Numerical Analysis of Segmental Tunnel Linings employing a Hybrid Modeling Approach
Andreas-Nizar
Granitzer
Institute of Soil Mechanics, Foundation Engineering and Computational Geotechnics, Graz University of Technology, Austria
author
Franz
Tschuchnigg
Institute of Soil Mechanics, Foundation Engineering and Computational Geotechnics, Graz University of Technology, Austria
author
text
article
2021
eng
The structural performance of shield-driven tunnel linings is considerably affected by the existence of segmental joints. Nevertheless, segmental tunnel linings are commonly modelled as isotropic structures in engineering practice, thereby ignoring the joint-induced stiffness reduction in numerical analysis. A more realistic approach is to consider the tunnel structure as continuous ring with adjusted rigidities which is also referred to as indirect-joint model. However, this modeling approach is a complicated task since it requires the definition of anisotropic stiffness parameters. In this context, the present paper introduces a hybrid modeling approach, which combines analytical solutions and numerical studies. Based on extensive numerical studies, anisotropic stiffness parameters are defined to model an existing drainage tunnel (SDT). Finally, a case study is discussed, where the developed indirect-joint model is used to investigate the structural response of the SDT. In this context, particular emphasis is placed on the deformation of the tunnel crown developing throughout the entire construction phase.
Computational Engineering and Physical Modeling
Pouyan Press
2588-6959
4
v.
1
no.
2021
1
18
https://www.jcepm.com/article_122041_76b2c6642e619b5bc5097fb3d2fffbf7.pdf
dx.doi.org/10.22115/cepm.2021.247314.1130
Comparative Three-Dimensional Finite Element Analysis of Piled Raft Foundations
Alireza
Abdolrezayi
Geotechnical Engineer, Department of Civil Engineering, University of Tehran, Tehran, Iran
author
Navid
Khayat
Department of Civil Engineering, Islamic Azad University, Ahvaz branch, Ahvaz, Iran
author
text
article
2021
eng
3-dimensional finite element method as a general method to solve complex problems is one of the most powerful numerical methods which can be used for piled raft foundation analysis. These models can consider the complex interaction between soil and structure. Among available 3D FEM software for modelling pield raft foundations, in this paper MIDAS GTS is used due to its various element type and modeling abilities. In this article, different pile modeling techniques in MIDAS GTS software (like pile modeling by solid elements, modeling by beam elements connected to soil elements and modeling by EPM ) are compared with a real pile loading test data. Results showed that all three methods have excellent compatibility with the results of loading test in the linear area of the load-settlement curve, and SEM and EPM kept their conformity further in the non-linear area as well. One of the most critical problems in 3D FEM modeling process of piled raft foundations with SEM was an increase in the number of elements when the number of piles increases and that leads to model's slowness and convergence problem. Piles modeling by EPM needs much lower elements; using this method, skin friction resistance, tip resistance and displacement between pile and soil can be easily calibrated with a pile loading test data which facilitates piled raft analysis with a large number of piles. After comparing different pile modeling techniques through MIDAS GTS software, the ability of the software for modeling piled raft foundations had been verified; Results show acceptable agreement between software output and monitored values and also outputs from other methods and software.
Computational Engineering and Physical Modeling
Pouyan Press
2588-6959
4
v.
1
no.
2021
19
36
https://www.jcepm.com/article_115532_8c7394894fb24b8312b729b38198c234.pdf
dx.doi.org/10.22115/cepm.2020.234834.1111
Cost Analysis of a Large Solar Plant with Parabolic Trough Concentrators Using Molten Salt Storage Tank
Mohamed
Mohamed
Mechanical Power Dept., Faculty of Engineering, Mattaria, Helwan University, Cairo, Egypt
author
Abd El-Nabi
El-Sayed
High Institute of Engineering, Elshorouk Academy, Cairo, Egypt
author
Khairy
Megalla
Mechanical Power Dept., Faculty of Engineering, Mattaria, Helwan University, Cairo, Egypt
author
Hassan
Elattar
Department of Mechanical Engineering, Benha Faculty of Engineering, Benha University, Benha, Egypt
author
text
article
2021
eng
Thermal storage tank is a standout amongst the most encouraging methods in solar thermal power stations operation. Accurate selection of appropriate storage system is a significant parameter to ensure the continuous working of thermal solar station during the absence of the sun. This work describes financial analysis of different locations of a 500MW Solar Plant in Egypt and also thermal tank design. The selected three locations which are investigated in this study are Aswan, EL-Arish and Hurghada to build this challenged size solar station. These locations cover the tree levels of the solar intensity in Egypt. This study is achieved by System Advisor Model (SAM) as financial analysis simulation tool. All the solar thermal power plants are working twenty-four hours per day and with sixteen full load hours of thermal energy storage (TES). Parametric design and cost analysis for each location, comparison between these locations are introduced to select the optimum location for 500MW solar power plant. The results of this study is considered a good orientation for feasibility study for CPS (concentrators parabolic system) projects, and it is needed in all over the world in particular, in Egypt for future to produce clean energy.
