scholarly journals Subsurface settlements of shield tunneling predicted by 2D and 3D constitutive models considering non-coaxiality and soil anisotropy: a case study

2021 ◽  
Author(s):  
Yong Fang ◽  
Jian Cui ◽  
Dariusz Wanatowski ◽  
Nikolaos Nikitas ◽  
Ran Yuan ◽  
...  
Keyword(s):  
High Speed ◽  
Field Data ◽  
Constitutive Models ◽  
Surface Settlement ◽  
Shield Tunnel ◽  
Initial Stiffness ◽  
Initial Soil ◽  
Cross Anisotropy ◽  
Surface Settlements ◽  
2D And 3D

Appropriate constitutive models and reliable excavation and support sequences are believed to be the major concern in using Finite element (FE) analysis to simulate shield tunnel excavation. This paper presents systematic 2D and 3D FE analyses employing a number of constitutive models accounting for initial soil anisotropy and non-coaxial plasticity, as evidenced within site investigations from the Tsinghuayuan Tunnel of the Jing-Zhang High-Speed Railway in China. The aim is to assess the effects of both the initial soil anisotropy and non-coaxiality on longitudinal and transverse tunneling-induced surface settlements. It is shown that the excavation procedures combined with the degree of cross-anisotropy are key towards the accurate prediction of maximum vertical displacements from tunneling, matching field data. Knowledge of the initial soil strength anisotropy can further improve the shape prediction of the transverse tunneling-induced surface settlement troughs. When considering n = 0.6 and "β =" 〖" 0" 〗^"°" in simulations, the transverse surface settlement trough obtained is almost coincided with monitored field data. Initial stiffness anisotropy used in the prediction of shield tunnel-induced surface settlements in sandy pebble soils, does improve realism of results significantly. The maximum longitudinal settlement predicted by considering cross-anisotropy is larger than that predicted by its isotropic counterpart.

scholarly journals Prediction of Ground Settlement Induced by Slurry Shield Tunnelling in Granular Soils

2020 ◽  
Vol 6 (12) ◽  
pp. 2273-2289
Author(s):  
Mo'men Ayasrah ◽  
Hongsheng Qiu ◽  
Xiedong Zhang ◽  
Mohammad Daddow
Keyword(s):  
High Speed ◽  
Phase 1 ◽  
Field Measurements ◽  
Tunnel Boring Machine ◽  
Surface Settlement ◽  
Shield Tunnel ◽  
Tunnel Excavation ◽  
Theoretical Approaches ◽  
Geotechnical Investigations ◽  
Slurry Shield

Underground structures play an important role in achieving the requirements of rapid urban development such as tunnels, parking garages, facilities, etc. To achieve what is needed, new transportation methods have been proposed to solve traffic congestion problems by using of high-speed railway and subway tunnels. One of the issues in urban spaces due to tunnel excavation is considerable surface settlements that also induce problems for surface structures. There are a variety of published relationships concerned with field measurements and theoretical approaches to evaluating the amount of the maximum surface settlement value due to tunneling. This paper studies the ground surface settlement caused by the Greater Cairo Metro – Line 3 - Phase-1. This project was constructed by a slurry shield Tunnel Boring Machine (TBM). Therefore, this work consists of two parts. The first part presents the details of the project and monitoring results field and laboratory geotechnical investigations in order to determine the soil properties. The second part is to the comparison between the field measurements and theoretical approaches for surface settlement due to tunneling construction. At the end of the works, the results show that the more convenient methods which approach the field measurements, and the major transverse settlement occurs within the area about 2.6 times the diameter of the tunnel excavation. Doi: 10.28991/cej-2020-03091617 Full Text: PDF

Assessment of two different constitutive models in High Speed Forming

2019 ◽  
Author(s):  
Andrey Brezolin ◽  
Tiago dos Santos ◽  
Pedro Rosa ◽  
Evandro Paese ◽  
Martin Geier ◽  
...  
Keyword(s):  
High Speed ◽  
Constitutive Models ◽  
High Speed Forming

scholarly journals Simulation of flow development in high-speed combustor in 2D and 3D formulations

2018 ◽  
Author(s):  
V. V. Vlasenko ◽  
E. S. Matyash ◽  
S. S. Molev ◽  
V. A. Sabelnikov ◽  
V. A. Talyzin
Keyword(s):  
High Speed ◽  
Flow Development ◽  
2D And 3D

scholarly journals Numerical Modeling of Masonry-infilled RC Frame

2019 ◽  
Vol 13 (1) ◽  
pp. 135-148 ◽  
Author(s):  
Christiana A. Filippou ◽  
Nicholas C. Kyriakides ◽  
Christis Z. Chrysostomou
Keyword(s):  
Cyclic Loading ◽  
Numerical Model ◽  
Constitutive Models ◽  
Control Analysis ◽  
Rc Frame ◽  
Initial Stiffness ◽  
Element Analysis ◽  
Rc Frames ◽  
Rc Frame Structures ◽  
Infilled Rc Frames

Background: The behavior of masonry-infilled Reinforced Concrete (RC) frame structures during an earthquake, has attracted the attention of structural engineers since the 1950s. Experimental and numerical studies have been carried out to investigate the behavior of masonry-infilled RC frame under in-plane loading. Objective: This paper presents a numerical model of the behavior existing masonry-infilled RC frame that was studied experimentally at the University of Patra. The objective of the present study is to identify suitable numerical constitutive models for each component of the structural system in order to create a numerical tool to model the masonry infilled RC frames in-plane behavior by accounting the frame-infill separation. Methods: A 2D masonry-infilled RC frame was developed in DIANA Finite Element Analysis (FEA) software and an eigenvalue and nonlinear structural cyclic analyses were performed. It is a 2:3 scale three-story structure with non-seismic design and detailing, subjected to in-plane cyclic loading through displacement control analysis. Results: There is a good agreement between the numerical model and experimental results through a nonlinear cyclic analysis. It was found that the numerical model has the capability to predict the initial stiffness, the ultimate stiffness, the maximum shear-force capacity, cracking- patterns and the possible failure mode of masonry-infilled RC frame. Conclusion: Therefore, this model is a reliable model of the behavior of masonry-infilled RC frame under cyclic loading including the frame-infill separation (gap opening).

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.

3D angle decomposition for elastic reverse time migration

Geophysics ◽  
2017 ◽  
Vol 82 (5) ◽  
pp. S377-S389
Author(s):  
Yuting Duan ◽  
Paul Sava
Keyword(s):  
Field Data ◽  
Time Lag ◽  
Image Point ◽  
Reverse Time ◽  
Reverse Time Migration ◽  
Converted Wave ◽  
The Third ◽  
Time Migration ◽  
Straight Lines ◽  
2D And 3D

We have developed three approaches for 3D angle decomposition using elastic reverse time migration. The first approach uses time- and space-lag common-image point gathers computed from elastic wavefields. This method facilitates computing angle gathers at sparse and possibly irregularly distributed points in the image. The second approach transforms extended time-lag images to the angle domain using slant stacks along 4D surfaces, instead of using slant stacks along 2D straight lines. The third approach transforms space-lag common-image gathers to the angle domain. The three proposed methods solve a system of equations that handles dipping reflectors, and they yield angle gathers that are more accurate compared with those obtained via alternative existing methods. We have developed our methods using 2D and 3D synthetic and field data examples and found that they provide accurate opening and azimuth angles and they can handle steeply dipping reflectors and converted wave modes.

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