Due to the significant delay and cost associated with experimental tests, a model-based evaluatio... more Due to the significant delay and cost associated with experimental tests, a model-based evaluation of concrete compressive strength is of high value, both for the purpose of strength prediction as well as the mixture optimization. In contrast to the prior recent studies employing a single regression model, in this paper, we present a combined multi-model framework where the regression methods based on artificial neural network, random forest regression and polynomial regression are jointly implemented for compressive strength prediction with a higher accuracy. The outcomes of the individual regression models are combined via a linear weighting strategy and optimized over the training data set as a quadratic convex optimization problem. It is worth mentioning that due to the convexity of the formulated problem, the globally optimum weighting strategy is obtained via standard numerical solvers. Afterwards, employing the obtained regression model, a multi-objective genetic algorithm-based method is proposed for mixture optimization under practical constraints, where a Pareto front of the cost-CS trade-off has been obtained employing the available data set. Numerical evaluations show that the proposed multi-model regression achieves a significantly higher prediction accuracy, i.e., approximately 18% reduction in the obtained prediction mean squared error, without weight optimization, and roughly 30% reduction in the obtained prediction mean squared error with an optimized combination following a convex quadratic optimization, compared to the best single model regression method employing a multi-layered artificial neural network.
XI International Conference on Structural Dynamics
This paper deals with the effectiveness of various configurations of a geofoam-filled barrier inc... more This paper deals with the effectiveness of various configurations of a geofoam-filled barrier including single, double and triangle wall trenches in isolating the ground vibrations induced by a harmonic load. A 3D finite element program (Plaxis) is used and the model is verified by the result of the analytical solution for the active scheme. Furthermore, a comprehensive parametric study is performed to evaluate the effect of geometrical factors including the depth, width and the length for all systems. The main assumption during the parametric study is treating each parameter as an independent variable and keeping other parameters constant. A genetic algorithm is a proper tool for optimizing all key parameters that can have mutual effects on the vibration attenuation since the vibration isolation is a non-linear problem. A genetic algorithm code is implemented with the help of Python Software and Finite Element Program (Plaxis) for all three systems and the optimized parameters for reaching 75% efficiency of the barrier are calculated. The result of the parametric study showed that the single wall system needs the lowest value of normalized depth for reaching the highest value of the efficiency. Also, the mutual study of all parameters proved that the results are very different from a single para-metric study. The comparison of all systems demonstrated that a double wall barrier is the best system for different frequencies.
ICONHIC2022 - International Conference on Natural Hazards & Infrastructure, 2022
Studies on vibration isolation have attracted the attention of researchers for the last two decad... more Studies on vibration isolation have attracted the attention of researchers for the last two decades because they can have a significant effect on the comfort of occupants of the buildings located near the source. A typical assumption for the study of ground-borne vibration is considering soil as homogeneous, which is unrealistic in many real cases. Therefore, the main focus of this study is to find the effect of soil layering on the efficiency of geofoam-filled trenches. An automated and comprehensive parametric study has been performed by coupling Plaxis, Python and Matlab programs. The results of this automated parametric study allow the identification of the main governing parameters, which are location (𝑋) and depth (𝐷) of the trench and shear wave velocities of the soil (𝑉𝑠). Results showed that a depth of 𝐷 = 1 and 1.25 𝜆𝑟, is enough to have a successful active isolation system. In addition to this, the study shows that the trench is more efficient in soils with larger values of shear wave velocity (𝑉𝑠). The use of this automated process can also assist with similar parametric studies for other applications and during design of similar installations.
The recent researchers have discovered microtremor applications for evaluation of the liquefactio... more The recent researchers have discovered microtremor applications for evaluation of the liquefaction potential. Microtremor measurement is a fast, applicable and cost-effective method with extensive applications. In the present research the liquefaction potential has been reviewed by utilization of microtremor measurement results in Babol city. By using the fundamental frequency and amplification factor, the value of vulnerability index (Kg) was calculated and the liquefaction potential has been evaluated. For controlling the accuracy of this method, its output has compared with the results of Seed and Idriss method in 30 excavated boreholes within the study area. These two methods show an acceptable conformity with each other. Also, the artificial neural network (ANN) with different inputs was trained. Regarding the results of the three methods, we can conclude the threshold value of liquefaction potential is Kg=5. By reviewing and comparing these three methods, it will be observed t...
In this study, the seismic behavior of a shallow tunnel with square cross section is investigated... more In this study, the seismic behavior of a shallow tunnel with square cross section is investigated in a two layered and elastic heterogeneous environment using numerical method. To do so, FLAC finite difference software was used. Behavioral model of the ground and tunnel structure was assumed linear elastic. Dynamic load was applied to the model for 0.2 seconds from the bottom in form of a square pulse with maximum acceleration of 1 m/s<sup>2</sup>. The interface between the two layers was considered at three different levels of crest, middle, and bottom of the tunnel. The stiffness of the two upper and lower layers was considered to be varied from 10 MPa to 1000 MPa. Deformation of cross section of the tunnel due to dynamic load propagation, as well as the values of axial force and bending moment created in the tunnel structure, were examined in the three states mentioned above. The results of analyses show that heterogeneity of the environment, its stratification, and p...
