Ehsan Pegah,
Volume 17, Issue 2 (9-2023)
Abstract
The ratios of elastic anisotropy in cohesionless soils are always of substantial importance in respective analyses to the geotechnical and geological engineering projects. These ratios are raising from the available discrepancies in anisotropic elastic parameters ascribed to the different directions and planes of soil mass. The major objective of this study is to recognize the variations range of anisotropy ratios resulting from anisotropic shear and Young’s moduli for a variety of cohesionless soils followed by assessing the potential relations among these two anisotropies. To this end, by assuming the transversely isotropy in cohesionless soils, the anisotropic elastic constants from 266 conducted laboratory tests on 37 various soil specimens relating to 10 different sands were derived from conventional triaxial and seismic waves laboratory tests coupled with the numerical testing results in literature. By sorting the collected data and subsequently their analyses, at the first stage, the values of shear and Young’s moduli anisotropy ratios were calculated for the studied soils. Furthermore, by plotting the anisotropy ratios in several joint panels and performing a series of regression analyses on the resulting values, the possible dependencies were inspected between these two anisotropies. At last, the indicative equations among shear and Young’s moduli anisotropies were developed with insistence on use of which instead of the former similar relations in literature.
Khandani, Atapour, Yousefi Rad, Khosh,
Volume 17, Issue 3 (12-2023)
Abstract
Backfill materials used to fill underground mines are a type of engineered material whose particle size distribution (PSD) directly affects their mechanical and physical properties. According to the authors' review, there is no comprehensive standard for the properties of aggregates used in underground mine backfill materials. In this paper, the particle size ranges and particle size distribution curves of various mine backfill materials, including hydraulic backfill, paste backfill and rock backfill, have been reviewed. The available data on different types of backfill materials were collected. Based on the collected data, the smallest particle size, the largest particle size and the PSD curve ranges for each type of backfill material were determined. Then the characteristics of the particle size distribution curve of each backfill material, including the mean particle diameter (D50), the uniformity coefficient (Cu) and the curvature coefficient (Cc), were calculated. The results of the analysis of the PSD curves for paste backfill, hydraulic backfill and rock backfill materials showed that the particles in rock backfill and paste backfill had the largest and smallest sizes, respectively. Finally, the particle size distribution characteristics of a new backfill material prepared from construction and demolition waste (CDW backfill) are presented and compared with the particle size distribution of each of the conventional backfill materials. The results indicate that the PSD curve of the CDW backfill lies at the upper limit of the range of the particle size distribution curve of hydraulic backfill and at the lower limit of the range of the particle size distribution curve of rock backfill.
Dr Masoud Amelsakhi, Eng Elham Tehrani,
Volume 17, Issue 4 (12-2023)
Abstract
This research is a laboratory study to improve the geotechnical properties of sandy soils. Concrete waste with a grain size of 1.2 to 1 inch was used for this purpose. The effect of using concrete waste at 0, 10, 20 and 30 weight percent on dry sandy soil in two loose and dense states was investigated. Based on the results of the direct cutting test, the addition of concrete waste has increased the shear strength and the internal friction angle of the soil; The loose samples made with ٪30 of concrete waste had the greatest effect, so adding ٪30 of concrete waste to loose sand increased the internal friction angle of the soil by ٪32 and the shear strength by ٪42 Similarly, adding ٪10 of concrete waste to dense sand increased the internal angle of friction of the soil by ٪4 and the shear strength by ٪6.
Eng. Zahra Soleimani, Dr. Ebrahim Rahimi, Dr. Houshang Khairy,
Volume 18, Issue 1 (5-2024)
Abstract
This article deals with the strength evaluation of concrete obtained by adding different percentages of three types of nanominerals, including nanocalcite, nanobarite and nanofluorite. To measure the velocity of ultrasonic waves and compressive strength of concrete, 15×15×15 cm cube samples were prepared with 7-, 28- and 90-days curing. 10 types of mix designs with 0.39 water-cement ratio, including the control sample (without additives) and the samples with 0.5, 0.75 and 1% nanominerals were subjected to the mentioned tests. The results showed that the addition of nanocalcite, nanofluorite, and nanobarite with values of 0.75%, 1%, and 0.75%, respectively, have the highest compressive strength compared to the control sample. Although these do not have pozzolanic properties, they play a positive role in increasing the concrete strength by filling concrete voids and due to their high specific gravity, increasing concrete density.
