scholarly journals Investigation on the Surface Settlement for Curved Shield Construction in Sandy Stratum with Laboratory Model Test

2021 ◽  
Author(s):  
Ping Xu ◽  
Danhui Xi
Keyword(s):  
Similarity Theory ◽  
Surface Settlement ◽  
Small Radius ◽  
Shield Tunnel ◽  
Laboratory Model ◽  
Curvature Radius ◽  
Small Curvature ◽  
Practical Engineering ◽  
Turning Radius ◽  
Laboratory Model Test

Abstract According to the existing practical engineering data, the settlement curve of shield tunnel with small curvature radius is obviously different from that of straight tunnel, so using Peck formula to forecast the surface settlement is not applicable. This paper describes results from a series of the laboratory test based on similarity theory carried out in sandy soil. According to the test results, the characteristics of surface settlement caused by small radius tunnel excavation are summarized, and the effects of turning radius and buried depth on the surface settlement are demonstrated. Based on Gaussian formula, a method to forecast the surface settlement caused by construction of shield tunnel with small curvature radius is developed.

Laboratory Model Test on Foundation Reinforcement by Locating Lime-Soil Pileat both Side of Strip Footing

2012 ◽  
Vol 170-173 ◽  
pp. 740-742
Author(s):  
Ji Zhou ◽  
Xi Yuan Liu ◽  
Yuan Ming Dou
Keyword(s):  
Bearing Capacity ◽  
Model Test ◽  
Similarity Theory ◽  
Strengthening Mechanism ◽  
Strip Footing ◽  
Laboratory Model ◽  
Before And After ◽  
S Curve ◽  
Laboratory Model Test

Using similarity theory as guidance ,the paper designs the laboratory model test on foundation reinforcement by locating lime-soil pile at both side of strip footing, and researches foundation bearing capacity, p-s curve, the magnitude and distribution discipline of the foundation stress before and after reinforcement, and analyzes the load-bearing mechanism, strengthening mechanism and reinforcement effect of the strengthening technology. The results show that the lime-soil pile can effectively improve the foundation bearing capacity, and reduce the amount of ground settlement; under the role of the lime-soil pile, the stress spread lesser to the outside of pile in the ground, and causes the foundation stress to the deeper place.

Experimental Study on Non-Perpendicular Frame Structure of Tall Building

2008 ◽  
Vol 400-402 ◽  
pp. 593-598
Author(s):  
Wei Xing Shi ◽  
Cheng Qing Liu ◽  
Xi Lin Lu ◽  
Song Zhang ◽  
Ying Zhou
Keyword(s):  
Similarity Theory ◽  
Structural Type ◽  
Shaking Table ◽  
Frame Structure ◽  
Scale Model ◽  
Prototype Structure ◽  
Table Model ◽  
Practical Engineering ◽  
Whiplash Effect ◽  
Shaking Table Model Test

A shaking table model test is conducted for Guangzhou West Tower to study its seismic behavior in State Key Laboratory for Disaster Reduction in Civil Engineering at Tongji University. Guangzhou West Tower adopts a new structure system and the significant characteristic of this system is the non-perpendicular frame arranged around the building, acting both as columns and bracings. Based on the similarity theory and member equivalent principle，a 1/80 scale model of this building is made of polymethyl methacrylate(PMMA). The model’s dynamic characteristics, earthquake-resistant behavior, responses of acceleration and deformation under different wave peak values are investigated, then the seismic responses of the prototype structure are deduced and analyzed. The whiplash effect of the prototype structure is studied, and the weak position of the structure is found out. The experiment results demonstrate that it is feasible to apply this structural type to practical engineering. Finally, some suggestions for the engineering design of the prototype structure are put forward.

scholarly journals Experimental study on dynamic response of model shield tunnel induced by moving-axle loads of subway train

2018 ◽  
Vol 14 (10) ◽  
pp. 155014771880278
Author(s):  
Mengxi Zhang ◽  
Xiaoqing Zhang ◽  
Lei Li ◽  
Chengyu Hong
Keyword(s):  
Time History ◽  
Vertical Displacement ◽  
Wheel Speed ◽  
Dynamic Responses ◽  
Scale Model ◽  
Shield Tunnel ◽  
Laboratory Model ◽  
Cover Depth ◽  
Axle Loads ◽  
Subway Train