Installation of stone columns is recognized as a usual procedure for the treatment for soft clay ... more Installation of stone columns is recognized as a usual procedure for the treatment for soft clay soils. In the current research, three-dimensional finite-element analyses were performed to simulate the behavior of multilayer geosynthetic-reinforced granular bed over stone column-reinforced soft soil using the ABAQUS. An extensive research was conducted for better understanding of the mechanism of load transfer in ordinary stone columns (OSCs) and geosynthetic-encased columns (GECs) installed under a concrete foundation. Parametric studies were also carried out to investigate the effects of factors such as hardness of the geosynthetic encasement and the region replacement proportion on the overall behaviour of the GECs group. The results designated that utilizing of more than one geosynthetic reinforcement with stone columns is not so effective to reduce the maximum settlement. But, a multilayer reinforcement system is efficient to decrease the maximum settlement when stone columns are not used. It was also shown that there is a large growth in the amount of stress concentration proportion with the presence of geosynthetic reinforcement in comparison with the amount when there is no geosynthetic reinforcement present.
This article analyses the reliability based on the deterministic method and acceleration attenuat... more This article analyses the reliability based on the deterministic method and acceleration attenuation in the Chalus City, as well as, obtaining the density function of probability distribution and statistics for cyclic stress ratio (CSR). The density function of probability distribution and the cycle resistance ratio (CRR) can be concluded from the possibility of the cycle of resistance curves. The proposed first-order, second-moment procedure is used to determine the relationship between three factors including, the probability of liquefaction, the safety factor and the reliability index. In this study, the numerical approach of genetic algorithm is utilized to minimize the function of the reliability index. The usage of genetic algorithm model provides a reliable mechanism suitable for a computer program. Two empirical relationships based on P L , \( N_{\text{SPT}} \), and CSR with a correlation coefficient and mean error of 95 and 10%, respectively, and the relationship between P ...
Due to the significant delay and cost associated with experimental tests, a model based evaluatio... more Due to the significant delay and cost associated with experimental tests, a model based evaluation of concrete compressive strength is of high value, both for the purpose of strength prediction as well as the mixture optimization. In this regard, several recent studies have employed state-of-the-art regression models in order to achieve a good prediction model, employing available experimental data sets. Nevertheless, while each of the employed models can better adapt to a specific nature of the input data, the accuracy of each individual model is limited due to the sensitivity to the choice of hyperparameters and the learning strategy. In the present work, we take a further step towards improving the accuracy of the prediction model via the weighted combination of multiple regression methods. Moreover, a heuristic Genetic Algorithm (GA)-based multi-objective mixture optimization is proposed, building on the obtained multi-regression model. In particular, we present a dataaided fram...
In this study, the seismic behavior of a shallow tunnel with square cross section is investigated... more In this study, the seismic behavior of a shallow tunnel with square cross section is investigated in a two layered and elastic heterogeneous environment using numerical method. To do so, FLAC finite difference software was used. Behavioral model of the ground and tunnel structure was assumed linear elastic. Dynamic load was applied to the model for 0.2 seconds from the bottom in form of a square pulse with maximum acceleration of 1 m/s 2. The interface between the two layers was considered at three different levels of crest, middle, and bottom of the tunnel. The stiffness of the two upper and lower layers was considered to be varied from 10 MPa to 1000 MPa. Deformation of cross section of the tunnel due to dynamic load propagation, as well as the values of axial force and bending moment created in the tunnel structure, were examined in the three states mentioned above. The results of analyses show that heterogeneity of the environment, its stratification, and positioning of the inte...
Abstract In this paper, considering the plain strain conditions, a numerical study has been condu... more Abstract In this paper, considering the plain strain conditions, a numerical study has been conducted to investigate the behavior of multi layer geosynthetic-reinforced granular bed overlying a soft soil using the Fast Lagrangian Analysis of Continua (FLAC) program. The ...
Background: During an earthquake, significant damage can result due to instability of the soil in... more Background: During an earthquake, significant damage can result due to instability of the soil in the area affected<br>by internal seismic waves. Liquefaction is known as one of the major causes of ground failure due to the<br>earthquake. Various procedures have been classified for assessing liquefaction phenomenon into two main groups,<br>including the deterministic and probabilistic approaches.<br>Results: Four deterministic methods and one probabilistic approach, which is a reliability procedure are considered for<br>assessing the liquefaction potential in Babol City. The main purpose of this comprehensive research is to evaluate the<br>liquefaction potential and to determine the validation and accuracy of the reliability approach. For this purpose, 60<br>boreholes including almost 600 field records in different parts of Babol City are analyzed and liquefaction and nonliquefaction areas are identified. Microzonation maps are provided by r...
