Sharif University of Technology Sharif Journal of Civil Engineering 2676-4768 41 2 2025 09 22 Experimental Study of the Yield Surface of Saturated Silty Tailings Experimental Study of the Yield Surface of Saturated Silty Tailings 1 12 23605 10.24200/j30.2024.64136.3306 FA Amir Abbas Riahi Khoo Department of Civil Engineering, Ferdowsi University of Mashhad Ali Akhtarpour Department of Civil Engineering, Ferdowsi University of Mashhad 0000-0003-1654-0194 Journal Article 2024 03 05 Static liquefaction is one of the most important challenges for the stability of mining tailings dams. Several experimental studies have been conducted on this issue within the framework of critical state theory. Additionally, deformations such as tensile cracks and unusual static deformations of these dams are among the other issues related to the stability of these structures. Numerical simulation of the stress-strain behavior of materials under various loading conditions requires a suitable constitutive model, with one of its main components being the yield criterion. Extensive studies have been conducted to identify the yield surfaces of soil materials (sand and clay) through laboratory tests, but the identification of yield surfaces for tailing materials has received less attention. This study aims to identify the yield surface of silty tailing materials from the Sungun copper mine using laboratory experiments under initial isotropic stress and saturated conditions. For this purpose, all specimens with a similar stress history were initially consolidated under isotropic stress conditions and then unloaded up to 50% of the initial confining stress. The over-consolidation ratio (OCR) of these specimens was approximately set to be two. Subsequently, the specimens were subjected to stress-controlled radial stresses in the effective mean stress-deviatoric stress (ṕ-q) space. The compatibility of the laboratory yield surface with the proposed yield surfaces of the Mroz constitutive model was examined. The results indicate that the obtained yield surface under existing stress conditions follows the non-associated flow rule. The proposed yield surface of the Mroz constitutive model, by considering appropriate constants, shows satisfactory agreement with the laboratory yield surface. The work input for each stress path demonstrates that at approximately 0.25 kJ/m2, the specimens reached yield conditions. The flow vector plots indicate that the obtained yield surface follows the non-associated flow rule. Observing linear trends in the deformation changes of the specimens after the yield point indicates rapid cementation in these materials. Static liquefaction is one of the most important challenges for the stability of mining tailings dams. Several experimental studies have been conducted on this issue within the framework of critical state theory. Additionally, deformations such as tensile cracks and unusual static deformations of these dams are among the other issues related to the stability of these structures. Numerical simulation of the stress-strain behavior of materials under various loading conditions requires a suitable constitutive model, with one of its main components being the yield criterion. Extensive studies have been conducted to identify the yield surfaces of soil materials (sand and clay) through laboratory tests, but the identification of yield surfaces for tailing materials has received less attention. This study aims to identify the yield surface of silty tailing materials from the Sungun copper mine using laboratory experiments under initial isotropic stress and saturated conditions. For this purpose, all specimens with a similar stress history were initially consolidated under isotropic stress conditions and then unloaded up to 50% of the initial confining stress. The over-consolidation ratio (OCR) of these specimens was approximately set to be two. Subsequently, the specimens were subjected to stress-controlled radial stresses in the effective mean stress-deviatoric stress (ṕ-q) space. The compatibility of the laboratory yield surface with the proposed yield surfaces of the Mroz constitutive model was examined. The results indicate that the obtained yield surface under existing stress conditions follows the non-associated flow rule. The proposed yield surface of the Mroz constitutive model, by considering appropriate constants, shows satisfactory agreement with the laboratory yield surface. The work input for each stress path demonstrates that at approximately 0.25 kJ/m2, the specimens reached yield conditions. The flow vector plots indicate that the obtained yield surface follows the non-associated flow rule. Observing linear trends in the deformation changes of the specimens after the yield point indicates rapid cementation in these materials.

https://sjce.journals.sharif.edu/article_23605_1e7281e2bfcaf5294ebeb7b4b8b60b27.pdf

