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1 - Design Approach of Bolts and Sandwiching Steel Plates in Hybrid-Sandwiching Systems Based on FEM
Alireza Zaferani Pasha Javadi Parham Memarzadehشماره 1 , دوره 13 , بهار 1402Conventional reduced beam sections (RBS) maintain their capacity with up to 4% drift angle, after which local buckling at the reduced section significantly reduces their resistance. The use of hybrid-sandwiched reduced beam sections (HS-RBS) in the reduced section of co چکیده کاملConventional reduced beam sections (RBS) maintain their capacity with up to 4% drift angle, after which local buckling at the reduced section significantly reduces their resistance. The use of hybrid-sandwiched reduced beam sections (HS-RBS) in the reduced section of conventional RBS beams previously proposed by the authors can increase the energy absorption capacity, allowing the beam to reach 7% drift without losing capacity. The experimental results indicate that placing the HS-RBS in the reduced section of the RBS beam does not disrupt its main role in forming a plastic joint in the reduced section. HS-RBS is comprised of grout, nuts and bolts, and the sandwiching plates. In this system, the bolts and the sandwiching plate enclose the grout and the bolts are placed in the grout on two sides of the beam web in the reduced section to increase the grout's capacity to resist the tensile stresses arising from the web buckling. The sandwiching plate is located in the reduced section on two sides of the flange to enclose the grout and increase the buckling resistance of the flange. This study employed finite element modeling (FEM) to analyse beam bolts with different diameters for different sections of the HS-RBS to obtain the best diameter for each bolt. Moreover, sandwiching plates with different thicknesses were examined to find the best thickness. پرونده مقاله -
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2 - Seismic Fragility Analysis of a RC Bridge with Uniform and Non-Uniform Random Scour Patterns
Ali Raoof Mehrpour Hosseini Mehran Seyedrazzaghi Nasser Shamskiaشماره 1 , دوره 13 , بهار 1402Previous natural disaster assessments had identified bridges as vulnerable structures against hydraulic hazards, particularly scouring. Additionally, in areas with high seismic activity, bridges are exposed to minor damage to complete collapse, in most cases requiring i چکیده کاملPrevious natural disaster assessments had identified bridges as vulnerable structures against hydraulic hazards, particularly scouring. Additionally, in areas with high seismic activity, bridges are exposed to minor damage to complete collapse, in most cases requiring immediate occupancy structural performance levels in the event of an earthquake. Previous studies have focused on vulnerability assessments by considering the effects of simultaneous hazards. This study examines a simply supported RC bridge model with a discontinuous deck-girder superstructure installed on cap beams via elastomers. Seismic vulnerability assessments were conducted by developing fragility curves through nonlinear time history analyses on scoured models. One of the study's objectives is to consider the effects of non-uniform patterns in different foundations of the four-span model by generating random depth samples. The study also evaluated even depths as the uniform scenario for vulnerability assessment. The results indicate that, in all limit states considered in the study, the uniform has a higher probability of exceeding the limit states than the non-uniform scenario. However, in evaluating critical scoured models, the uniformly maximum credible scoured pattern did not necessarily have a higher probability of exceeding all limit states. In other words, the non-uniform scenario, which had pier(s) with the maximum credible scour depth, had a more critical vulnerability in some limit states. پرونده مقاله -
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3 - Multi-Objective Optimization of the Depth and Cementation of Liquefiable Soil Surrounding Tunnels
Mohammad Shabani Soltan Moradi Mohammad Azadi Homayoun Jahanianشماره 1 , دوره 13 , بهار 1402Designing tunnels in liquefiable sandy soils presents a significant challenge in determining the optimal depth and extent of soil cementation around them. Reducing the depth of the tunnel decreases both the bending anchor force and the axial load on the tunnel's shell, چکیده کاملDesigning tunnels in liquefiable sandy soils presents a significant challenge in determining the optimal depth and extent of soil cementation around them. Reducing the depth of the tunnel decreases both the bending anchor force and the axial load on the tunnel's shell, yet it leads to an increase in ground surface settlement, and the opposite is true when depth is increased. Enhancing the cementation level at the tunnel's optimal depth reduces both structural uplift and shear forces exerted on the tunnel lining, but it also leads to an increase in axial loads and vice versa. Given the contradictory nature of these outcomes, the FLAC software was employed to simulate tunnels in liquefiable soils to address this dilemma. Subsequently, a neural network was utilized to identify correlations between the inputs and outputs of the simulation. This network was the objective function for identifying optimal values by applying a genetic algorithm. Optimal design parameters were derived using the NSGA-II modified algorithm, a multi-objective optimization technique based on the objective functions. Ultimately, Pareto charts generated from the multi-objective optimization process enabled designers to select the most suitable tunnel location according to their specific requirements concerning depth and soil cementation in liquefied soils. پرونده مقاله -