Due to the significant delay and cost associated with experimental tests, a model-based evaluatio... more Due to the significant delay and cost associated with experimental tests, a model-based evaluation of concrete compressive strength is of high value, both for the purpose of strength prediction as well as the mixture optimization. In contrast to the prior recent studies employing a single regression model, in this paper, we present a combined multi-model framework where the regression methods based on artificial neural network, random forest regression and polynomial regression are jointly implemented for compressive strength prediction with a higher accuracy. The outcomes of the individual regression models are combined via a linear weighting strategy and optimized over the training data set as a quadratic convex optimization problem. It is worth mentioning that due to the convexity of the formulated problem, the globally optimum weighting strategy is obtained via standard numerical solvers. Afterwards, employing the obtained regression model, a multi-objective genetic algorithm-based method is proposed for mixture optimization under practical constraints, where a Pareto front of the cost-CS trade-off has been obtained employing the available data set. Numerical evaluations show that the proposed multi-model regression achieves a significantly higher prediction accuracy, i.e., approximately 18% reduction in the obtained prediction mean squared error, without weight optimization, and roughly 30% reduction in the obtained prediction mean squared error with an optimized combination following a convex quadratic optimization, compared to the best single model regression method employing a multi-layered artificial neural network.
XI International Conference on Structural Dynamics
This paper deals with the effectiveness of various configurations of a geofoam-filled barrier inc... more This paper deals with the effectiveness of various configurations of a geofoam-filled barrier including single, double and triangle wall trenches in isolating the ground vibrations induced by a harmonic load. A 3D finite element program (Plaxis) is used and the model is verified by the result of the analytical solution for the active scheme. Furthermore, a comprehensive parametric study is performed to evaluate the effect of geometrical factors including the depth, width and the length for all systems. The main assumption during the parametric study is treating each parameter as an independent variable and keeping other parameters constant. A genetic algorithm is a proper tool for optimizing all key parameters that can have mutual effects on the vibration attenuation since the vibration isolation is a non-linear problem. A genetic algorithm code is implemented with the help of Python Software and Finite Element Program (Plaxis) for all three systems and the optimized parameters for reaching 75% efficiency of the barrier are calculated. The result of the parametric study showed that the single wall system needs the lowest value of normalized depth for reaching the highest value of the efficiency. Also, the mutual study of all parameters proved that the results are very different from a single para-metric study. The comparison of all systems demonstrated that a double wall barrier is the best system for different frequencies.
ICONHIC2022 - International Conference on Natural Hazards & Infrastructure, 2022
Studies on vibration isolation have attracted the attention of researchers for the last two decad... more Studies on vibration isolation have attracted the attention of researchers for the last two decades because they can have a significant effect on the comfort of occupants of the buildings located near the source. A typical assumption for the study of ground-borne vibration is considering soil as homogeneous, which is unrealistic in many real cases. Therefore, the main focus of this study is to find the effect of soil layering on the efficiency of geofoam-filled trenches. An automated and comprehensive parametric study has been performed by coupling Plaxis, Python and Matlab programs. The results of this automated parametric study allow the identification of the main governing parameters, which are location (𝑋) and depth (𝐷) of the trench and shear wave velocities of the soil (𝑉𝑠). Results showed that a depth of 𝐷 = 1 and 1.25 𝜆𝑟, is enough to have a successful active isolation system. In addition to this, the study shows that the trench is more efficient in soils with larger values of shear wave velocity (𝑉𝑠). The use of this automated process can also assist with similar parametric studies for other applications and during design of similar installations.
The recent researchers have discovered microtremor applications for evaluation of the liquefactio... more The recent researchers have discovered microtremor applications for evaluation of the liquefaction potential. Microtremor measurement is a fast, applicable and cost-effective method with extensive applications. In the present research the liquefaction potential has been reviewed by utilization of microtremor measurement results in Babol city. By using the fundamental frequency and amplification factor, the value of vulnerability index (Kg) was calculated and the liquefaction potential has been evaluated. For controlling the accuracy of this method, its output has compared with the results of Seed and Idriss method in 30 excavated boreholes within the study area. These two methods show an acceptable conformity with each other. Also, the artificial neural network (ANN) with different inputs was trained. Regarding the results of the three methods, we can conclude the threshold value of liquefaction potential is Kg=5. By reviewing and comparing these three methods, it will be observed t...
In this study, the seismic behavior of a shallow tunnel with square cross section is investigated... more In this study, the seismic behavior of a shallow tunnel with square cross section is investigated in a two layered and elastic heterogeneous environment using numerical method. To do so, FLAC finite difference software was used. Behavioral model of the ground and tunnel structure was assumed linear elastic. Dynamic load was applied to the model for 0.2 seconds from the bottom in form of a square pulse with maximum acceleration of 1 m/s<sup>2</sup>. The interface between the two layers was considered at three different levels of crest, middle, and bottom of the tunnel. The stiffness of the two upper and lower layers was considered to be varied from 10 MPa to 1000 MPa. Deformation of cross section of the tunnel due to dynamic load propagation, as well as the values of axial force and bending moment created in the tunnel structure, were examined in the three states mentioned above. The results of analyses show that heterogeneity of the environment, its stratification, and p...