Dr Sayed Ali Asghari Pari,
Volume 18, Issue 1 (5-2024)
Abstract
Pile design is subject to a number of uncertainties that must be addressed to ensure the reliability and safety of the foundation. A common approach to reduce uncertainties in pile design is to calibrate the resistance factor in the Load and Resistance Factor Design (LRFD) method through reliability analysis. However, it is important to recognize that the LRFD method may not fully account for uncertainties associated with soil and pile resistances. The results of this study show that the separate consideration of base and wave resistance can lead to a more accurate and reliable design of piles. The proposed method can help engineers make more informed decisions and reduce uncertainties in pile design. In addition, the study highlights the importance of considering different factors such as the ratio of dead to live load and the ratio of base to shaft resistance when calculating the resistance factor.
Ms Roghayeh Hasani, Dr Ebrahim Asghari-Kaljahi, Dr Sina Majidiana,
Volume 18, Issue 2 (9-2024)
Abstract
With the expansion of the petroleum industry and the aging of facilities and pipelines, oil spills are becoming more frequent. In addition to environmental impacts, oil spills can cause changes in the plasticity and dispersivity of soils. To investigate the potential for dispersion in fine-grained soils due to oil leakage, soil samples were collected from the Shazand Refinery area in Arak and mixed with 0, 5, 10, 15, and 20% by weight crude oil. Specimens were prepared at the maximum dry density obtained from the Proctor compaction test and, after curing, pinhole and double hydrometer tests were conducted. The results of the mentioned tests showed that the fine-grained soil tends to disperse with the addition of up to 15% oil, and this dispersion increases with further increases to 20%. Changes in the soil fabric with increasing oil content were investigated using scanning electron microscopy (SEM) images, and the results showed that the dispersion of soil particles increased with increasing oil content.
Dr Mehran Esfahanizadeha, Dr Mohamad Davoodi, Dr Ebrahim Haghshenas, Dr Mohamad Kazem Jafari,
Volume 18, Issue 2 (9-2024)
Abstract
The determination ofgeological subsurface strata and shear wave velocity profiles is one of the most important engineering measures for seismic design and site effects studies. Recently, the use of seismic geophysical methods in engineering geological studies for this purpose has become widespread. In this paper, the accuracy and efficiency of seismic geophysical methods with active and passive seismic source in determining the subsurface geological structure of a selected site in the city of Abasabad in northern Iran have been studied. To this end, first, by conducting several exploratory boreholes, the subsurface geological structure of the study site up to a depth of 70 meters was carefully determined using engineering geological experiments. The results of this section showed that the shallow sediments of Abasabad site are mainly composed of sandy soils with four separate geological layers. In the next step, in two other separate boreholes, seismic geophysical experiments with active source of down-hole test were performed in order to accurately determine the shear wave velocity profile in different layers. In addition, in the next phase, using the array microtremor recording method, which is a new seismic geophysical method of passive-source type, to determine the subsurface geological structure of the study site in the form of shear wave velocity profiles. It should be noted that the array microtremor recording was performed using fifteen different arrangements of receptors (with different numbers and distances of receptors) and by two analyzing methods including F-K and SPAC. The results of these studies showed that both active and passive seismic geophysical methods had acceptable performance in determining the subsurface geological stratification of the site. It also could be inferred that the down-hole test with high accuracy determines the shear wave velocity in each layer compared to the array microtremor method but requires artificial production of seismic waves and borehole drilling. Array microtremor method without the need for drilling and production of artificial seismic waves has high efficiency in determining the subsurface layering and estimating the shear wave velocity of each layer and in general the results of this paper showed that in estimating the shear wave velocity compared to down-hole method shows up to 10% error.