Sharif University of Technology Sharif Journal of Civil Engineering 2676-4768 41 2 2025 09 22 Analysis of Plane Multi-Span Frames with the Analytical Method of Force-Displacement Combination Analysis of Plane Multi-Span Frames with the Analytical Method of Force-Displacement Combination 13 27 23612 10.24200/j30.2024.64303.3318 FA Amirhosein Bahreini Faculty of Engineering and Technology, University of Mazandaran, Mazandaran, Iran. Ali Asgari Faculty of Engineering and Technology, University of Mazandaran, Mazandaran, Iran. 0000-0002-2359-8696 Alireza Khabiri Faculty of Engineering and Technology, University of Mazandaran, Mazandaran, Iran. Reza Taghipour Faculty of Engineering and Technology, University of Mazandaran, Mazandaran, Iran. Journal Article 2024 04 08 This paper investigates the effectiveness of the mixed forced-displacement method for solving indeterminate plane frames that combine force and displacement relations based on the beam’s axial and bending deformation behavior simultaneously. In this method, the differential equations of all structural members are determined based on the general theory of the Bernoulli beam by considering the axial effects. In the following, with the help of an analytical solution and application of boundary conditions, the integral constants of the equations related to the uniaxial frames of the structure are obtained. For the effectiveness of the proposed method, three examples of common frames have been analyzed and validated with the finite element method. The results show that the answers determined by the two methods are completely consistent. One of the advantages of the combined displacement-force method is determining the parametric solution as well as the high accuracy of this method. In addition, it does not need post-processing to find the quantity of kinematic and static responses. Therefore, this method can be used as an alternative approach to the finite element method in solving multi-axial plane frames. Moreover, its capability to handle intricate loading and various boundary condition configurations highlights the method's efficiency. Furthermore, the method simplifies the simultaneous influences of material and geometric nonlinearities in the analysis process. Material nonlinearities, such as yielding and hardening, are accommodated by adjusting the stiffness matrix. In contrast, geometric nonlinearities arising from significant displacements are addressed through iterative updates of the displacement field until convergence is achieved. In summary, the mixed displacement-force method is a comprehensive and efficient tool for 2D frame analysis. The ability to provide accurate results without the need for complex numerical simulations increases the importance of this method in the range of structural analysis techniques. Future research efforts could examine developing the process to three-dimensional frames and investigating its application in the performance-based design and analysis areas. This paper investigates the effectiveness of the mixed forced-displacement method for solving indeterminate plane frames that combine force and displacement relations based on the beam’s axial and bending deformation behavior simultaneously. In this method, the differential equations of all structural members are determined based on the general theory of the Bernoulli beam by considering the axial effects. In the following, with the help of an analytical solution and application of boundary conditions, the integral constants of the equations related to the uniaxial frames of the structure are obtained. For the effectiveness of the proposed method, three examples of common frames have been analyzed and validated with the finite element method. The results show that the answers determined by the two methods are completely consistent. One of the advantages of the combined displacement-force method is determining the parametric solution as well as the high accuracy of this method. In addition, it does not need post-processing to find the quantity of kinematic and static responses. Therefore, this method can be used as an alternative approach to the finite element method in solving multi-axial plane frames. Moreover, its capability to handle intricate loading and various boundary condition configurations highlights the method's efficiency. Furthermore, the method simplifies the simultaneous influences of material and geometric nonlinearities in the analysis process. Material nonlinearities, such as yielding and hardening, are accommodated by adjusting the stiffness matrix. In contrast, geometric nonlinearities arising from significant displacements are addressed through iterative updates of the displacement field until convergence is achieved. In summary, the mixed displacement-force method is a comprehensive and efficient tool for 2D frame analysis. The ability to provide accurate results without the need for complex numerical simulations increases the importance of this method in the range of structural analysis techniques. Future research efforts could examine developing the process to three-dimensional frames and investigating its application in the performance-based design and analysis areas.

https://sjce.journals.sharif.edu/article_23612_e7b966126309c9707f07563d62d14f0c.pdf