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4 - Optimization of surficial settlement originated from the excavation of twin tunnels on surface structures with finite dimensions
Hesam Pourhabiby Masulehشماره 1 , دوره 13 , بهار 1402In urban regions, the stability and safety of surface structures are essential. With the development of cities and increasing building density in metropolitan areas, the construction of underground structures like subway tunnels will be considered more and more. The tun چکیده کاملIn urban regions, the stability and safety of surface structures are essential. With the development of cities and increasing building density in metropolitan areas, the construction of underground structures like subway tunnels will be considered more and more. The tunnels are located close to the ground surface in most urban regions. Therefore, excavating these tunnels causes some displacements in the soils around the tunnels, leading to some adverse effects on the surface structures. Predicting deformations looks essential to reducing these effects, showing the importance of tunnel and structure interaction. In this paper, using three-dimensional numerical simulation and parametric studies, the effect of various parameters on the displacement of tunnels and their adjacent buildings are studied. The optimum surface settlement values are predicted using the neural network and developed optimization algorithms. The parameters under study are composed of: the horizontal distance between tunnels, the depth of tunnels, the angle between tunnels, the excavation distance between two tunnels, the diameter of the tunnels, tunnels' contraction, the soil's internal friction angle, and the soil's cohesion. Using a neural network and optimization algorithms can considerably help optimize the design and significantly reduce adverse effects on the surface structures during the tunnel excavation. The results from the neural network showed that the optimum state of displacement happens when the soil's cohesion, tunnels' contraction, diameter, and depth are the minimum values, and the excavation distance between two tunnels is the maximum value. پرونده مقاله -
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5 - Effect of Pile Cap Geometry on Soil Arching Behavior in GRPS Embankments: A Comparative Study
mohammad amir mirzaei Monireh Karimian Mobarakeh Arif Khan Adriko norman burua rashid hajivand dastgerdiشماره 1 , دوره 13 , بهار 1402This comprehensive study in geotechnical engineering presents valuable insights and advancements in the field of Geosynthetic-Reinforced Pile-Supported Embankments (GRPS). The study focuses on the analysis of pile caps in GRPS using three-dimensional finite element mode چکیده کاملThis comprehensive study in geotechnical engineering presents valuable insights and advancements in the field of Geosynthetic-Reinforced Pile-Supported Embankments (GRPS). The study focuses on the analysis of pile caps in GRPS using three-dimensional finite element modeling, specifically employing PLAXIS-3D software. The research investigates the effects of different pile head shapes on soil arching, settlement, and stress distribution, emphasizing the significance of pile head selection for enhancing soil arching and reducing ground settlement. The study recommends larger pile heads with flattened top surfaces, as demonstrated in sections 4 and 5, as optimal choices for pile head design in GRPS projects. The proposed analytical model captures the time-dependent settlement behavior of subsoils, but a slight underestimation of settlement after embankment construction suggests the need for further consideration of factors like pile settlement and bottom sandy silt settlement. Future research should refine the analytical model to improve settlement predictions by incorporating these factors. Additionally, the study highlights the importance of investigating GRPS embankments with floating piles, complex construction processes, water effects on soil arching, and embankment performance. It is noted that earthquake loading was not specifically addressed, indicating the need for comprehensive research in this area. Overall, this study contributes to the knowledge of GRPS embankments and provides recommendations for design, construction, and future research directions. پرونده مقاله -
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6 - Location of municipal landfills Analytical Hierarchy process (AHP) In GIS environment (Case study of Qazvin city)
