a large load, while the secondary lining bears a relatively small force, and the load sharing ratio of the two ranges between 0.1 and 0.7; with the progress of the excavation section, the surrounding rock deformation (deformation release rate) increases gradually. When the excavation face is close to the monitoring section, the deformation (deformation release rate) is the most severe. With the increase in the distance between the excavation section and the monitoring section, the deformation (deformation release rate) tends to be flat.

Mechanical Analysis of Secondary Lining of High-Speed Railway Tunnel

2017 ◽  
Vol 22 (7) ◽  
pp. 2384-2389 ◽  
Author(s):  
Ningning Zhang ◽  
Qian Fang ◽  
Yue Li ◽  
Dingli Zhang
Keyword(s):  
High Speed ◽  
Mechanical Analysis ◽  
Railway Tunnel ◽  
High Speed Railway ◽  
Secondary Lining

Investigation of a loess-mudstone landslide and the induced structural damage in a high-speed railway tunnel

2020 ◽  
Vol 79 (5) ◽  
pp. 2201-2212
Author(s):  
Shunhua Zhou ◽  
Zhiyao Tian ◽  
Honggui Di ◽  
Peijun Guo ◽  
Longlong Fu
Keyword(s):  
Structural Damage ◽  
High Speed ◽  
Railway Tunnel ◽  
High Speed Railway

Measurement and Analysis on Transient Thermal Characteristics of High Speed Motorized Spindle

2011 ◽  
Vol 52-54 ◽  
pp. 2021-2026
Author(s):  
Gui Ling Deng ◽  
Can Zhou
Keyword(s):  
High Speed ◽  
Thermal Deformation ◽  
Thermal Characteristics ◽  
Measuring System ◽  
Test Results ◽  
Motorized Spindle ◽  
Measurement And Analysis ◽  
Turning Center ◽  
Transient Thermal ◽  
Deformation Compensation

Thermal deformation is an important factor to affect the accuracy of the motorized spindle, the core component of high-speed machine tool. To understand the spindle system transient thermal characteristics of the high-speed turning center CH7516GS, some high-precision sensors and high-frequency data acquisition system is used to establish the temperature and displacement measuring system. The thermal deformation compensation model is established on the basis of the experimental test results.

The Calculation of Train Slipstreams on Platform of Underground High-Speed Rail Station

2013 ◽  
Vol 842 ◽  
pp. 445-448
Author(s):  
Wei Chao Yang ◽  
Chuan He ◽  
Li Min Peng
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Horizontal Distribution ◽  
Wake Flow ◽  
Railway Tunnel ◽  
Long Distance ◽  
Near Wake ◽  
High Speed Rail ◽  
Numerical Work ◽  
Rail Station

This paper describes the results of numerical work to determine the flow structures of the slipstream and wake of a high speed train on platforms of underground rail station using three-dimensional compressible Euler equation. The simulations were carried out on a model of a simplified three-coach train and typical cross-section of Chinese high-speed railway tunnel. A number of issues were observed: change process of slipstreams, longitudinal and horizontal distribution characteristics of train wind. Localized velocity peaks were obtained near the nose of the train and in the near wake region. Maximum and minimum velocity values were also noticed near to the nose rear tip. These structures extended for a long distance behind the train in the far wake flow. The slipstream in platform shows the typical three-dimensional characteristics and the velocity is about 4 m/s at 6 m away from the edge of platform.

Some problems of assessing the dynamic crack resistance of structural steels

2021 ◽  
Vol 18 (3) ◽  
pp. 428-435
Author(s):  
Vladimir I. SMIRNOV ◽  
◽  
Tatiana A. KNOPOVA ◽  
Sergey S. MAYER ◽  
◽  
...  
Keyword(s):  
Crack Resistance ◽  
High Speed ◽  
Dynamic Testing ◽  
Practical Importance ◽  
Dynamic Strength ◽  
Structural Steels ◽  
Dynamic Crack ◽  
Unstable Fracture ◽  
Structural Elements ◽  
Limiting State

Objective: Solving the problem of determining the conditions for the onset and development of unstable fracture, which is extremely important for the development of methods for calculating the limiting states of structural elements, improving the dynamic testing schemes of materials and classifying steels according to their ability to resist fracture. Methods: Analytical methods for assessing the limiting state of structural elements are used. Results: A brief overview of the available test methods for structural steels for dynamic strength and crack resistance is given. The experience accumulated by domestic and foreign practices in testing steels for strength and crack resistance under high-speed loading is analyzed. The disadvantages of the existing methods for assessing the indicators of dynamic strength and resistance to brittle fracture are indicated. Practical importance: It is shown that along with the traditional methods for assessing strength based on safety factors, it is necessary to develop and apply new methods for assessing the limiting state of structural elements, including by the criteria of crack resistance

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