scholarly journals Research on Stress Characteristics of Segment Structure during the Construction of the Large-Diameter Shield Tunnel and Cross-Passage

Symmetry ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1246
Author(s):  
Zhongsheng Tan ◽  
Zonglin Li ◽  
Wei Tang ◽  
Xueying Chen ◽  
Junmeng Duan
Keyword(s):  
High Speed ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Large Diameter ◽  
Bending Moment ◽  
Shield Tunnel ◽  
Railway Network ◽  
Maximum Deformation ◽  
Intercity Railway ◽  
The Stability

With the intensive development of China’s high-speed railway network and intercity railway network, the construction of the large-diameter shield tunnels and cross-passages is gradually increasing. The construction of large diameter shield tunnels and the excavation of cross-passages puts forward higher requirements for the stability and safety of segment structure. Based on the Wangjing tunnel project, this paper studies the segment displacement and mechanical response of the shield tunnel with a diameter of 10.5 m in the process of shield construction and cross-passage construction. The results show that during the construction of large diameter shield tunnels, the vault and invert produce inward displacement, the invert uplift usually is more severe than the vault settlement, and the arch waist on both sides produces outward displacement. Near the segment K (capping block), the mechanical performance of the segment is close to that of the hinge or chain rod, which can only effectively transmit the axial force but cannot resist the bending moment and shear force. During construction of the cross-passage, the maximum deformation and stress of shield tunnel segment are symmetrically located at the interface of the main tunnel and cross-passage. The upper and lower edges of the segment at the interface tend to change from compression to tension. At the same time, the steel bars on the inside and outside of the segment vault and the arch waist change from compressive stress to tensile stress, which can easily lead to segment damage, so these positions can be reinforced by erecting section steel frames before construction.

Analysis on Influence of Shield Tunnel Crossing under Intercity High-Speed Railway Station

2011 ◽  
Vol 90-93 ◽  
pp. 1904-1910
Author(s):  
Sheng Rong Lu ◽  
Quan Mei Gong ◽  
Yu Jia
Keyword(s):  
High Speed ◽  
Concrete Slab ◽  
Bending Moment ◽  
Shield Tunnel ◽  
Shield Tunneling ◽  
Railway Station ◽  
High Speed Railway ◽  
Bored Pile ◽  
Intercity Railway ◽  
Bored Piles

Based on an engineering example of a certain shield tunnel passing through an intercity high-speed railway station which has been reinforced by pile-slab structure, this paper adopts finite element numerical simulation to study the influence of shield tunneling construction on the pile-slab reinforced structure and railway subgrade. The research result shows that the horizontal displacement and additional bending moment on both sides of bored piles are increasing in the process of shield tunneling, while those of the middle bored pile firstly increase and then decrease. The vertical displacement and axial force variation of the middle bored pile are more obvious than that on both sides of the bored piles. The settlement and additional bending moment of the reinforced concrete slab are relatively large in the center and midspan of both sides, the position of maximum settlement and negative bending moment is near the concrete slab just above the right tunnel, while the maximum positive bending moment is located in the very middle of the concrete slab. The pile-slab reinforced structure can effectively control the settlement and differential settlement of the intercity railway subgrade caused by shield tunneling, thus the intercity railway can keep normal operation.

Ultra Precision Machining of the Winston Cone Baffle for Space Observation Camera

2012 ◽  
Vol 516 ◽  
pp. 42-47
Author(s):  
Sun Choel Yang ◽  
Geon Hee Kim ◽  
Myung Sang Huh ◽  
Sang Yong Lee ◽  
Sang Hyuk Kim ◽  
...  
Keyword(s):  
High Speed ◽  
Infrared Imaging ◽  
Imaging System ◽  
Natural Diamond ◽  
Precision Machining ◽  
Maximum Deformation ◽  
Copper Pipe ◽  
High Speed Rotation ◽  
Ultra Precision ◽  
The Stability

The Winston cone baffle was developed for the space observation camera of the MIRIS (Multi-purpose Infrared Imaging System) which is the main payload of STSAT-3 (Science and Technology Satellite). The Winston cone baffle reduces the orbital heat load to the STSAT-3 and is thermally connected to the radiator to cool down. The jig and ultra precision machining jig was designed using a 3D modelling program and analyzed using a computer aided engineering program (ANSYS). The reasons for designing the jig for the baffle were to enhance the stability of the machining and improve the form accuracy of the baffle. The strength, weight and barycentre of the jig are investigated to find the optimized ultra precision machining conditions. To maintain the weight balance of the baffle at high speed rotation, there are lots of holes that can be inserted by heavier bolts. Vibration of the natural diamond bite tool is reduced by using thin copper pipe and urethane silicone. Using this bite tool, we could decrease patterns on the surface of the Winston cone baffle. The results of the simulation using ANSYS show that maximum deformation of the baffle is less than the tolerance limit. Surface roughness of the fabricated Winston cone baffle is machined with the jig and the machining tool is under 5 nm. The Winston cone baffle is plated with gold after being electroless plated with nickel. This baffle is applied to the flight model of the MIRIS.