Installation of stone columns is recognized as a usual procedure for the treatment for soft clay ... more Installation of stone columns is recognized as a usual procedure for the treatment for soft clay soils. In the current research, three-dimensional finite-element analyses were performed to simulate the behavior of multilayer geosynthetic-reinforced granular bed over stone column-reinforced soft soil using the ABAQUS. An extensive research was conducted for better understanding of the mechanism of load transfer in ordinary stone columns (OSCs) and geosynthetic-encased columns (GECs) installed under a concrete foundation. Parametric studies were also carried out to investigate the effects of factors such as hardness of the geosynthetic encasement and the region replacement proportion on the overall behaviour of the GECs group. The results designated that utilizing of more than one geosynthetic reinforcement with stone columns is not so effective to reduce the maximum settlement. But, a multilayer reinforcement system is efficient to decrease the maximum settlement when stone columns are not used. It was also shown that there is a large growth in the amount of stress concentration proportion with the presence of geosynthetic reinforcement in comparison with the amount when there is no geosynthetic reinforcement present.
This article analyses the reliability based on the deterministic method and acceleration attenuat... more This article analyses the reliability based on the deterministic method and acceleration attenuation in the Chalus City, as well as, obtaining the density function of probability distribution and statistics for cyclic stress ratio (CSR). The density function of probability distribution and the cycle resistance ratio (CRR) can be concluded from the possibility of the cycle of resistance curves. The proposed first-order, second-moment procedure is used to determine the relationship between three factors including, the probability of liquefaction, the safety factor and the reliability index. In this study, the numerical approach of genetic algorithm is utilized to minimize the function of the reliability index. The usage of genetic algorithm model provides a reliable mechanism suitable for a computer program. Two empirical relationships based on P L , \( N_{\text{SPT}} \), and CSR with a correlation coefficient and mean error of 95 and 10%, respectively, and the relationship between P ...
Due to the significant delay and cost associated with experimental tests, a model based evaluatio... more Due to the significant delay and cost associated with experimental tests, a model based evaluation of concrete compressive strength is of high value, both for the purpose of strength prediction as well as the mixture optimization. In this regard, several recent studies have employed state-of-the-art regression models in order to achieve a good prediction model, employing available experimental data sets. Nevertheless, while each of the employed models can better adapt to a specific nature of the input data, the accuracy of each individual model is limited due to the sensitivity to the choice of hyperparameters and the learning strategy. In the present work, we take a further step towards improving the accuracy of the prediction model via the weighted combination of multiple regression methods. Moreover, a heuristic Genetic Algorithm (GA)-based multi-objective mixture optimization is proposed, building on the obtained multi-regression model. In particular, we present a dataaided fram...
In this study, the seismic behavior of a shallow tunnel with square cross section is investigated... more In this study, the seismic behavior of a shallow tunnel with square cross section is investigated in a two layered and elastic heterogeneous environment using numerical method. To do so, FLAC finite difference software was used. Behavioral model of the ground and tunnel structure was assumed linear elastic. Dynamic load was applied to the model for 0.2 seconds from the bottom in form of a square pulse with maximum acceleration of 1 m/s 2. The interface between the two layers was considered at three different levels of crest, middle, and bottom of the tunnel. The stiffness of the two upper and lower layers was considered to be varied from 10 MPa to 1000 MPa. Deformation of cross section of the tunnel due to dynamic load propagation, as well as the values of axial force and bending moment created in the tunnel structure, were examined in the three states mentioned above. The results of analyses show that heterogeneity of the environment, its stratification, and positioning of the inte...
Abstract In this paper, considering the plain strain conditions, a numerical study has been condu... more Abstract In this paper, considering the plain strain conditions, a numerical study has been conducted to investigate the behavior of multi layer geosynthetic-reinforced granular bed overlying a soft soil using the Fast Lagrangian Analysis of Continua (FLAC) program. The ...
Background: During an earthquake, significant damage can result due to instability of the soil in... more Background: During an earthquake, significant damage can result due to instability of the soil in the area affected<br>by internal seismic waves. Liquefaction is known as one of the major causes of ground failure due to the<br>earthquake. Various procedures have been classified for assessing liquefaction phenomenon into two main groups,<br>including the deterministic and probabilistic approaches.<br>Results: Four deterministic methods and one probabilistic approach, which is a reliability procedure are considered for<br>assessing the liquefaction potential in Babol City. The main purpose of this comprehensive research is to evaluate the<br>liquefaction potential and to determine the validation and accuracy of the reliability approach. For this purpose, 60<br>boreholes including almost 600 field records in different parts of Babol City are analyzed and liquefaction and nonliquefaction areas are identified. Microzonation maps are provided by r...