Mojtaba Ebrahim beiki keshmarziشماره 1 , دوره 13 , بهار 1402Solid waste is an integral part of human life and the production of its types in different quantities and qualities is one of the most important environmental problems of the present age. To prevent environmental pollution in the community, waste must be disposed of hyg چکیده کاملSolid waste is an integral part of human life and the production of its types in different quantities and qualities is one of the most important environmental problems of the present age. To prevent environmental pollution in the community, waste must be disposed of hygienically and engineeringly. One of the methods of waste disposal is engineering waste disposal method. In this study, our emphasis is on the impact of ecological factors on the location of urban solid waste landfills in Qazvin city using spatial analysis in GIS environment for optimal location of municipal landfills. For this purpose, the required digital data was collected and then transferred to the ArcGIS environment. After creating the database, multi-criteria analytical decision-making models were implemented, the reliable method of AHP hierarchical analysis. As a result, by using the AHP method, hierarchical criteria have been used to locate a suitable sanitary place for landfilling of generated waste in Qazon city, and the most optimal place has been selected from 4 proposed places for sanitary landfilling of waste. پرونده مقاله
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1 - Numerical Parametric study of Geosynthetic-Gabion Walls under Different Surcharge Loads
Mahmoud Khalatbari Abolfazl Rezaeipour Rashid Hajivand Dastgerdi Mehran Ghannad Sahand Shokriشماره 2 , دوره 12 , پاییز 1401The finite element procedures are extremely useful in gaining insights into the behavior of reinforced soil retaining walls. In this study, a validated finite element procedure was used with Abaqus for conducting a series of parametric studies on the performance of gabi چکیده کاملThe finite element procedures are extremely useful in gaining insights into the behavior of reinforced soil retaining walls. In this study, a validated finite element procedure was used with Abaqus for conducting a series of parametric studies on the performance of gabion facing wall with 2m vertical spacing Geo-grid under different surcharge loadings. The performance of the wall was presented with facing horizontal deformation along wall height, and compare to centrifuge model and field measurements. The soil properties include density, Young modulus, Poisson’s ratio, and internal friction angle were among major variables of investigation. At low loading conditions, the impact of increasing density has a significantly greater effect on the deformation of the wall compared to high loads. As the loading increases, the effect of reducing the Young’s modulus on deformations decreases. Moreover, with increasing loading, the effect of deformations due to the decrease in internal friction angle increases, but the rate of this increase decreases. The influence of Poisson’s ratio on the deformation of the walls has decreased with increasing of loading. The results show that by the increase in load, even at a shallow depth, the applied stresses on the soil increase, leading to greater deformation of the soil above the wall, and the maximum magnitude is created at a higher elevation. پرونده مقاله -
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2 - A Parametric Study of Interactions Between Liquefaction Sand Lenses and Shallow Tunnels Under Earthquake Loads
Mohammad Shabani Soltan Moradi Mohammad Azadi Homayoon Jahanianشماره 2 , دوره 12 , پاییز 1401If the saturated sand lenses are placed around the tunnels under the force of the earthquake, liquefaction will occur in them. This will cause settlement of the ground surface and changes in forces and anchors on the tunnel lining. For this purpose, it is important to e چکیده کاملIf the saturated sand lenses are placed around the tunnels under the force of the earthquake, liquefaction will occur in them. This will cause settlement of the ground surface and changes in forces and anchors on the tunnel lining. For this purpose, it is important to evaluate the change of different parameters of the sand lens and the change of the thickness of the tunnel lining in the part of the sand lens and the changes in the diameter and depth of the tunnel as well as the location of the sand lens considering the tunnel inside it. Therefore, this article investigates the mentioned changes in shallow tunnels in the location of sand lens in flowing soils surrounded by clay. In this article, FLAC 3D software is used to determine changes in pore water pressure and effective stress reduction after sand lens liquefaction. Based on the obtained results, if the sand lenses are placed at a depth of less than 10 meters, they increase the land surface subsidence by 36% compared to the reference model B, with an increase of 2 meters in the depth of the sand lens compared to the reference model B, the value of the maximum bending anchor and axial force on the tunnel lining increases by 35.7% and 14.4%, respectively, in the sand lens part. The findings of the present study can be very useful in the decision-making process of tunnels that are dug inside flowing sand lenses. پرونده مقاله -
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3 - Numerical Simulation of the Segmental Tunnels Performance in the Swelling Rocks