Dr Masoud Amelsakhi,
Volume 18, Issue 3 (12-2024)
Abstract
Tunnels behave differently under seismic conditions due to their geometric shape, geotechnical parameters and installation depth. Although tunnels are less damaged compared to surface structures, they are still damaged during earthquakes. Various experiences have proved this matter, so researchers are concerned to study the seismic behavior of tunnels. In this research, circular tunnels are discussed under static and pseudo-static loading. In addition to different pseudo static earthquake factors, internal soil friction angle, soil behavior models, sliding and non-sliding of tunnel wall are also studied. Three different soft, medium and stiff soil conditions are studied. Some results show that in all three soil conditions and two soil behavior models, Mohr-Coulomb and hardening soil, the horizontal displacements increase due to the increase of the pseudo static earthquake factor. It should be noted that softening of the soil increases the horizontal displacements.
Zahra Aghayan, Rouzbeh Dabiri,
Volume 18, Issue 3 (12-2024)
Abstract
Recently, the demand for rapid and cost-effective infrastructure development has led to the has led to the development of various soil improvement techniques, including stabilization. Studies on the incorporation of mineral materials such as lime and coal ash into soil stabilization have been carried out in several countries, and these studies have shown promising results. Given the beneficial properties or properties of coal ash, together with its availability and cost-effectiveness, the combination of coal ash with lime for clay soil stabilization is a viable option. This study evaluates lime and coal ash on the behavior and geotechnical properties of clay soils. The evaluation includes plasticity index (PI), compaction, uniaxial compressive strength, California bearing ratio (CBR) and direct shear tests, and direct shear tests. To achieve this, the process began with the mixing of clay with varying percentages of hydrated lime (4%, 6% and 7%), followed by a 28-day curing period for the samples. Coal ash was then added at different (5%, 15%, 25% and 50%) was incorporated into the clay and also cured for 28 days. In the final stage, the optimum amount of hydrated lime was determined, an amount of hydrated lime, equivalent to the amount of coal ash used, was added to the clay and the mixture was cured for a further 28 days. The results indicate that A mixture of 7% hydrated lime and 50% coal ash, after 28 days of curing, is an optimum combination for stabilizing the clay in the study area. This combination increased the uniaxial compressive strength by 1.87 times, the shear strength by 1.34 times and the CBR value by 6.4 times, making it suitable for use in the for use in the construction of pavement layers.
Dr Ali Ghanbari, Fatemeh Mirdar,
Volume 18, Issue 4 (12-2024)
Abstract
Examining the seismic response of the ground surface and its impact on structures due to topographic effects and soil-structure interaction (TSSI) is highly significant. If the site has sloping topography, the importance of this study is further amplified, and the slope effect on soil-structure interaction must be considered. This research uses Loma Prieta (1989) earthquake records to analyze the seismic response of a 5-story concrete building located 5 meters from the crest of the slope for four angles: 15, 30, 45, and zero degrees (SSI), using 3D numerical analysis. Modeling was conducted with MIDAS GTS NX software for both TSSI and SSI systems. An elastic model and an HSS model were used for the building and soil, respectively. The seismic response of the building was evaluated by comparing maximum lateral displacements, base shear forces, inter-story drifts, and horizontal accelerations in TSSI and SSI analyses. As the slope angle increased from zero degrees (SSI) to 15, 30, and 45 degrees (TSSI), the average lateral displacement of the floors increased by 44%, and the average maximum horizontal acceleration increased by 21%. Additionally, with the slope angle increasing from zero degrees (SSI) to 15, 30, and 45 degrees (TSSI), the average ratios of inter-story drift and maximum base shear force increased by 14% and 21%, respectively.
Amir Khoshgoftar, Mahdi Khodaparast,
Volume 18, Issue 5 (12-2024)
Abstract
Soil contamination by petroleum contaminants and their derivatives has harmful effects on the soil environment. The structure and geotechnical parameters of the soil will change as a result of the interaction between the contaminant and the soil. The double layer thickness of the clay will change, and the structure of the clay soil will become similar to that of the granular soil. In the present study the effect of contamination by burnt-oil waste from refineries on the compaction and resistance behavior of clayey sand soils was investigated. The geotechnical characteristics of soil types contaminated with different percentages of hydrocarbons from previous research were also reviewed and analyzed. The primary effects were decreases in the internal friction angle, California bearing ratio and permeability of the soil and increases in the cohesion and Atterberg limits of the soil. The shear strength of the contaminated soil did not show a definite or constant trend of change. When contaminated with acidic sludge, despite an increase in the cohesion of the soil, a decrease in the internal friction angle caused a decrease in the shear strength. When contaminated with dirt filter residue, the shear strength of the soil increased with the substantial increase in cohesion, despite a decrease in the internal friction angle.