My reasons and purposes for undertaking this project When simulating an earthquake, the structure... more My reasons and purposes for undertaking this project When simulating an earthquake, the structure should not only be tested using records registering in the free field of soil. The dynamic response of a structure during an earthquake depends on the type of soil foundation. A realistic estimate of the effect of an earthquake on a structure cannot be made without this. Soil type, soil layer and changes in the depth of the layer are factors affecting the seismic behavior of structures that have been considered in the analysis of structures. It can be said that soil-structure interaction produces behavior that is closer to actual behavior. After considering a soft soil substructure, structures assumed to have a rigid connection to the soil will show softer behavior. Soil damping will increase all the damping of the system, but further review of the factors affecting the performance of a structure should be done [1]. The shift of functional design has been from the force method to design. After structural analysis and estimation of internal forces of members and deformation caused by gravity loads and lateral loads of an earthquake, the performance of structural components will be examined according to accepted criteria. In original and non-original members controlled by deformation, non-linear deformation analysis is beyond capacity. For this purpose, member deformation capacity should meet the proposed regulations by considering all simultaneous effects to a member [2]. To define the performance of a specified structure, it is necessary to identify the acceptable extent of damage of the earthquake. ATC40 and, FEMA 273 define three levels of structural performance as follows: Immediate occupancy: Structural damage after an earthquake is negligible and the vertical and lateral load-bearing structural systems maintain almost all properties existing before the earthquake. Life safety: Significant damage occurs to the structure but there is still a safety margin before considering the structure unstable. Structural and non-structural members will not fall. Structural stability or collapse prevention: Structural damage has reached the point at which the structures have not yet reached the stage of complete collapse and retain vertical stability.
My reasons and the purpose of undertaking this project The climate of an area imposes specific en... more My reasons and the purpose of undertaking this project The climate of an area imposes specific environmental conditions on it. One of the most influential circumstances in a region is its soil moisture content. Any changes in soil moisture status will effect soil conditions. When the soil is not quite saturated or is dry, these soil conditions are commonly known as " partially saturated " and " unsaturated ". Almost 40% of the natural surface soil globally is unsaturated. The soil in the vicinity of the surface layers are more influenced by climatic, physical and environmental factors and their water content will be more variable [1]. One important mechanical and physical property of soil and aggregate dependence is the level of stress and strain. Determination of the basic relationship for expression of stress-strain in soil is difficult and prediction of the behavior of all features in a model is practically impossible. Analysis and determination of the distribution of stress and strain in soil in geotechnical structures has traditionally been based on Hooke's law of elastic linear behavior. The introduction of nonlinear elastic models was a new step forward for models in the prediction of the behavior of soil. The stress-strain curve of unsaturated soil is much more complex and varied than for saturated soil and must be described properly by basic models in relation to the conditions of unsaturated soil. Environmental factors and the passage of time create a natural soil structure. Structure and soil texture play an important role in its geotechnical features. Another important parameter for determining the stress-strain behavior of soil is soil type. The soil type and higher percentages on gradation curves indicate that certain substances can change the behavior of soil. Dynamic parameters are essential to the analysis and design of geotechnical structures in nonlinear analysis under dynamic loading. It is essential to have sufficient information about the response and behavior of unsaturated soils under loading to design and build safe and economic structures. Cyclic loading on the foundations can be caused by coastal waves, wind, operating machinery, wind turbines and earthquakes. The addition of cyclic loads increases the pore pressure in the soil. In sandy soil, if the magnitude and number of cycles of loading are high and the periods of the soil and earthquakes are close, the resulting pore pressure will be equal with effective stress between the soil particles and soil shear strength will decrease with the destruction of the interaction between sand grains. A decrease in soil strength and stiffness can cause damage in whole or in part of foundation and can create a substantial mass settlement of soil. Plastic strain is a major cause of high settlement foundations under cyclic loading [2].
In regions of high seismic activity, soil liquefaction has been identified as a major hazard to b... more In regions of high seismic activity, soil liquefaction has been identified as a major hazard to buried structures. Liquefaction has been defined as the transformation of cohesion less material from a solid state into a liquefied state as a consequence of increased pore pressure and reduced effective stress. Liquefaction of a soil deposit does not necessarily mean that ground failure occurs, but when liquefaction is combined with certain geologic conditions, it can lead to large permanent ground movement and soil failure. Conditions most conducive to liquefaction involve loose cohesion less granular deposits combined with a high water table. Lateral spreading and settlement are one of the most common forms of ground deformation associated with liquefaction during earthquakes. Lateral spreading and settlement pose special problems for buried constructions in areas subject to earthquakes. For the siting and design of underground constructions like piles and pipelines in seismic regions, it is important to identify areas susceptible to liquefaction. Over the years, some of the most substantial, and costly damages to the early slopes and the foundation of structures has been due to liquefaction of sands during earthquakes; hence, it is imperative to take countermeasures against liquefaction and suggest an approach to combat it such that while the soil liquefies, the damage is minimum. 