Sharif University of Technology Sharif Journal of Civil Engineering 2676-4768 41 2 2025 09 22 Mathematical Modeling of Uncertainty in River Cross-Sections on Hydrodynamic Parameters of Steady Flow Mathematical Modeling of Uncertainty in River Cross-Sections on Hydrodynamic Parameters of Steady Flow 28 41 23726 10.24200/j30.2024.64363.3320 FA Razieh Valizadeh Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran. Mehdi Mazaheri Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran. Jamal Mohammad Vali Samani Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran. Journal Article 2024 04 13 In order to analyze the uncertainty of the geometric characteristics of the river on the hydrodynamic model, the uncertainty of the river cross-sections was investigated for a hypothetical example and a real river. Accordingly, taking into account 5%, 10% and 20% errors in the harvested points and ±6%, ±3% and 0 errors in the entire section, 15 scenarios were defined for generating new cross-sections. In order to investigate the effect of the selected distribution in generating random points on the output results, the random points of each section in each of the proposed scenarios were generated once by normal distribution and once again by uniform distribution. Five statistical indicators were used in river analysis mode and section by section analysis to analyze the two characteristics of the flow output, i.e. velocity and cross-sectional area. The results indicate that with the increase of the error in picking the points of each cross-section, the thickness of the 95% confidence interval, the coefficient of variation, the dispersion index and the result of dividing the actual value of each characteristic by the deviation from the criterion of that characteristic in different repetitions for both river and cross-sectional conditions increases. This is despite the fact that increasing the error of the entire section does not change much in the output of the results. By comparing the results of the two mentioned distributions, the uncertainty indices in the scenarios implemented with a uniform distribution show more dispersion.The result of dividing the thickness of the 95% confidence interval by the standard deviation of the data in each scenario in both distributions is also around a constant axis with little fluctuation in change. The results of the investigation of two types of systematic and random errors showed that the change of systematic error does not impose uncertainty on the output of the model. Also, in the case of normal error distribution, with the increase of the percentage of error, the statistical indicators change in such a way that the statistical indicators do not undergo unacceptable fluctuations up to the 20% error that was investigated in this study. In order to analyze the uncertainty of the geometric characteristics of the river on the hydrodynamic model, the uncertainty of the river cross-sections was investigated for a hypothetical example and a real river. Accordingly, taking into account 5%, 10% and 20% errors in the harvested points and ±6%, ±3% and 0 errors in the entire section, 15 scenarios were defined for generating new cross-sections. In order to investigate the effect of the selected distribution in generating random points on the output results, the random points of each section in each of the proposed scenarios were generated once by normal distribution and once again by uniform distribution. Five statistical indicators were used in river analysis mode and section by section analysis to analyze the two characteristics of the flow output, i.e. velocity and cross-sectional area. The results indicate that with the increase of the error in picking the points of each cross-section, the thickness of the 95% confidence interval, the coefficient of variation, the dispersion index and the result of dividing the actual value of each characteristic by the deviation from the criterion of that characteristic in different repetitions for both river and cross-sectional conditions increases. This is despite the fact that increasing the error of the entire section does not change much in the output of the results. By comparing the results of the two mentioned distributions, the uncertainty indices in the scenarios implemented with a uniform distribution show more dispersion.The result of dividing the thickness of the 95% confidence interval by the standard deviation of the data in each scenario in both distributions is also around a constant axis with little fluctuation in change. The results of the investigation of two types of systematic and random errors showed that the change of systematic error does not impose uncertainty on the output of the model. Also, in the case of normal error distribution, with the increase of the percentage of error, the statistical indicators change in such a way that the statistical indicators do not undergo unacceptable fluctuations up to the 20% error that was investigated in this study.

https://sjce.journals.sharif.edu/article_23726_11b4076afd563b2612049c2c77465b32.pdf

Sharif University of Technology Sharif Journal of Civil Engineering 2676-4768 41 2 2025 09 22 Investigation of Liquefiable Sandy Soil Improvement by Ordinary and Geotextile-Reinforced Stone Columns Using a Small-Scale Shaking Table Investigation of Liquefiable Sandy Soil Improvement by Ordinary and Geotextile-Reinforced Stone Columns Using a Small-Scale Shaking Table 42 57 23665 10.24200/j30.2024.64343.3319 FA Parna Yarbakhti Faculty of Civil and Environmental Engineering, Tarbiat Modares University, Tehran, Iran Aliakbar Golshani Faculty of Civil and Environmental Engineering, Tarbiat Modares University, Tehran, Iran 0000-0001-9986-0454 Journal Article 2024 04 28 The increase in construction in coastal cities, which are prone to liquefaction due to the high level of underground water and soil type, along with their soil conditions that do not meet the technical requirements, has led engineers to undertake soil improvement. Among the liquefaction mitigation methods, the stone column technique has been considered one of the most versatile and economical ground improvement techniques, including increasing the density of surrounding soil by vibration and replacement, expediting drainage, and reducing the shear stress of surrounding soil by introducing stiff elements. This study evaluated the seismic performance of stone columns and full- and partial-length geotextile-encased stone columns as a liquefaction countermeasure in the loose sample of Firoozkooh No. 161 sand. The sands were susceptible to liquefaction in a loose state, i.e., around 25% relative density, when subjected to a sinusoidal acceleration of 0.35g and 3Hz frequency. A group of nine ordinary and geotextile-reinforced stone columns with a diameter and length of 5 cm and 50 cm, respectively, has been created. In order to evaluate the seismic behavior, four reduced-scale 1-g model tests were conducted using a uniaxial shake table on a group of ordinary and geotextile-reinforced stone columns. Based on the obtained results, reinforcing the full length of the stone columns using geotextile has prevented liquefaction in the surface layers, reduced the excess pore water pressure ratio, increased the soil stiffness, and overall, has provided more effective performance than ordinary stone columns. The increase in construction in coastal cities, which are prone to liquefaction due to the high level of underground water and soil type, along with their soil conditions that do not meet the technical requirements, has led engineers to undertake soil improvement. Among the liquefaction mitigation methods, the stone column technique has been considered one of the most versatile and economical ground improvement techniques, including increasing the density of surrounding soil by vibration and replacement, expediting drainage, and reducing the shear stress of surrounding soil by introducing stiff elements. This study evaluated the seismic performance of stone columns and full- and partial-length geotextile-encased stone columns as a liquefaction countermeasure in the loose sample of Firoozkooh No. 161 sand. The sands were susceptible to liquefaction in a loose state, i.e., around 25% relative density, when subjected to a sinusoidal acceleration of 0.35g and 3Hz frequency. A group of nine ordinary and geotextile-reinforced stone columns with a diameter and length of 5 cm and 50 cm, respectively, has been created. In order to evaluate the seismic behavior, four reduced-scale 1-g model tests were conducted using a uniaxial shake table on a group of ordinary and geotextile-reinforced stone columns. Based on the obtained results, reinforcing the full length of the stone columns using geotextile has prevented liquefaction in the surface layers, reduced the excess pore water pressure ratio, increased the soil stiffness, and overall, has provided more effective performance than ordinary stone columns.