Mr Mohammadreza Harirsaz, Dr Ali Ghanbari, Dr Gholamhosien Tavakoli Mehrjardi,
Volume 18, Issue 5 (12-2024)
Abstract
A series of reduced scale plate load tests was conducted to evaluate the bearing capacity of a strip footing resting on granular slopes. The effect of three factors including geocell burial depth, geocell length and spacing of geocell layers were discussed and evaluated. In this regard, 18 tests were performed to investigate the behavior of one and two layered geocell-reinforced slopes as well as the unreinforced slope and plain conditions. The results suggest that in single-layered geocell-reinforced slope, the optimum burial depth of the first layer of geocell reinforcement is 0.1 times of the strip footing width, whereas at greater depth beneficial effect of the geocell will reduce. In addition, expanding the reinforcement length up to approximately three times the foundation width could effectively increase the bearing capacity, whereas extending the length beyond that does not lead to any significant improvement. Furthermore, it was observed that use of two geocell layers by considering an optimum geocell space of 0.2 times of the foundation width could enhance the bearing capacity up to 226% in comparison with the unreinforced slope, and up to 79% of the plane condition for settlement ratio of 15%. Finally, the results indicate that the efficiency of the geocell reinforcements in lessening the gap between slope and plane conditions increases as the settlement of the footing rises due to better mobilization of dilation characteristics of granular backfill material and better lateral confinement of coarse aggregates in greater strains.
Soroush Mahdavian, Navid Rashidi, Ali Raeesi, Jamal Abdullahi,
Volume 19, Issue 1 (6-2025)
Abstract
Clay soils typically have low strength and a high swelling percentage. They are considered as problematic soils in Civil Engineering projects. This research study examined the effects of magnesium chloride (MgCl2) solution on the clay soil improvement through conducting laboratory experiments. The experimental program included Atterberg limits, compaction, swelling, unconfined compression strength (UCS) and Scanning Electron Microscopy (SEM) tests. Available clay soil in the Lab was mixed with MgCl2 solution at weight percentages of 3%, 5%, 7% and 10% Samples for the swelling and strength tests were made using thestatic compaction method. The moisture and dry unit weight of the prepared samples were the same as those of thecorresponding compaction curves. The strength test results showed that the final strengths of the samples with 3% MgCl₂ at 7-, 14-, and 28-day curing times were 1401, 2018, and 1848 kPa, respectively. The results also showed that a reduction in strength of the samples occurred with more than a 3% solution of MgCl₂. For samples with 10% MgCl2 solution, the strength decreased until 14 days of curing time, but increased thereafter. Additionally, the results indicated that the reduction in swelling percentage compared to natural soil was 4.95%, 3.98%, 2.8%, and 3.9% for samples with 3%, 5%, 7%, and 10% MgCl₂, respectively, showing that the reduction in swelling depends on the MgCl₂ percentage. Additionally, the SEM results showed that the improvement in the soil was due to chemical reactions between the soil and MgCl₂.