2. Aims The aim of this project is to: a) To examine the influence of various factors on the liquefaction susceptibility of sandy sites and the magnitude of associated ground deformations (settlement, lateral spreading); b) To investigate the effect of the liquefaction on buried structures (piles, pipelines); and c) To assess the effectiveness of various countermeasure techniques. 3. Research Methodology This project will be carried out in two stages so as to ensure achieving reliable and accurate results. The main focus of this project will be on Ottawa and Nevada sand as these kinds of sands are so popular in this topic. Moreover, a majority of scientists have done their research on this sand in liquefaction topic and it can give me more chance to validate the results of project with other works. In the first stage, a table model for the seismic laboratory will be constructed and tests will be run. In the second stage, upon completion of testing, the settlement of liquefaction, lateral spreading, pure water pressure and the effect of the geometry of the pipe on the capacity of the different layers of soil liquefaction potential will be evaluated through displacement. After analysing the experimental results, the laboratory model will be modelled through numerical simulation with FALC program and the model will be appraised based on input parameters. Finally, the numerical model will be estimated by comparing the experimental and numerical model. Then, diverse elements including the settlement of liquefaction, lateral spreading, pure water pressure and effect of the geometry of the pipe on the capacity of the different layers of soil liquefaction potential will be evaluated based on changing parameters by means of software numerical. In addition, there are other factors that can be assessed during testing experimental model. Parameters include: The effect of loading frequency; the effect of underground constructions materials; the effect of the thickness of underground structures; the effect of soil dilation angle; the effect of thick layer of liquefaction; the effect of diameter pipe; the effect of buried deep underground structures; the effect of damping soil; the effect of the relative density of soil; the effect of underground water level 4. Significance Small-scale modelling of a full-scale prototype offers advantages in that the model may be constructed more easily, thus saving time and money, and the model test may be conducted in a controlled environment. Demystifying the behavior of granular media by a micromechanics-based plasticity model
Granular materials are ubiquitous and important to our everyday life. They are seen in form of bo... more Granular materials are ubiquitous and important to our everyday life. They are seen in form of both natural and engineering materials, such as sand, sugar, food grains and powders in agricultural, pharmaceutical, energy and chemical industries. Indeed, granular materials are the second-most manipulated material in the industry (next to water). As a typical example of granular media, sand is important to a wide range of key infrastructures pertaining to the quality and safety of our daily life and the economy of many countries around the world. Many new infrastructures such as wind turbines, high-speed railways, tunnels, pipelines and earth dams which are lifelines to the economy of many countries will be unavoidably built on/in sand. The mechanical behavior of sand underpins the critical performance and serviceability of these structures and is the key factor to be considered in their design, construction, operation and maintenance. Due to the geological deposition process, most sands exhibit highly anisotropic fabric structures which are closely associated with preferentially orientated particles, void spaces and interparticle contacts. Fabric anisotropy has profound effect on the mechanical behavior of sand and thus influences such phenomena as embankment failure and soil liquefaction (the contact forces between sand particles are so low that the sand behaves like liquid) which can cause catastrophic hazards to both human lives and properties. If the soil is assumed isotropic, the associated geotechnical design will be either too dangerous or too conservative. For instance, back-analysis indicated that liquefaction failure of the Lower San Fernando Dam in 1971 has been due to neglecting of the fabric effect on sand liquefaction resistance in design. This project aims to develop a micromechanics-based plasticity model for sand accounting for effect of sand anisotropy and its evolution. Robust, efficient and accurate numerical technique will be developed to implement the proposed model in the finite element software package Abaqus which is widely used in geotechnical design and research. The model will then be used to do improved analysis of some challenging geotechnical problems through collaboration with industry. Engineering protocol for considering soil anisotropy in geotechnical design will then be developed based on the numerical analysis and its application in real geotechnical problems.
The pore network of granular media can be controlled by the particle shape, particle size distrib... more The pore network of granular media can be controlled by the particle shape, particle size distribution and the degree of inter-particle consolidation. Sedimentary processes, such as those observed in the formation Aeolian sandstones, can result in layered gradations and variable flow properties. Whilst particle rearrangement can be initiated by global processes (e.g. liquefaction) or localised ones (e.g. shear deformation bands). Where inter-particle attrition occurs, both the particle size distribution and the degree of consolidation can be significantly altered. This project aims to determine the process-structure-property relationships for granular media subjected to deformation processes and the resulting altered flow. Discrete Element Modelling (DEM) simulations of the deformations will be complemented by triaxial cell experimental studies combined with 3D particle imaging using X-ray Computed Tomography. The bulk fluid flow properties will be determined under confined stress conditions experimentally, and analysed at pore scale using the Lattice Boltzmann Method (LBM) for computational fluid dynamics.
