---

In this research, the Integrated Noise Model (INM), has been calibrated to perform the noise pollution evaluation in the vicinity of Mehrabad International Airport (MIA). First a conceptual model was developed to analyze the compatibility of airport noise with the land use based on the most widely accepted noise pollution standards. Second, the data generated from the INM package was compared with real data acquired from the test stations positioned around airport. Finally, the outputs of the calibrated model was compared with the noise pollution standards. The results show that more than 70 percent of the land use in the vicinity of airport are not compatible with the accepted noise levels. The generated noise contours was superimposed on the digital map of the city and the areas which violated the permitted levels was recognized. Moreover, the more noise sensitive facilities such as hospitals, schools, and residential units can be positioned in areas which have the permitted noise levels. The model and the procedure can be used to design new airports. Noise evaluation of existing operational airports can be performed by the model developed in this research.

---

Landslides are major natural hazards which not only result in the loss of human life but also cause economic burden on the society. Therefore, it is essential to develop suitable models to evaluate the susceptibility of slope failures and their zonations. This paper scientifically assesses various methods of landslide susceptibility zonation in GIS environment. A comparative study of Weights of Evidence (WOE), Analytical Hierarchy Process (AHP), Artificial Neural Network (ANN), and Generalized Linear Regression (GLR) procedures for landslide susceptibility zonation is presented. Controlling factors such as lithology, landuse, slope angle, slope aspect, curvature, distance to fault, and distance to drainage were considered as explanatory variables. Data of 151 sample points of observed landslides in Mazandaran Province, Iran, were used to train and test the approaches. Small scale maps (1:1,000,000) were used in this study. The estimated accuracy ranges from 80 to 88 percent. It is then inferred that the application of WOE in rating maps’ categories and ANN to weight effective factors result in the maximum accuracy.

---

Hydrologic Evaluation of Landfill Performance (HELP) model is one of the most accepted tools to simulate

the hydrological attributes of landfills. Although some major deviations from real values has been reported about the

calculated results for leachate generation by HELP model but other researchers and/or engineers in practice have

used it in some places to estimate amount of leachate produced in the landfills. On the Other hand this model is

elaborated and mainly used in developed countries with the waste having low moisture content and also in climatic

conditions with high precipitation. This research investigated the applicability of the model in arid areas, by

construction of two 30m× 50m (effective horizontal length) test cells in Kahrizak landfill (longitude=51°, 20',

latitude= 35° 27' degrees), and monitoring the real leachate generation from each one. A set of field capacity and

saturated water conductivity tests were also performed to determine basic hydrologic properties of municipal waste

landfilled. A comparison was made between values calculated by HELP model and recorded values, shows that a

prediction of leachate on annual basis can be done by HELP model with acceptable accuracy but when the infiltration

of water to waste body increases due to leachate production, the model intents to underestimate water storage capacity

of the landfill, which lead to deviation of calculated values from real ones.

---

The main task in the design and construction of impermeable liners in landfills is to block the migration of pollutants to the groundwater

systems or to reduce its rate to a reasonable amount. That is why environmental regulations force governments to construct engineered

waste dumps for waste management purposes. These liners are exposed to various types of chemical, biological, and physical processes

and are affected by the leachate which is produced from decomposition of waste materials accompanying methane gas. The leachate

includes a lot of components such as water and different types of salts. For this reason, the geotechnical characteristics of clay liners

which are evaluated in laboratories using distilled water or tap water might be far different from the representative sample of the in-situ

conditions. There are some evidences regarding the effect of these salts on the physical and mechanical properties of clay barriers which

could affect the long-term performance of these liners. Since the main criterion for impermeable bottom liners in landfills is their

hydraulics conductivity, the increase of this parameter could have a considerable environmental impact. This paper embraces the results

of a recent study on the effect of three inorganic salts, NaCl, CaCl2 and MgCl2 on some geotechnical properties of a common used clay

soil in impermeable bottom barrier in Kahrizak landfill, the main waste disposal center of the Tehran Metropolitan. Also the effect of

bentonite content by adding different percentage of this special clay mineral, 10 and 20 percent, on these properties was investigated.