Mrs Roya Masoumipour, Dr. Saeed Mahdavi,
Volume 19, Issue 1 (6-2025)
Abstract
The Chador-Malu open-pit mine is faces complex challenges regarding the long-term stability of its slopes. These are directly influenced by time, environmental changes, and stresses induced by mining activities. Considering the existing evidence of potential future instability, displacement changes along the northern to eastern pit walls were analyzed over an 18-month period. Long-term wall displacements were measured using radar. Through back-analysis and three-dimensional numerical simulations, the equivalent creep behavior of the slopes was evaluated using the Maxwell creep model. After assessing the geomechanical parameters, the impact of three scenarios passage of time, bench widening, and pit deepening on slope stability was investigated under three horizontal-to-vertical stress ratios of 0.5, 1, and 1.5. The analysis results indicated that a horizontal-to-vertical stress ratio of 1.5 better matched the field observations. In the first scenario, a 50% increase in time led to over a 100% increase in displacement rates, indicating a rise in instability potential over time. In the second scenario, unloading the first two benches reduces the instability potential, due to an 18% reduction in uplift while unloading up to the eighth bench increased instability potential due to the reduction of weight at the slide’s toe and an increase in the average uplift. In the third scenario, pit deepening formed another sliding zone between the tenth and seventeenth benches.
Mohammad Reza Haddad Tehrani, Mehdi Talkhablou, Mohammad Reza Asef, Mehdi Ostad Hasan,
Volume 19, Issue 2 (10-2025)
Abstract
Complex carbonate reservoirs, such as the Asmari Formation, present challenges to the accurate determination of geomechanical parameters and effective stresses due to high lithological and structural heterogeneity. The objective of this study is to develop a comprehensive three-dimensional model of geomechanical parameters and effective stresses in the Kupal oil field. Well log, core, and seismic data were used, and three-dimensional modeling was performed using the Sequential Gaussian Simulation (SGS) method based on variogram analysis. The prevailing stress regime was validated using FMI logs and wellbore breakout analysis. Additionally, a one-at-a-time sensitivity analysis was conducted on key parameters, including static Young’s modulus, Poisson’s ratio, cohesion, internal friction angle, and pore pressure. Results indicate that the maximum vertical effective stress (σv) is 87 MPa and the maximum horizontal effective stress (σHmax) is 127 MPa. Analysis of wellbore imaging data confirms a normal faulting stress regime (σv>σHmax>σhmin) in the field. Stress concentration around minor faults was also identified. The model was validated against one-dimensional models achieving 88% agreement. The findings of this study can be applied to well design, gas injection, and reservoir stability assessment in the Kupal field.
Dr Seyed Ali Asghari Pari,
Volume 19, Issue 6 (12-2025)
Abstract
Various factors influence earth dams' stability and flow rate, including geometric characteristics, material permeability, and upstream water height. Understanding unsaturated soil behavior in earth dams is crucial, necessitating the application of unsaturated soil mechanics principles due to the complexities involved. This study investigates the effect of Soil-Water Characteristic Curve (SWCC) parameters on the slope stability of an earth dam under steady-state and rapid drawdown conditions. The findings reveal that SWCC parameters significantly influence water flow and slope stability. Additionally, considering unsaturated unit weight can improve slope stability under varying conditions.
Ms Solmaz Darsanj, Dr. Mehrdad Emami Tabrizi, Dr. Hassan Afshin,
Volume 19, Issue 6 (12-2025)
Abstract
Aeolian sands in arid and semi-arid regions are considered problematic soils due to their loose structure, low bearing capacity, and difficult compaction. The dry climatic conditions of Iran and phenomena such as the desiccation of Lake Urmia have intensified the dispersion of saline sands. One of the common approaches to mitigate these issues is chemical stabilization using additives such as cement. This study investigates the effect of stabilizing saline aeolian sands collected from the Lake Urmia basin using Type I Portland cement. Stabilized soil specimens were prepared with varying levels of salinity and different cement contents, and were subjected to unconfined compressive strength testing after a curing period of 7 days. The results demonstrated that increasing the cement content significantly enhances compressive strength. Moreover, the presence of salt in the studied soil did not hinder the stabilization process; instead, it contributed to improved strength in the short term. These findings underscore the importance of considering both the type and concentration of salts when designing stabilization treatments for saline granular soils in arid and semi-arid climates.
Masoud Khahanipour, Hossin Sarbaz,
Volume 19, Issue 6 (12-2025)
Abstract
The aim of this study is to numerically analyze the axial force, shear force, and horizontal displacement in the tunnel (Tunnel B on the Pataveh-Dehdasht axis). This tunnel is part of a national project, which was inaugurated and put into operation in the summer of 2023, with technical specifications including 2.2 million cubic meters of earthwork, construction of retaining walls with a total length of 2,100 meters, 110,000 tons of subbase and base layers, and 95,000 tons of asphalt.