https://sjce.journals.sharif.edu/article_23665_c73568630a7d05a2da9940e239c63242.pdf

Sharif University of Technology Sharif Journal of Civil Engineering 2676-4768 41 2 2025 08 23 An Integrated Approach for Simulation of Two-Phase Flows in Naturally Fractured Reservoirs Using Embedded Discrete Fracture Model and Aerial Image Processing An Integrated Approach for Simulation of Two-Phase Flows in Naturally Fractured Reservoirs Using Embedded Discrete Fracture Model and Aerial Image Processing 58 69 23639 10.24200/j30.2024.64497.3331 FA Ali Heshmati Department of Mechanical Engineering of Sharif University of Technology, Tehran, Iran. Mehrdad Taghizadeh Manzari Department of Mechanical Engineering of Sharif University of Technology, Tehran, Iran. 0000-0003-0297-7053 Journal Article 2024 05 14 This paper introduces an integrated approach for simulating two-phase flows in naturally fractured reservoirs. The proposed computational process comprises two key steps: 1) generating a representation of the fracture network from aerial images using image processing techniques, 2) conducting two-phase flow simulations using the Embedded Discrete Fracture Method (EDFM). The reservoir contains only oil and water as immiscible incompressible fluids, with the assumption that the fracture system matches surface outcrop observations. Python libraries are utilized for image processing to convert aerial images into a fracture system defined by line segments. The effect of various tuning parameters, such as image resolution and edge detection, on the final fracture model is investigated. Once a robust fracture system representation is achieved, the reservoir geometry is defined, and boundary conditions are set. The problem is solved using the MATLAB Reservoir Simulation Toolbox (MRST), which includes an EDFM module for accurate analysis of naturally fractured reservoirs by incorporating detailed information, yielding precise fluid flow predictions. All types of fracture-matrix and fracture-fracture intersections and fluid exchanges between matrix and fractures are incorporated in the EDFM. Simulation results are verified against a benchmark problem, and the influence of rock and fracture physical properties on the flow field is examined. The study finds that rock permeability significantly affects fluid flow compared to fracture aperture or permeability. For instance, a 3 percent decrease in oil production is observed when increasing fracture aperture from 0.15 (mm) to 0.21 (mm), while increasing the matrix permeability from 1 to 20 millidarcy leads to a 22 percent increase. This paper introduces an integrated approach for simulating two-phase flows in naturally fractured reservoirs. The proposed computational process comprises two key steps: 1) generating a representation of the fracture network from aerial images using image processing techniques, 2) conducting two-phase flow simulations using the Embedded Discrete Fracture Method (EDFM). The reservoir contains only oil and water as immiscible incompressible fluids, with the assumption that the fracture system matches surface outcrop observations. Python libraries are utilized for image processing to convert aerial images into a fracture system defined by line segments. The effect of various tuning parameters, such as image resolution and edge detection, on the final fracture model is investigated. Once a robust fracture system representation is achieved, the reservoir geometry is defined, and boundary conditions are set. The problem is solved using the MATLAB Reservoir Simulation Toolbox (MRST), which includes an EDFM module for accurate analysis of naturally fractured reservoirs by incorporating detailed information, yielding precise fluid flow predictions. All types of fracture-matrix and fracture-fracture intersections and fluid exchanges between matrix and fractures are incorporated in the EDFM. Simulation results are verified against a benchmark problem, and the influence of rock and fracture physical properties on the flow field is examined. The study finds that rock permeability significantly affects fluid flow compared to fracture aperture or permeability. For instance, a 3 percent decrease in oil production is observed when increasing fracture aperture from 0.15 (mm) to 0.21 (mm), while increasing the matrix permeability from 1 to 20 millidarcy leads to a 22 percent increase.

https://sjce.journals.sharif.edu/article_23639_ba96dac54c2c763e2bd077c7753ce6c1.pdf