Computational Engineering and Physical Modeling
Pouyan Press
2588-6959
4
v.
1
no.
2021
37
55
https://www.jcepm.com/article_122043_9807e2a9f33c331126347b668f8e0c77.pdf
dx.doi.org/10.22115/cepm.2021.240381.1120
Characteristic Properties of Concrete with Recycled Burnt Bricks as Coarse Aggregates Replacement
Sunday
Azunna
Civil Works Department, Ringo Star Ventures Ltd, 34 Panama Street Ministers Hill, Maitama, Abuja, Nigeria
author
Joseph
Ogar
Department of Civil Engineering, Faculty of Engineering, Federal Polytechnic Bauchi, Bauchi, Nigeria
author
text
article
2021
eng
To counter the depletion of river sand and to reduce the menace caused by disposal of crushed brick wastes, the use of crushed bricks to produce a more environmentally sustainable and economical concrete is explored. This project studied the properties of concrete made using crushed burnt bricks as an aggregate in comparison with concrete made using natural coarse aggregates. Experimental investigation was carried on the concrete in its wet and dry state to determine the durability and mechanical properties of the concrete by testing the workability, water absorption, density and compressive strength test of the concrete. The result of the water absorption test shows that concretes made using crushed burnt bricks as coarse aggregates absorbed more water with value of 7.83% than conventional concrete with value of 2.83% at 28 days curing. The strength test result carried out indicates that conventional concrete at 28 days has strength of 22.96 N/mm2 higher than that of concretes made using crushed burnt bricks at 28 days of curing with value of 15.45 N/mm2, however, the strength of concretes from crushed burnt bricks still lies within the acceptable limit. Other test carried out on the crushed burnt aggregates to ascertain their suitability were, Aggregates Impact Value test (AIV) with value at 15.68% and Aggregates Crushing Value test (ACV) with value at 23.36%. The properties and quality of the crushed burnt bricks aggregates were also determined.
Computational Engineering and Physical Modeling
Pouyan Press
2588-6959
4
v.
1
no.
2021
56
72
https://www.jcepm.com/article_122044_fe8732563e767bd4835ff83806e9c62c.pdf
dx.doi.org/10.22115/cepm.2021.245270.1126
The Relation between Deposited Weight and Quality of Coating in EPD Method Derived by Genetic Programming
Mohammad Sadegh
Shakeri
Materials and Energy Research Center (MERC), P.O. Box 31779-83634, Karaj, Iran
author
text
article
2021
eng
In this work, the relation between deposited weight and the quality of electrophoretically deposited coating has been derived using genetic programming method. Although, the accumulated mass is thicken by time, its quality varies at different times of coating procedure. Three different suspensions i.e. Mullite, SiC and Mullite/SiC were stabled in ethanol medium and the suspended particles were electrophoretically deposited on C-C composite at several different times. The results of SEM micrographs show that the quality of coating rises by time and after some time it starts to drop for all three suspensions. The results of Zeta potential of suspension after different times of coating that is derived by pH measurement, illustrate the same pattern. There is a maximum for zeta potential after 150 sec of deposition process. Accordingly, the quality of coating rises as a result of enhancement of Zeta potential in suspensions. Last but not least, there is a relation between deposition time and quality of coating which is mathematically modeled using genetic programming method. In this case, the root of multiplication of Z-w and w-t differential equations could show the optimum time of deposition process.
Computational Engineering and Physical Modeling
Pouyan Press
2588-6959
4
v.
1
no.
2021
73
83
https://www.jcepm.com/article_115533_dec670a886f87b244c284efb3dc0efb4.pdf
dx.doi.org/10.22115/cepm.2020.239389.1117
Effect of Threshold Twin Volume Fraction in Crystal Plasticity Modeling
FaYong
Li
College of Materials Science and Engineering, Chongqing University, Chongqing, China
author
Adrien
Chapuis
College of Materials Science and Engineering, Chongqing University, Chongqing, China
author
Qing
Liu
College of Materials Science and Engineering, Chongqing University, Chongqing, China
author
text
article
2021
eng
Modeling of metals deforming by twinning requires reorienting the matrix into twin orientation. In twinning models like the Predominant Twin Reorientation scheme (PTR), a threshold volume fraction is defined with an empiric equation to reorient the parent grain into the dominant twin variant. This equation contains two parameters which are first investigated in the present study, showing their effect on simulated flow stress and twin volume fraction evolution. Magnesium, with a tension and a compression twinning modes, is taken as an example to compare the expected experimental behavior and the modeled behavior. Complex deformations such as strain path change and multiple twinning are modeled with the PTR, and simulated stress, twin volume fraction and texture are correlated with the expected behavior. The PTR shows a good agreement with experiments when the twin volume fraction corresponds to the fraction of grains reoriented into twins, but limited predictability when the twinned grains are not reoriented.
Computational Engineering and Physical Modeling
Pouyan Press
2588-6959
4
v.
1
no.
2021
84
100
https://www.jcepm.com/article_122042_0ee7bfd18008990111fe5f2e5890dbe1.pdf
dx.doi.org/10.22115/cepm.2021.245719.1128