A new testing method was introduced to apply moving-axle loads of a subway train on a track structure. In order to investigate the dynamic responses of the shield tunnel subjected to moving-axle loads, a series of laboratory model tests were conducted in a 1/40 scale model tunnel. The influences of the axle load, the wheel speed, and the cover depth of the shield tunnel on the vertical displacement and acceleration of the lining were presented and discussed. Parametric studies revealed that the vertical displacement–time history of the lining presents a “W” shape due to the combined action of two axles of a bogie. The peak value of the vertical displacement increased with the axle load linearly, while it decreased with the increase in the cover depth. Moreover, response time of the displacement decreased with the increase in the wheel speed, but the peak values remained stable at the same level. Finally, a three-dimensional dynamic finite element model was adopted to simulate the movement of the axle loads and calculate the responses of the lining. The numerical results analysis agrees well with experimental results.

scholarly journals Strain and Curvature Stability Enhanced SMF Introduction

2017 ◽  
Vol 6 (1) ◽  
pp. 63
Author(s):  
S. Makouei
Keyword(s):  
Refractive Index ◽  
Optical Fiber ◽  
Design Method ◽  
Single Mode ◽  
Effective Area ◽  
Refractive Index Profile ◽  
Curvature Radius ◽  
Geometrical Parameters ◽  
Small Curvature ◽  
Bending Loss

In this paper, the strain insensitive single mode optical fiber with low nonlinear effects and ultra low bending loss (BL), appropriate for small curvature radius installation, is presented. The suggested design method is based on the reverse engineering which evaluates the refractive index profile considering proper mode field diameter (MFD) value. Then, so as to attain the desired bending loss and strain response for the optical fiber, the optimization tool of the evolutionary genetic algorithm (GA) is employed to determine the optical and geometrical parameters of the structure. In the first designed fiber, the calculations for BL, MFD, effective area (Aeff), and effective refractive index (neff) sensitivity to strain in the well-known wavelength of 1.55 µm are 0.0018 dB per each turn of 5 mm curvature radius, 8.53 µm, 58 µm2, and 4.5 × 10-8 µɛ-1, respectively. Furthermore, the effect of placing raised outer cladding in the fiber structure is investigated which exhibits the MFD of 8.63 µm, 0.0093 dB BL for single turn of 5 mm radius, and 87 µm2 Aeff at 1.55 µm. In this case the strain sensitivity of 6.7 × 10-8 µɛ-1 is calculated for the neff. The mentioned effective area is magnificently large in the domain of bend insensitive fibers. In the meantime, the designed structures are insensitive to strain which is a crucial feature in applications with small curvature radius.

Surface Settlement and Influence on Xi’an City Wall due to Xi’an Subway Line 2 Tunnel Construction

2011 ◽  
Vol 374-377 ◽  
pp. 2326-2332
Author(s):  
Jun Lian Li ◽  
Jian Guo Zheng ◽  
Yang Ping Yao
Keyword(s):  
Surface Settlement ◽  
Shield Tunnel ◽  
Tunnel Construction ◽  
The South ◽  
Protective Measures ◽  
City Wall ◽  
Calculation Results ◽  
Settlement Ratio ◽  
Grouting Reinforcement ◽  
Xi’An City

This paper refers the case project of the Xi'an Subway Line 2 tunneling through the South Gate area of the Xi'an City Wall, has researched the surface settlement due to tunnel construction, and simulated the whole shield tunnel by using Flac3D numerical analysis. This paper has obtained the law of surface settlement and the influence on the City Wall in the tunnel construction by analyzing the calculation results, and simulated the effects of three protective measures which will be used in the South Gate area. The results showed that the surface settlement ratio after the piles and chemical grouting reinforcement was lower by about 25% than no reinforcement. The monitoring data showed that the result of model calculation was reasonable, and the protective measures in Condition 3 are feasible and effective.

scholarly journals Studying and improving intermediate rail fastening of rail transport

2019 ◽  
Vol 109 ◽  
pp. 00028
Author(s):  
Volodymyr Hovorukha
Keyword(s):  
Rail Transport ◽  
Railway Track ◽  
Small Radius ◽  
Working Capacity ◽  
Operational Parameters ◽  
Transverse Loading ◽  
Topical Problem ◽  
Railroad Transport ◽  
Small Curvature ◽  
Horizontal Loading

Topical problem concerning the improvement of intermediate rail fastening of a railway track of railroad transport as well as industrial and underground rail one has been considered taking into account peculiarities of operation in terms of curved sections of a route with small-radius curvature. Objective of the paper is to improve operational parameters of a railway track with extra small curvature radii in terms of railroad gauge adjustment. Operation of the components of intermediate rail fastening, being subject to intense wear and destruction due to the effect of great transverse and horizontal loading within the curved route sections with small-radius curvature, has been and analysed. Innovative engineering solutions to improve intermediate rail fastening have been proposed. Such peculiarity of the device of intermediate rail fastening provides increased durability and working capacity of rail fastening components in terms of considerable transverse loading within the route sections with small-radius curvature. The obtained results may be applied for underground and industrial rail transport as well as for railroad one.

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