Sharif University of Technology Sharif Journal of Civil Engineering 2676-4768 41 2 2025 09 22 Decentralized Urban Runoff Management with Emphasis Upon On-Site Runoff Pollution Reduction: A Systematic Review Decentralized Urban Runoff Management with Emphasis Upon On-Site Runoff Pollution Reduction: A Systematic Review 70 89 23629 10.24200/j30.2024.64134.3307 FA Farkhondeh Khorashadi Zadeh Water and Environmental Engineering Group, Department of Civil Engineering, Sharif University of Technology, Tehran, Iran. Mohadese Shafiei Department of Civil Engineering, Sharif University of Technology, Tehran, Iran. Leila Mosleh Department of Water Engineering Sciences, Faculty of Agriculture, University of Sciences and Research, Tehran, Iran. Ali Asadi Department of Urban Management and Urban Engineering, University of Tehran, Tehran, Iran. Mohammadreza Jabehdari Systems Engineering, Morgan State University, United States. Alireza Moghaddam Nia 6. Department of Environmental Sciences and Technologies, Faculty of Energy and Sustainable Resources Engineering. Faculty of Interdisciplinary Sciences and Technologies, University of Tehran, Tehran, Iran. Journal Article 2024 03 12 Urban development has resulted in an increase in impermeable surfaces, and consequently, volume and peak discharge of surface runoff. In Addition, it perturbs the natural water cycle, including reduced pervious surfaces and increased surface runoff volume. Urban development engenders multifaceted issues, encompassing urban flood, degradation of surface water and groundwater quality, and a drop in groundwater levels. Conventional urban runoff management has usually adhered to a centralized approach, relying upon the construction of structural elements such as concrete channels to divert runoff. In recent decades, in order to diminish the deleterious impacts of urbanization, modern and decentralized methodologies have been introduced to mitigate the peak flow, volume, and pollution load of urban runoff by restoring the natural hydrological conditions before urban development. In different countries around the world, these strategies have been introduced and implemented by different terminologies, such as low-impact development, green infrastructure, sustainable urban drainage systems, water-sensitive urban design, and sponge cities. This research seeks to study the pioneering decentralized approaches of urban runoff management, introducing their benefits and comparing their efficacy in controlling contaminated runoff. Moreover, the challenges and limitations of each approach are discussed. By investigating the experiences of pioneering countries and successful projects, the feasibility of deploying these strategies and also the optimal conditions for the implementation of each approach in the metropolises of Iran are precisely assessed. Decision-makers and urban planners can benefit from this research in order to apply these approaches in Iranian cities, notably the expansive metropolis of Tehran. Reviewing the existing global and national experiences in this field shows that, in general, none of the Best Management Practices (BMPs) and Low Impact Developments (LIDs) techniques can alone meet all the goals of runoff management. Examining different scenarios of combining low-impact development methods using modeling is necessary to choose the most effective and economic scenario according to the characteristics of the study area. SWMM and SUSTAIN are among the widely used modeling tools in this field. Finally, the use of various decentralized techniques in each region should be based on observing all the technical principles and criteria related to their design, implementation, maintenance, and exploitation. In this context, reviewing the guidelines of different regions of the world can be helpful, but local studies should be done to evaluate the effectiveness of the discussed approaches, especially in terms of reducing the types of pollutants present in the runoff entering the facility. Urban development has resulted in an increase in impermeable surfaces, and consequently, volume and peak discharge of surface runoff. In Addition, it perturbs the natural water cycle, including reduced pervious surfaces and increased surface runoff volume. Urban development engenders multifaceted issues, encompassing urban flood, degradation of surface water and groundwater quality, and a drop in groundwater levels. Conventional urban runoff management has usually adhered to a centralized approach, relying upon the construction of structural elements such as concrete channels to divert runoff. In recent decades, in order to diminish the deleterious impacts of urbanization, modern and decentralized methodologies have been introduced to mitigate the peak flow, volume, and pollution load of urban runoff by restoring the natural hydrological conditions before urban development. In different countries around the world, these strategies have been introduced and implemented by different terminologies, such as low-impact development, green infrastructure, sustainable urban drainage systems, water-sensitive urban design, and sponge cities. This research seeks to study the pioneering decentralized approaches of urban runoff management, introducing their benefits and comparing their efficacy in controlling contaminated runoff. Moreover, the challenges and limitations of each approach are discussed. By investigating the experiences of pioneering countries and successful projects, the feasibility of deploying these strategies and also the optimal conditions for the implementation of each approach in the metropolises of Iran are precisely assessed. Decision-makers and urban planners can benefit from this research in order to apply these approaches in Iranian cities, notably the expansive metropolis of Tehran. Reviewing the existing global and national experiences in this field shows that, in general, none of the Best Management Practices (BMPs) and Low Impact Developments (LIDs) techniques can alone meet all the goals of runoff management. Examining different scenarios of combining low-impact development methods using modeling is necessary to choose the most effective and economic scenario according to the characteristics of the study area. SWMM and SUSTAIN are among the widely used modeling tools in this field. Finally, the use of various decentralized techniques in each region should be based on observing all the technical principles and criteria related to their design, implementation, maintenance, and exploitation. In this context, reviewing the guidelines of different regions of the world can be helpful, but local studies should be done to evaluate the effectiveness of the discussed approaches, especially in terms of reducing the types of pollutants present in the runoff entering the facility.