Arash Jeddi Rouzbeh Dabiriشماره 2 , دوره 12 , پاییز 1401In this research, the performance of tunnels with segmental lining in swelling rocks have been studied. In this regard, the way segments are arranged in relation to each other, how the segments are connected along the longitudinal and circumferential lines of the tunnel چکیده کاملIn this research, the performance of tunnels with segmental lining in swelling rocks have been studied. In this regard, the way segments are arranged in relation to each other, how the segments are connected along the longitudinal and circumferential lines of the tunnel, and the extent of creating the excavation wall, the effect of the thickness of the segment and the lining system, the effect of the depth of the tunnel and other details are studied. In this regard from the FLAC 3D software was used for numerical modeling. Among the important results obtained in this research, the displacements of the tunnel after applying the boundary conditions and modeling the segments and taking into account all the elements and the phenomenon of creep and surrounding stones with accurate values as the average initial displacement around the tunnel at the specified points are 4.63 mm, this displacement continues the upward trend with a steep slope for a week and increases up to 6.49 mm, and after a week, the increasing rhythm decreases and reaches 6.92 on average in 50 days, and this trend increases again. After 400 days, it reached the value of 9.85 and then the increasing rhythm decreased again, so that after 11 years, the average displacement reaches the value of 11.09, and after this period of time, the displacement of the tunnel becomes very insignificant. پرونده مقاله -
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4 - Modeling of Accumulated Energy Ratio (AER) for Estimating LiqueFaction Potential Using Artificial Neural Network (ANN) and Gene Expression Programming (GEP) (using data from Tabriz)
Armin Sahebkaram Alamdari Rouzbeh Dabiri Rasoul Jani Fariba Behrouz Sarandشماره 2 , دوره 11 , پاییز 1400Presenting a model specific to the city of Tabriz to estimate the liquefaction potential due to the region's seismicity and the high groundwater level can be effective in dealing with and predicting solutions to deal with this phenomenon. In recent years, the accumulati چکیده کاملPresenting a model specific to the city of Tabriz to estimate the liquefaction potential due to the region's seismicity and the high groundwater level can be effective in dealing with and predicting solutions to deal with this phenomenon. In recent years, the accumulation energy ratio (AER) as a parameter for estimating the liquefaction potential in the energy-based method proposed by Kokusho (2013) has been considered by many researchers. In this research, using perceptron multilayer (MLP) and radial base function (RBF) methods in artificial neural network (ANN) and genetic expression programming (GEP), the accumulation energy ratio using seismic and geotechnical data is modeled for the city of Tabriz. These modeling’s performed by all three methods are well consistent with the outputs. Still, the modeling performed using the Perceptron Multilayer (MLP) method is very compatible with the outputs and can estimate the results with an acceptable percentage. The relationship presented by genetic expression programming (GEP), which is trained with local data, can also yield satisfactory results from estimating the rate of accumulated energy in the study area and provided an independent and accessible relationship trained. With data specific to the study area, there is another advantage. پرونده مقاله -
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5 - Mechanical Properties of Low Strength Concrete Incorporating Carbon Nanotubes
Meysam Morsali Reza Farokhzadشماره 1 , دوره 11 , بهار 1400Nowadays, due to the increasing population and the expansion of urbanization, and consequently the need for high-rise and multi-storey buildings that , the safety and resistance of the load bearing members of the structures has become of interest to researchers. For thi چکیده کاملNowadays, due to the increasing population and the expansion of urbanization, and consequently the need for high-rise and multi-storey buildings that , the safety and resistance of the load bearing members of the structures has become of interest to researchers. For this purpose, different approaches have been proposed, including nanomaterials as a suitable and optimal method. Using nanomaterials as a percentage of cement weight improves concrete performance and increases its strength. Since these materials should be used at the beginning of concrete construction, therefore, they cannot be used in constructed structures. But a protective coating containing these nanomaterials can enhance and improve the performance of the structures, which is applicable to the fabricated structures. The purpose of this study was to investigate the effect of protective coatings with Nano silica, carbon nanotube and graphene nanomaterials. For this purpose, four thicknesses different and 2% nanomaterials different, the effect of thickness and percentage of nanomaterials were investigated. The results show that the sample containing 15% of silica with 26.74 N/mm2 has the highest effect compared to other nanomaterials. However, due to the low percentages of carbon nanotube and graphene, these materials have a significant effect. پرونده مقاله -
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6 - Stress Analysis of the Scoliosis Disorder.