scholarly journals Effects of Water Inrush from Tunnel Excavation Face on the Deformation and Mechanical Performance of Shield Tunnel Segment Joints

2017 ◽  
Vol 2017 ◽  
pp. 1-18 ◽  
Author(s):  
Tingsheng Zhao ◽  
Wen Liu ◽  
Zhi Ye
Keyword(s):  
Mechanical Performance ◽  
Coupling Effect ◽  
Water Inrush ◽  
Bending Moment ◽  
Sharp Decrease ◽  
Shield Tunnel ◽  
Cross Sectional ◽  
Tunnel Excavation ◽  
Water Head ◽  
Control Criterion

Water inrush from the excavation face often occurs in the current shield construction of metro tunnels. In this study, the discontinuity of shield tunnel lining and the interaction between the tunnel segments, the grouting layer, and the surrounding rock are considered. Based on the 3D nonlinear contact theory, a hybrid model of the shield tunnel is constructed. Considering the fluid-solid coupling effect of water and soil, the influences of different water head differences on the mechanical performance and deformation of segments and joints in the shield tunnel are studied. The water gushing from the excavation face leads to vertical convergence of the cross-sectional area of the shield tunnel, and joint opening and dislocation result in sharp decrease of the waterproof capacity of joints. Meanwhile, the stress in the vicinity of segment joints increases sharply, and local cracks occur in the segment lining. The axial force, shear force, and bending moment in the joint bolt are also significantly increased. Based on the current metro standard and the computational results in this study, an emergency control criterion is put forward by means of controlling the discharge of water: the water head difference over the excavation face is required less than 4.6 M.

Influence of laterally loaded sleeved piles and pile groups on slope stability

2001 ◽  
Vol 38 (3) ◽  
pp. 553-566 ◽  
Author(s):  
C WW Ng ◽  
L M Zhang ◽  
K KS Ho
Keyword(s):  
Slope Stability ◽  
Dimensional Analysis ◽  
High Speed ◽  
Slope Failure ◽  
Load Transfer ◽  
Large Diameter ◽  
Three Dimensional ◽  
Pile Groups ◽  
The Stability ◽  
Laterally Loaded

Many high-rise buildings, bridges, and transmission towers are constructed on steep slopes in Hong Kong and are supported by large-diameter piles. These structures may be subjected to large lateral loads, such as those caused by typhoons, earthquakes, and high-speed vehicles. The margin of safety of the slope may decrease as a result of stresses transferred from the piles to the slope. To minimize the transfer of lateral load from the buildings to the shallow depths of the slope, an annulus of compressible material (sleeving) is sometimes formed between the piles and the adjacent soils. In this paper, a three-dimensional analysis is carried out to investigate the effects of unsleeved and sleeved single piles and pile groups on the stability of a cut slope. Mechanisms of load transfer from the piles to the slope are studied. The stability of the slope is evaluated using the strength reduction technique. The evolution of slope failure is examined and the factors of safety for both initiation of instability and global failure of the slope are identified from the numerical analyses. The sleeving technique is found to be capable of significantly reducing the stresses in the shallow depths of the slope in front of the piles, thus improving the local stability of the slope, but offers limited benefit with respect to global stability.Key words: laterally loaded pile and pile group, sleeving, slope stability, three-dimensional analysis, load transfer mechanism, factor of safety.

Study on the pin Track of Four-Bar Linkage with Clearances

2011 ◽  
Vol 120 ◽  
pp. 329-334
Author(s):  
Ying Cai Yuan ◽  
Yan Li ◽  
Xin Liu
Keyword(s):  
Mechanical System ◽  
High Speed ◽  
Mechanical Performance ◽  
Kinematics And Dynamics ◽  
Dynamics Model ◽  
The Stability ◽  
Center Track ◽  
Pin Track ◽  
Four Bar Linkage

The pair clearance is inevitably exists in the mechanical system. With the speed of mechanical system increasing, clearance does harm to the stability and precision of mechanical system. Using four-bar linkage as the example to research the clearances’ characters, a dynamics model is established based on the kinematics and dynamics relations of the mechanism. Through the dynamics model, the track of pin center to collar in pair can be gotten. The irregularity of pin center track is related to the clearance and velocity and seriously influences the mechanical performance. So, it has to pay more attention to the clearance, especially in high speed.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽  
2009 ◽  
Vol 8 (1) ◽  
pp. 20-26 ◽  
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
Experimental Design ◽  
High Speed ◽  
Statistical Study ◽  
Process Variables ◽  
High Speeds ◽  
The Stability ◽  
Air Removal ◽  
Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

LANDSLIDE RISK MANAGEMENT IN THE COASTAL ZONE OF THE KUIBYSHEV RESERVOIR DUE THE DESIGN OF HIGH-SPEED LINE "MOSCOW-KAZAN"

2017 ◽  
Author(s):  
Nikolai Petrov ◽  
Nikolai Petrov ◽  
Inna Nikonorova ◽  
Inna Nikonorova ◽  
Vladimir Mashin ◽  
...  
Keyword(s):  
High Speed ◽  
Computational Models ◽  
Stable State ◽  
Landslide Risk ◽  
Kuibyshev Reservoir ◽  
Stepped Surface ◽  
The Stability ◽  
Landslide Slope ◽  
The Village