https://sjce.journals.sharif.edu/article_23629_3f90bf0094b4d5585ba7bf466e6b90fd.pdf

Sharif University of Technology Sharif Journal of Civil Engineering 2676-4768 41 2 2025 09 22 A Review of the Physics of Debris Flows and the Significance of Employing the Unsaturated Soil Conditions in Estimating the Erosion Volume A Review of the Physics of Debris Flows and the Significance of Employing the Unsaturated Soil Conditions in Estimating the Erosion Volume 90 103 23613 10.24200/j30.2024.64086.3304 FA Anahita Aghagoli Department of Civil Engineering, Sharif University of Technology, Tehran, Iran. Hamed Sadeghi Department of Civil Engineering, Sharif University of Technology, Tehran, Iran. 0000-0002-3453-9309 Journal Article 2024 02 20 Debris flows are natural disasters in mountainous regions and are formed when loose sedimentary deposits are carried by runoff and flow rapidly downslope. They are known for their high sediment concentrations and fast movements, which can cause significant casualties and damage to infrastructures. In contrast to floods and rock avalanches, where only one of the fluid or solid phases affects their dynamics, debris flows are influenced by both fluid and solid phases. In recent decades, the occurrence of these flows has increased due to climate change. Predicting and managing damages caused by these flows requires a systematic approach that involves identifying the causes, estimating the volume and distance, and assessing vulnerable areas and at-risk infrastructures. However, the interaction between solid and fluid phases gives rise to complexity in interpreting the development process. This complexity becomes even more exacerbated when it comes to employing the principles of unsaturated soil mechanics to investigate the behavior of unsaturated debris flows and the occurrence of unsaturated bed erosion. In this review paper, some of the factors influencing the behavior of debris flows, their physics, and the complex interactions between the flowing mass and the erosive bed, particularly unsaturated beds, are summarized and discussed. It is highlighted that the high mobility of the debris flows results in sudden and rapid fluctuations in stress-independent variables. These fluctuations can create regions of increased and decreased resistance, leading to localized variations in the stability of the flow. Based on the analysis of the existing literature, it can be concluded that there are limited numerical models capable of adequately capturing the instantaneous nature of debris flows. As a result, there is a strong need for the development of appropriate theoretical frameworks. Furthermore, in saturated soils, the pore pressure diffusion time decreases with increasing permeability. The pore pressure in these beds, therefore, dissipates rapidly during erosion. In contrast, the pore pressure diffusion time is longer in unsaturated beds. Consequently, with an increase in the water content, the erosion rate becomes significantly faster. This, in turn, results in a more significant flow momentum in wet beds compared to dryer ones. Debris flows are natural disasters in mountainous regions and are formed when loose sedimentary deposits are carried by runoff and flow rapidly downslope. They are known for their high sediment concentrations and fast movements, which can cause significant casualties and damage to infrastructures. In contrast to floods and rock avalanches, where only one of the fluid or solid phases affects their dynamics, debris flows are influenced by both fluid and solid phases. In recent decades, the occurrence of these flows has increased due to climate change. Predicting and managing damages caused by these flows requires a systematic approach that involves identifying the causes, estimating the volume and distance, and assessing vulnerable areas and at-risk infrastructures. However, the interaction between solid and fluid phases gives rise to complexity in interpreting the development process. This complexity becomes even more exacerbated when it comes to employing the principles of unsaturated soil mechanics to investigate the behavior of unsaturated debris flows and the occurrence of unsaturated bed erosion. In this review paper, some of the factors influencing the behavior of debris flows, their physics, and the complex interactions between the flowing mass and the erosive bed, particularly unsaturated beds, are summarized and discussed. It is highlighted that the high mobility of the debris flows results in sudden and rapid fluctuations in stress-independent variables. These fluctuations can create regions of increased and decreased resistance, leading to localized variations in the stability of the flow. Based on the analysis of the existing literature, it can be concluded that there are limited numerical models capable of adequately capturing the instantaneous nature of debris flows. As a result, there is a strong need for the development of appropriate theoretical frameworks. Furthermore, in saturated soils, the pore pressure diffusion time decreases with increasing permeability. The pore pressure in these beds, therefore, dissipates rapidly during erosion. In contrast, the pore pressure diffusion time is longer in unsaturated beds. Consequently, with an increase in the water content, the erosion rate becomes significantly faster. This, in turn, results in a more significant flow momentum in wet beds compared to dryer ones.