Fatemeh Nori Seyed Hooman Ghasemiشماره 1 , دوره 11 , بهار 1400Scoliosis is a spine irregular deviation, which known an idiopathic ailment among children and adolescents. Indeed, applyingloads on the human spine and the capacity of the vertebral column should be tretated as random variables. The main gola of thisstudy is to compare چکیده کاملScoliosis is a spine irregular deviation, which known an idiopathic ailment among children and adolescents. Indeed, applyingloads on the human spine and the capacity of the vertebral column should be tretated as random variables. The main gola of thisstudy is to compare the maximum stress caused by weight load of a norm al and scoliosis spinal. To do so, the numerical analyses associated with the inherent random parameters of bones and applied load are performed. Accordingly, the maximum stress for all vertebrae and discs are computed. The maximum stress intensity in the cortical tissue, cancellous tissue and discs was identified. The location of the maximum stresses quantify which vertebrae and discs may get damaged and needed reinforcement and this can provide a model for predicting the location of spinal cord injury. پرونده مقاله -
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7 - Conceptual Analysis and Design and Experimental Construction of a Portable Emergency Relief Bridge
Ehsan Soltani Shahrokh Rezaeiشماره 2 , دوره 12 , پاییز 1401For a long time, our country has faced natural disasters. In recent years, it has imposed various levels of damages on the country, including those caused by wars (military maneuvers) and natural disasters (earthquakes such as Rudbar Manjil, Bam, and Azgeleh), and flood چکیده کاملFor a long time, our country has faced natural disasters. In recent years, it has imposed various levels of damages on the country, including those caused by wars (military maneuvers) and natural disasters (earthquakes such as Rudbar Manjil, Bam, and Azgeleh), and floods in cities and regions). Every year, severe floods, hurricanes, explosions, and terrorist attacks cause great suffering for millions worldwide. In a disaster, whether natural or humanitarian, it is vital to provide immediate help to those affected, but relief can often be severely interrupted, significantly if the infrastructure is damaged and the transport network is disrupted. Here, the bridge will be constructed from nonidentical prefabricated elements based on modularity. Construction of modules and final assembly is done off-site (in a factory). Because it can be deployed on-site, it transported the completed bridge in a compact form. SAP2000 software evaluated an emergency bridge's seismic design and performance using nonlinear static and dynamic analysis to save lives in the shortest amount of time, cost, construction, and installation, while also considering the structure's performance. Also, its portability is the goal of this structure. In this system, space structures were used to design the project, absorbing much energy outside their elastic range and was innovative. As a result, the ultimate bearing capacity of the space trusses will depend on the structure's geometry, the position of the supports, and the displacement load response of each member. پرونده مقاله -
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8 - Seismic Fragility Analysis of RC Continuous Girder Bridges Using Artificial Neural Network
Alireza Yazdankhah Araliya Mosleh Fatemeh Pouran Manjily Mehran Seyedrazzaghiشماره 1 , دوره 12 , بهار 1401This research aims to develop seismic fragility curves for small- and medium-sized concrete bridges. Fragility curves were generated as a function of the probability of reaching or exceeding a specific limit state in terms of the peak ground acceleration (PGA) and accel چکیده کاملThis research aims to develop seismic fragility curves for small- and medium-sized concrete bridges. Fragility curves were generated as a function of the probability of reaching or exceeding a specific limit state in terms of the peak ground acceleration (PGA) and acceleration spectral intensity (ASI). To this end, a hybrid dataset of the seismic performances of bridges was prepared by combining the results of numerical analyses and neural predictions. Three-dimensional finite-element models for 1032 bridge-earthquake cases were created, considering the nonlinear behavior of critical bridge components. In addition, multilayer perceptron (MLP) neural networks were employed to simulate artificial earthquake-bridge performance scenarios. The yield stress of reinforcing bars (Fy), the bridge height (H) as well as PGA and ASI, were considered as the input vectors of the artificial neural networks (ANN). The results of this study revealed that MLP neural networks are capable of simulating the seismic performances of bridges appropriately. It was also shown that providing a hybrid dataset of numerical results and neural predictions could lead to the fragility curves of higher correlation coefficients. The results also presented that the PGA-based fragility curves had better correlation coefficients comparing to ASI-based ones. پرونده مقاله -
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9 - Equivalent Viscous Damping in Steel Structures Equipped with Dampers.