High-speed railway "Moscow-Kazan" by the draft crosses the Volga (Kuibyshev reservoir) in Chuvashia region 500 m below the village of New Kushnikovo. The crossing plot is a right-bank landslide slope with a stepped surface. Its height is 80 m; the slope steepness -15-16o. The authors should assess the risk of landslides and recommend anti-landslide measures to ensure the safety of the future bridge. For this landslide factors have been analyzed, slope stability assessment has been performed and recommendations have been suggested. The role of the following factors have been analyzed: 1) hydrologic - erosion and abrasion reservoir and runoff role; 2) lithologyc (the presence of Urzhum and Northern Dvina horizons of plastically deformable rocks, displacement areas); 3) hydrogeological (the role of perched, ground and interstratal water); 4) geomorphological (presence of the elemental composition of sliding systems and their structure in the relief); 5) exogeodynamic (cycles and stages of landslide systems development, mechanisms and relationship between landslide tiers of different generations and blocks contained in tiers). As a result 6-7 computational models at each of the three engineering-geological sections were made. The stability was evaluated by the method “of the leaning slope”. It is proved that the slope is in a very stable state and requires the following measures: 1) unloading (truncation) of active heads blocks of landslide tiers) and the edge of the plateau, 2) regulation of the surface and groundwater flow, 3) concrete dam, if necessary.

Dynamic Performance of High-Speed Electric Multiple Unit within Multi-Body System Simulation

2019 ◽  
Vol 12 (4) ◽  
pp. 339-349
Author(s):  
Junguo Wang ◽  
Daoping Gong ◽  
Rui Sun ◽  
Yongxiang Zhao
Keyword(s):  
High Speed ◽  
Rapid Development ◽  
Dynamic Performance ◽  
Body System ◽  
High Speed Railway ◽  
Evaluation Indexes ◽  
Actual Operation ◽  
Multiple Unit ◽  
The Stability ◽  
Multi Body

Background: With the rapid development of the high-speed railway, the dynamic performance such as running stability and safety of the high-speed train is increasingly important. This paper focuses on the dynamic performance of high-speed Electric Multiple Unit (EMU), especially the dynamic characteristics of the bogie frame and car body. Various patents have been discussed in this article. Objective: To develop the Multi-Body System (MBS) model of EMU, verify whether the dynamic performance meets the actual operation requirements, and provide some useful information for dynamics and structural design of the proposed EMU. Methods: According to the technical characteristics of a typical EMU, a MBS model is established via SIMPACK, and the measured data of China high-speed railway is taken as the excitation of track random irregularity. To test the dynamic performance of the EMU, including the stability and safety, some evaluation indexes such as wheel-axle lateral forces, wheel-axle lateral vertical forces, derailment coefficients and wheel unloading rates are also calculated and analyzed in detail. Results: The MBS model of EMU has better dynamic performance especially curving performance, and some evaluation indexes of the stability and safety have also reached China’s high-speed railway standards. Conclusion: The effectiveness of the proposed MBS model is verified, and the dynamic performance of the MBS model can meet the design requirements of high-speed EMU.

scholarly journals Mechanical Performance of a Ballastless Track System for the Railway Bridges of High-Speed Lines: Experimental and Numerical Study under Thermal Loading

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2876
Author(s):  
Yingying Zhang ◽  
Lingyu Zhou ◽  
Akim D. Mahunon ◽  
Guangchao Zhang ◽  
Xiusheng Peng ◽  
...  
Keyword(s):  
High Speed ◽  
Thermal Loading ◽  
Mechanical Performance ◽  
Track Structure ◽  
Box Girder ◽  
High Speed Railway ◽  
Ballastless Track ◽  
Track System ◽  
Girder Bridge ◽  
Track Slab

The mechanical performance of China Railway Track System type II (CRTS II) ballastless track suitable for High-Speed Railway (HSR) bridges is investigated in this project by testing a one-quarter-scaled three-span specimen under thermal loading. Stress analysis was performed both experimentally and numerically, via finite-element modeling in the latter case. The results showed that strains in the track slab, in the cement-emulsified asphalt (CA) mortar and in the track bed, increased nonlinearly with the temperature increase. In the longitudinal direction, the zero-displacement section between the track slab and the track bed was close to the 1/8L section of the beam, while the zero-displacement section between the track slab and the box girder bridge was close to the 3/8L section. The maximum values of the relative vertical displacement between the track bed and the bridge structure occurred in the section at three-quarters of the span. Numerical analysis showed that the lower the temperature, the larger the tensile stresses occurring in the different layers of the track structure, whereas the higher the temperature, the higher the relative displacement between the track system and the box girder bridge. Consequently, quantifying the stresses in the various components of the track structure resulting from sudden temperature drops and evaluating the relative displacements between the rails and the track bed resulting from high-temperature are helpful in the design of ballastless track structures for high-speed railway lines.

Sign in / Sign up

Export Citation Format

Share Document