https://sjce.journals.sharif.edu/article_23613_f66d6e86ad128c934d9f1c3ea9d19155.pdf

Sharif University of Technology Sharif Journal of Civil Engineering 2676-4768 41 2 2025 09 22 Providing a Pricing Model for Shuttle Taxi Services in Isfahan City Providing a Pricing Model for Shuttle Taxi Services in Isfahan City 104 113 23604 10.24200/j30.2024.63375.3270 FA Amin Najafi Faculty of Civil Engineering, Road and Transportation Engineering, Islamic Azad University, Najaf Abad branch. Amir Masoud Rahimi Department of Civil Engineering, Faculty of Engineering, University of Zanjan, Zanjan, Iran. Mohsen Aboutalebi Isfahani Department of Railway Engineering and Transportation Planning, Faculty of Civil Engineering and Transportation, University of Isfahan, Isfahan, Iran. Journal Article 2023 11 04 In the city of Isfahan, taxi lines, as one of the most widely used methods of public transportation, make a significant contribution to the daily movement of people. The current fares are set in a way that not only do they not meet the costs of the service providers, but also lead to the dissatisfaction of the drivers and passengers. Therefore, the necessity of revising the pricing system of shuttle taxi services in order to fully cover the costs, the profit of the drivers, and the satisfaction of the passengers is clearly felt. This research is based on the assumptions that form its basis, including the lack of response of the current fares to the costs of providing taxi services and the failure to consider the time parameter in the pricing of taxi services. The main goal of this research is to determine pricing in a way that covers all the costs of providing the service, along with a certain profit for the taxi providers. The research method in this study focuses on price modeling based on the final cost method. First, the parameters affecting the price have been identified, and then the contribution of each parameter to the total cost has been determined. In the following, the navigation cost for each kilometer is calculated, and finally, a price model that includes all costs along with 20% profit for four different modes of operating a shuttle taxi is presented. Taxi fares are calculated based on the distance and travel time of passengers, and different pricing strategies are used for different hours to manage demand. This strategy sets prices higher during peak hours and lower during off-peak hours to help manage demand. This method will encourage people to use taxis during off-peak hours, and at the same time, the promotion of drivers to provide services during high-traffic hours will remain. The results of this research provide valuable insight into the pricing dynamics of taxi services in different conditions and based on the length of different routes. For example, the cost of traveling by Samand taxi is 32183 riyals per kilometer. Also, in the conditions of traffic congestion, the increase in the cost of each kilometer of travel has been calculated to be 38016 Riyals. These results show that for long distances, such as the Bozorgmehr Bridge-Khorasgan University, the current fares are not enough to cover the costs. In the city of Isfahan, taxi lines, as one of the most widely used methods of public transportation, make a significant contribution to the daily movement of people. The current fares are set in a way that not only do they not meet the costs of the service providers, but also lead to the dissatisfaction of the drivers and passengers. Therefore, the necessity of revising the pricing system of shuttle taxi services in order to fully cover the costs, the profit of the drivers, and the satisfaction of the passengers is clearly felt. This research is based on the assumptions that form its basis, including the lack of response of the current fares to the costs of providing taxi services and the failure to consider the time parameter in the pricing of taxi services. The main goal of this research is to determine pricing in a way that covers all the costs of providing the service, along with a certain profit for the taxi providers. The research method in this study focuses on price modeling based on the final cost method. First, the parameters affecting the price have been identified, and then the contribution of each parameter to the total cost has been determined. In the following, the navigation cost for each kilometer is calculated, and finally, a price model that includes all costs along with 20% profit for four different modes of operating a shuttle taxi is presented. Taxi fares are calculated based on the distance and travel time of passengers, and different pricing strategies are used for different hours to manage demand. This strategy sets prices higher during peak hours and lower during off-peak hours to help manage demand. This method will encourage people to use taxis during off-peak hours, and at the same time, the promotion of drivers to provide services during high-traffic hours will remain. The results of this research provide valuable insight into the pricing dynamics of taxi services in different conditions and based on the length of different routes. For example, the cost of traveling by Samand taxi is 32183 riyals per kilometer. Also, in the conditions of traffic congestion, the increase in the cost of each kilometer of travel has been calculated to be 38016 Riyals. These results show that for long distances, such as the Bozorgmehr Bridge-Khorasgan University, the current fares are not enough to cover the costs.

https://sjce.journals.sharif.edu/article_23604_5e7a1b6c04257d714c85fd3f0be580b2.pdf