1. Background When expansive clay soils are subjected to moisture, they may swell and subsequentl... more 1. Background When expansive clay soils are subjected to moisture, they may swell and subsequently their strength decreases. Therefore, presence of such clay soils with possibility of volume change due to environmental effects is known as one of the common problems in geotechnical engineering practice. Nowadays, improvement methods are widely used around the world. Application of these methods in construction improves the geotechnical parameters of the soil, reduces the incurred costs, shortens the construction time, and increases durability of the construction materials. In these methods, the reinforcing or stabilising type of materials are used to strengthen the soil and to improve the engineering characteristics and mechanical properties of the soil, namely shear strength parameters, stiffness, ductility, and load bearing capacity, using scientific principles and new technologies. With advances in soil improvement techniques, there are multiple methods of soil reinforcement and stabilization choices depending on the type of the soil and project condition including mechanical, chemical, physical, biological (growing plant), and electrical techniques. Soil reinforcement technique is considered as a physical method that was first proposed by Vidal et al. (1966) in France. One of the soil reinforcement methods is mixing it with short fibres and filaments. Combination of these reinforcing elements with soil forms a composite material that involvement of reinforcement elements with soil grains improves soil strength and ductility. Gary and al-Rifai were among the first researchers who examined the reinforced soil using triaxial compression tests on fibre reinforced sand, and they showed that the increase in soil strength is proportional to the amount of reinforcing materials. The findings of Ranjan et al (1996). on samples reinforced with fibres using triaxial tests, studies carried out by Wang and Frost using uniaxial and triaxial tests on mechanical behavior of reinforced argillaceous sands, as well as the triaxial direct shear tests conducted by Santoni and Bistro on reinforced sand soils. All studies indicate the fact that the reinforced samples have more ductility than non-reinforced ones, and the shear strength increases by increasing the amount fibres in the soil. Michalowski and Zhao (1996) proposed a measure for breaking of sand reinforced with steel and polyamide fibres based on a comprehensive experimental and theoretical research. According to their study, reinforcement increases the compressive and shear strength of the soil, improves the response of soil mass to dynamic loads, increases dynamic shear moduluse of the soil, reduces liquefaction potential, and increases the soil ductility [1]. Soleimani et al. (2016) investigated the dynamic behavior of the sand containing fibre under triaxial cyclic loading. Their study indicated that adding fibre improves shear strength and the maximum axial strain of the soil [2].
This is the list of almost all geotechnical engineering's professors throughout the world in diff... more This is the list of almost all geotechnical engineering's professors throughout the world in different universities. I spent about two years collecting this information. I hope to be practical for other Ph.D. applicants in geotechnical engineering. In this file, you can find all mandatory information related to the professors including their email address, their research interest, their telephone and the name of their university.
چاپ کتاب به زبان انگلیسی در نشریات بین المللی اروپایی
تبدیل پروژها و پایان نامه های دانشگاهی شما ... more چاپ کتاب به زبان انگلیسی در نشریات بین المللی اروپایی تبدیل پروژها و پایان نامه های دانشگاهی شما به کتاب و به زبان انگلیسی امکان نشر فیزیکی و نشر الکترونیکی کتاب توسط ناشر بین المللی تخصیص ISBN به کتاب شما توسط ناشر توزیع کتاب در سراسر دنیا ایجاد صفحه مختص به کتاب در سایت های Amazon, eBay, E-Book و دیگر مراجع نشر کتاب تخصیص بخشی از درآمد فروش کتاب به نویسنده دریافت مبلغ درآمد در داخل ایران شماره تماس: 09123773049 نقی زاده ایمیل: mehran.naghizadehrokni@rwth-aachen.de آدرس: شهرستان سیمرغ، شهر کیاکلا، خیابان بهنمیر، جنب مصالح فروشی نقی زاده
One of the devastating effects of the earthquake is on liquefaction phenomenon site, which is one... more One of the devastating effects of the earthquake is on liquefaction phenomenon site, which is one of the most important and most complex topics in seismic geotechnical engineering. Liquefaction is a phenomenon that occurs in loose, saturated sediments without stickiness in undrained conditions under the influence of waves caused by earthquakes or heavy static load. In order to cope with devastating effects of this phenomenon, it is essential to identify areas prone to liquefaction. This identification can be conducted as microzoning, in which risk capacity is determined in different areas. Thus, in this paper, the zoning map of Babol liquefaction risk will be provided. In this regard, a study was conducted on the soils in Babol and after examining different areas of the city, laboratory results and field studies of more than 50 boreholes in different areas with a depth of 20 m were analyzed for finding liquefaction and non-liquefaction segments. In this study, different approaches were used including Seed, Iwasaki, Haeri and Yasrebi, Chin & Zhang and Sewmez & Gocojlou procedures and finally, a computer program was written for examining and providing microzoning map of Babol liquefaction risk.
This study focuses on evaluating the performance of geofoam-filled trenches in mitigating ground ... more This study focuses on evaluating the performance of geofoam-filled trenches in mitigating ground vibration transmissions in both homogeneous and layered soil conditions. The research employs fully automated numerical models by integrating Plaxis software with the Python programming language. This integration enables the comprehensive evaluation of the screening effectiveness of the trenches in different soil scenarios. The study conducts a parametric analysis to identify the key governing parameters of the trench. The results highlight that the depth of the trench exhibits the most significant impact on its efficiency as a vibration barrier. Furthermore, a genetic algorithm model is presented to optimize all the parameters simultaneously, considering their mutual interactions. To enhance the prediction capabilities, artificial neural network models and a quartic polynomial equation are developed to estimate the efficiency of the trench. The comparison between the numerical modeling results and the predictions from the developed models demonstrates their accuracy in estimating the trench's efficiency. Additionally, an application is developed to facilitate the utilization and sharing of the developed models and data. Users can easily install and access the application, which provides convenient access to data, predicts the efficiency of the trench, and enables the optimization of the governing parameters.