Seyed Behdad Alehojjat Omid Bahar Masood Yakhchalianشماره 2 , دوره 11 , پاییز 1400Determination of equivalent viscous damping (EVD) is an important step in the direct displacement-based design (DDBD) method. This study aims to investigate whether the proposed method used in the equivalent lateral force (ELF) procedure, according to ASCE/SEI 7, for th چکیده کاملDetermination of equivalent viscous damping (EVD) is an important step in the direct displacement-based design (DDBD) method. This study aims to investigate whether the proposed method used in the equivalent lateral force (ELF) procedure, according to ASCE/SEI 7, for the calculation of effective damping in steel structures equipped with fluid viscous dampers (FVDs) can be used in the DDBD method. In order to evaluate the accuracy of this method, modified Jacobsen’s method and the approach used in Pennucci et al.’s study are applied to determine the EVD. At first, a set of steel structures with different heights and bays are designed for 0.75, 0.85 and 1.0 of the design base shears based on the primary calculation of the ELF procedure and then nonlinear time history analyses are carried out to determine the dampers constants and the EVD at two seismic hazard levels, i.e., design earthquake (DE) and maximum considered earthquake (MCE). According to the obtained results for the EVD, it is found that the obtained results in the ELF procedure has acceptably matched with Pennucci et al.’s approach. On the other hand, there are some differences between the obtained results and those obtained from modified Jacobsen’s method. Therefore, the ELF proposed equation for calculating EVD can be used in the DDBD method in mid-rise steel structures equipped with FVDs to accurately determine the EVD. پرونده مقاله -
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10 - The Necessity of Integrating Soil Treatment Systems in BIM from Design to Final Construction
Mohammad Pardsouie Mehdi Mokhberi Seyed Mohammad Ali Zomorodian Mohammad Pardsouieشماره 2 , دوره 12 , پاییز 1401In projects that involve surcharge and prefabricated vertical drains (PVDs) systems for the treatment of weak underlying layers, embankment failures, tension cracks, and differential settlements, surficial heaves, and foundation failures were addressed in various litera چکیده کاملIn projects that involve surcharge and prefabricated vertical drains (PVDs) systems for the treatment of weak underlying layers, embankment failures, tension cracks, and differential settlements, surficial heaves, and foundation failures were addressed in various literature. Overestimation and unrealistic design assumptions made by geotechnical and structural engineers are the main reasons for most of the cases. In all these cases a simple collaboration between different parties in the project ranging from designers to field engineers could have decreased or prevented these undesirable outcomes. The problem of neglecting the infiltration of the embankment in the ground as a new distinct layer with all the necessary requirements, and also disturbance caused as a result of PVDs installation in four cases: preloading case, fill removal, main structure construction, and post- construction phase are discussed. A few design recommendations are given regarding the stated issues. Since after the completion of soil treatment operations, the soil engineering parameters and in some cases even soil stratification had changed, care should be taken to use the new treated parameters in the final design process, not the preliminary site report parameters. Neglecting this issue may lead to severe malfunctions and even unpredictable failures. BIM technology has the possibility of integrating all aspects, and complexities of geotechnical engineering in the structural-architectural platform as a whole, which would revolutionize the construction industry. Till now only the structural-architectural part is done and further research and investment are necessary for the geotechnical aspect. پرونده مقاله