Sharif University of Technology Sharif Journal of Civil Engineering 2676-4768 41 2 2025 09 22 Investigating the Effect of Gorgan Bay’s Sludge Ash on the Mechanical Parameters of Gorgan Loess Soil at Different Moisture Content and the Same Compaction Energy Investigating the Effect of Gorgan Bay’s Sludge Ash on the Mechanical Parameters of Gorgan Loess Soil at Different Moisture Content and the Same Compaction Energy 114 123 23653 10.24200/j30.2024.64158.3314 FA Vahid Pesarakloo Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran 0000-0003-4643-937X Seyed Hamid LAJEVARDI Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran Hossein MolaAbasi Department of Civil Engineering, Gonbad Kavous University, Gonbad Kavous, Iran 0000-0002-4552-5551 Seyed Mohammad MIrHosseini Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran Journal Article 2024 04 15 The objective of this study is to examine the mechanical properties of Gorgan loess enhanced with sludge pond ash (SPA) from Gorgan Gulf under different conditions. To achieve this, different proportions of SPA were mixed with the loess to obtain accurate findings on the efficacy of SPA addition on the unconfined compressive strength (UCS), cohesion (C), friction angle (f), compression (Cc), and recompression (Cs) index of the loess. Firstly, the sludge from a pond burned at 1000°C, which was the optimal temperature determined by X-ray fluorescence analysis (XRF), was added to the mixture as 0, 2, 4, 6, 8, and 10% of the soil's dry weight, respectively. The studied samples were prepared with the same energy (equivalent to the standard Proctor test) at different moisture contents (16, 18.5, 21, 23.5, and 26%) and were tested in unconfined compressive strength, direct shear, and consolidation devices at 56 days of curing in a humid room with a temperature of 24°C. It was found that adding SPA to the base soil increases the maximum strength measured in unconfined compressive strength, which is defined as unconfined compressive strength (UCS). On the other hand, it decreased with increasing moisture content. The addition of SPA as an additive material to the loess mixture was found to exert a significant effect on the shear strength properties (C and f) of the loess. The changes in moisture percentage for this test were not specific due to soil saturation and consolidation, and did not have a great effect on the increase of shear strength parameters with the increase of SPA. Examining the graphs of the consolidation test shows that the addition of 2% of SPA to the loess caused a noticeable decrease in the amount of Cc of the sample under the test after processing. Increasing the amount of SPA up to 10% caused a further decrease in the Cc value of the samples. This trend is also noticeable for the re-compression index, which showed a greater intensity with the increase in the amount of SPA. Accordingly, adding SPA to the soil caused a sharp decrease in Cs in the samples compared to the base soil. At the end, the results of macro-scale analyses collectively confirm the superior efficacy of the SPA replacement in enhancing various strength and stiffness properties of the loess. The objective of this study is to examine the mechanical properties of Gorgan loess enhanced with sludge pond ash (SPA) from Gorgan Gulf under different conditions. To achieve this, different proportions of SPA were mixed with the loess to obtain accurate findings on the efficacy of SPA addition on the unconfined compressive strength (UCS), cohesion (C), friction angle (f), compression (Cc), and recompression (Cs) index of the loess. Firstly, the sludge from a pond burned at 1000°C, which was the optimal temperature determined by X-ray fluorescence analysis (XRF), was added to the mixture as 0, 2, 4, 6, 8, and 10% of the soil's dry weight, respectively. The studied samples were prepared with the same energy (equivalent to the standard Proctor test) at different moisture contents (16, 18.5, 21, 23.5, and 26%) and were tested in unconfined compressive strength, direct shear, and consolidation devices at 56 days of curing in a humid room with a temperature of 24°C. It was found that adding SPA to the base soil increases the maximum strength measured in unconfined compressive strength, which is defined as unconfined compressive strength (UCS). On the other hand, it decreased with increasing moisture content. The addition of SPA as an additive material to the loess mixture was found to exert a significant effect on the shear strength properties (C and f) of the loess. The changes in moisture percentage for this test were not specific due to soil saturation and consolidation, and did not have a great effect on the increase of shear strength parameters with the increase of SPA. Examining the graphs of the consolidation test shows that the addition of 2% of SPA to the loess caused a noticeable decrease in the amount of Cc of the sample under the test after processing. Increasing the amount of SPA up to 10% caused a further decrease in the Cc value of the samples. This trend is also noticeable for the re-compression index, which showed a greater intensity with the increase in the amount of SPA. Accordingly, adding SPA to the soil caused a sharp decrease in Cs in the samples compared to the base soil. At the end, the results of macro-scale analyses collectively confirm the superior efficacy of the SPA replacement in enhancing various strength and stiffness properties of the loess.

https://sjce.journals.sharif.edu/article_23653_3630391d291abc67bf9daec2c332829c.pdf