This study presents the performance of geofoam-filled trenches in mitigating ground vibration tra... more This study presents the performance of geofoam-filled trenches in mitigating ground vibration transmissions by the means of a comprehensive parametric study. Fully automated 2D and 3D numerical models are applied to evaluate the screening effectiveness of the trenches in the near field and far field schemes. The validated model is used to investigate the influence of geometrical and dimensional features on the trench with three different configurations including single, double, and triangular wall obstacles. The parametric study is based on complete automation of the model through coupling finite element analysis software (Plaxis) and Python programming language to control input, change the parameters, as well as to produce output and calculate the efficiency of the barrier. The main assumption during the parametric study is treating each parameter as an independent variable and keeping other parameters constant.
An optimization model is also presented to optimize the governing factors of geofoam or concrete-filled trenches as a wave barrier. A genetic algorithm code is implemented with coupling the Python software and the finite element program (Plaxis) for optimization of all parameters mutually. Furthermore, three different configurations including single, double, and triangular wall systems are evaluated with the same cross-sectional area for considering the effect of the shape of the barrier in attenuating the incoming waves.
A usual assumption for the study of ground-borne vibration is considering soil as homogeneous, which is unrealistic. Therefore, it is necessary to find the effect of non-homogeneity of the soil on the efficiency of the geofoam-filled trench. A comprehensive parametric study has been performed automatically by coupling Plaxis and Python under the assumption of treating each parameter as an independent variable. The results showed that some parameters have a considerable impact on each other.
Therefore, the interaction of all governing parameters on each other is also evaluated through the response surface methodology method. In addition, a genetic algorithm code is presented for optimizing all parameters mutually in homogeneous and layered soil. The results showed that layered soil requires a deeper trench for reaching the same value of the efficiency as in homogeneous soil. An artificial neural network model and a quartic polynomial equation are developed in order to estimate the efficiency of the geofoam-filled barrier. The agreement between the results of numerical modelling and the developed models demonstrated the capability of the models in predicting the efficiency of the geofoam-filled trench.
Finally, an application has been developed to easily use and share all developed models and data. The user can install and use the app to access all data, predicting the efficiency of the trench and optimizing the governing parameters.
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تبدیل پروژها و پایان نامه های دانشگاهی شما به کتاب و به زبان انگلیسی
امکان نشر فیزیکی و نشر الکترونیکی کتاب توسط ناشر بین المللی
تخصیص ISBN به کتاب شما توسط ناشر
توزیع کتاب در سراسر دنیا
ایجاد صفحه مختص به کتاب در سایت های Amazon, eBay, E-Book و دیگر مراجع نشر کتاب
تخصیص بخشی از درآمد فروش کتاب به نویسنده
دریافت مبلغ درآمد در داخل ایران
شماره تماس: 09123773049 نقی زاده
ایمیل: mehran.naghizadehrokni@rwth-aachen.de
آدرس: شهرستان سیمرغ، شهر کیاکلا، خیابان بهنمیر، جنب مصالح فروشی نقی زاده
The study conducts a parametric analysis to identify the key governing parameters of the trench. The results highlight that the depth of the trench exhibits the most significant impact on its efficiency as a vibration barrier. Furthermore, a genetic algorithm model is presented to optimize all the parameters simultaneously, considering their mutual interactions.
To enhance the prediction capabilities, artificial neural network models and a quartic polynomial equation are developed to estimate the efficiency of the trench. The comparison between the numerical modeling results and the predictions from the developed models demonstrates their accuracy in estimating the trench's efficiency.
Additionally, an application is developed to facilitate the utilization and sharing of the developed models and data. Users can easily install and access the application, which provides convenient access to data, predicts the efficiency of the trench, and enables the optimization of the governing parameters.
An optimization model is also presented to optimize the governing factors of geofoam or concrete-filled trenches as a wave barrier. A genetic algorithm code is implemented with coupling the Python software and the finite element program (Plaxis) for optimization of all parameters mutually. Furthermore, three different configurations including single, double, and triangular wall systems are evaluated with the same cross-sectional area for considering the effect of the shape of the barrier in attenuating the incoming waves.
A usual assumption for the study of ground-borne vibration is considering soil as homogeneous, which is unrealistic. Therefore, it is necessary to find the effect of non-homogeneity of the soil on the efficiency of the geofoam-filled trench. A comprehensive parametric study has been performed automatically by coupling Plaxis and Python under the assumption of treating each parameter as an independent variable. The results showed that some parameters have a considerable impact on each other.
Therefore, the interaction of all governing parameters on each other is also evaluated through the response surface methodology method. In addition, a genetic algorithm code is presented for optimizing all parameters mutually in homogeneous and layered soil. The results showed that layered soil requires a deeper trench for reaching the same value of the efficiency as in homogeneous soil. An artificial neural network model and a quartic polynomial equation are developed in order to estimate the efficiency of the geofoam-filled barrier. The agreement between the results of numerical modelling and the developed models demonstrated the capability
of the models in predicting the efficiency of the geofoam-filled trench.
Finally, an application has been developed to easily use and share all developed models and data. The user can install and use the app to access all data, predicting the efficiency of the trench and optimizing the governing parameters.