In the present study, the effect of tunnel lining thickness on shear force, axial force, and both horizontal and vertical displacements was numerically investigated using the PLAXIS finite element software in a two-dimensional framework. Plane strain theory was employed with 15-node elements for modeling. For the surrounding soil, the Mohr-Coulomb constitutive model, which is one of the fundamental stages in numerical analysis and commonly used in most tunnel excavation simulations, was applied to model the soil behavior of the study site.
The results indicate that increasing the lining thickness reduces both vertical and horizontal displacements at all points, while axial and shear forces increase. The maximum deformation occurs at the tunnel invert, and the minimum occurs at the right-side wall of the tunnel. Increasing the lining thickness from 20 cm to 35 cm leads to an approximately 100% reduction in tunnel floor settlement and a significant decrease in horizontal displacement, exceeding 90% at certain points. The findings highlight that selecting an appropriate lining thickness plays a key role in controlling deformations, enhancing load-bearing capacity, and improving the seismic safety of the tunnel.
Keywords
Soroush Mahdavian, Ali Raeesi Estabragh, Shima Azadeh Ranjbar,
Volume 19, Issue 6 (12-2025)
Abstract
This research study investigated the impact of dimethyl phthalate (DMP) on the physical and mechanical properties of clay soil through experimental testing. Additionally, the impact of hydrated lime and magnesium oxide on improving the properties of clay soil was investigated. The contaminated soil was artificially produced in the laboratory. Natural and contaminated soils were mixed with the above agents at percentages of 5.0%, 10.0% and 15.0%, respectively. The experimental test programme for this study comprised: Atterberg limits, compaction, uniaxial compression tests (UCS) and scanning electron microscopy (SEM). Samples for the UCS tests, both with and without additives, were prepared using the static compaction method and tested at curing times of 7, 14 and 28 days. The results showed that, in general, the Atterberg limit, compaction parameter (maximum dry unit weight) and UCS values for the contaminated soil were lower than for the natural soil. The results also indicated a reduction in UCS values for a mixture of contaminated soil and 10% hydrated lime or magnesium oxide. A comparison of the final strength values of samples made from a mixture of contaminated soil and 10% hydrated lime or magnesium oxide showed that the strength was 34.4% and 63.8% lower than that of a mixture with 5% of these additives at the same curing time. The E50 values were calculated from the stress-strain curves of the different tests. Additionally, the SEM results showed that changes in the properties of the mixture prepared from these agents and natural or contaminated soil were due to a chemical reaction between the soil and the additives.
Reza Mohseni Afkham, Dr Mojtaba Bahaaddini, Dr Abbas Majdi,
Volume 19, Issue 6 (12-2025)
Abstract
Tensile strength is one of the most important mechanical properties of brittle materials and plays a decisive role in the stability of many civil and mining structures. The Brazilian test is the most common indirect method for determining tensile strength and is widely employed. In this test, it is generally assumed that a central tensile crack initiates and propagates along the loading axis. However, the actual fracture process in the Brazilian test remains a controversial issue, and using curved loading platens has been recommended to better concentrate tensile stresses at the center of specimen. This study investigated the influence of platen curvature on the estimated tensile strength and the fracture patterns. To this end, five types of platen with curvature ratios of 0, 0.50, 0.57, 0.67, and 0.80 were prepared. All tests were recorded using a high-speed camera to precisely capture the initiation and propagation of cracks. To minimize the effect of rock heterogeneity and obtain consistent results, synthetic specimens were used, and five samples were tested for each curvature ratio.The results indicated that increasing the platen curvature led to a higher estimated tensile strength. While the increase was negligible for curvature ratios up to 0.67, at the ratio of 0.80 the tensile strength was approximately 48% higher compared to 0.67. Analysis of fracture patterns revealed that at the curvature ratio of 0.80, the fracture mode shifted to an unstable and disturbed pattern, characterized by secondary shear cracks and the irregular propagation of the main crack.