Laboratory tests like liquid limit, compaction, 1D consolidation and free swell tests were performed for this purpose. Results indicated

that all of these salts could have a considerable effect on the geotechnical properties of the mixtures. The main reason of such effects is

the changes which occur in diffuse double layer of clay particles.

---

Portland cement can be mixed with sand to improve its mechanical characteristics. Many studies are reported in literature on this topic, but the effect of principal stress rotation has not been investigated yet. Considering the inherent anisotropy of most sands, it is not clear whether the added cement shall contribute to equal increase in strength and stiffness at vertical and horizontal directions or not. Furthermore, it is not well understood how the cement as an additive in non-compacted (loose) sand compared to compacted (dense) sand without cement, contribute to improving the material behavior in undrained condition such as limiting the deformations and the liquefaction potential. In this research, undrained triaxial and simple shear tests under different stress paths are carried out on different mixtures of Portland cement (by adding 1.5, 3 and 5 percent) with clean sand to investigate the effect of principal stress rotations. The triaxial test results revealed that the cement mixture reduces the anisotropy, while it improves the mixture mechanical properties compared to compacted sand without cement. The results of the simple shear tests validated the triaxial test results and further clarified the effect of the  parameter or rotation of principal stresses on the behavior of cemented sand mixtures.

---

The increase in the computational capabilities in the last decade has allowed numerical models to be widely used in the analysis, leading to a higher complexity in structural engineering. This is why simple models are nowadays essential because they provide easy and accessible understanding of fundamental aspects of the structural response. Accordingly, this article aims at showing the utility and effectiveness of a simple method (i.e. the Load Path Method) in the interpretation of the behaviour of masonry buildings subjected to foundation settlements due to landslide. Models useful for understanding brick-mortar interface behaviour as well as the global one are reported. The global proposed approach is also validated by using Bi-directional Evolutionary Structural Optimization method. Moreover, drawing inspiration from a case study, the article shows that the proposed approach is useful for the diagnosis of crack patterns of masonry structures subjected to landslide movements.

---

Municipal Solid Waste (MSW) materials are among the most complicated materials for geotechnical engineering as their composition includes an organic fraction, which suffers loss of mass over time, and a fibrous part, which acts as reinforcement, governing the MSW shear behavior. Because of these characteristics MSW can be described as a viscous material which shows time dependent behavior. Since the decomposition of MSW leads to gas and leachate generation, the changes in the MSW’s mechanical behavior could be linked to gas emission and leachate production from landfills. This paper deals with the characteristics of MSW materials to provide the necessary data for efficient and safe landfill design, construction and operation. The MSW physical characteristics such as composition, water content and organic content at varying ages, field and laboratory measurements of methane generation and leachate production, MSW compressibility behavior and its shear strength are covered. By presenting these data the authors hope to promote a better understanding of the mechanical behavior of MSW and provide useful data for use in landfill management tasks.

---

This research shows the results of studies carried out to define and analyze the effect of aging on MSW behavior of Kahrizak Landfill, the biggest landfill in Iran. Studied samples consisted of fresh samples and also aged ones with 5.5, 14 and 21 years of age which were obtained by mechanical excavators in aged burial locations. Analyzing variation in MSW components illustrates that paste fraction of MSW decreases due to aging process while fibers show a rising trend. Also the moisture content and the organic content of MSW reduce below half of the initial values while the degree of decomposition (DOD) increase up to almost 60% after 14 years. These variations over the time are significantly related to the burying methods and environmental condition of burying location. Shear strength behavior of MSW material was analyzed by some CU tests using large scale triaxial apparatus (D=150mm, H=300mm) on remolded MSW specimens. General observations depict that with an increase in strain level, loading rises without any peak point on stress-strain curves. Fresh samples represent the lowest shear strength followed by 21, 14 and 5.5 year-old samples respectively. There is a direct relationship between fiber content and shear strength. Internal friction angle of aged samples decreases in comparison with fresh ones while cohesion has an inverse trend and rises over the time. According to the effect of burying condition on MSW characteristics, it seems that DOD factor is a more appropriate factor than age in order to analyze long-term behavior of MSW.

---

Due to the existence of fibrous materials such as plastic fragments, the strength anisotropy of Municipal Solid Waste

(MSW) materials is the main source of differences between their mechanical response in direct shear and triaxial apparatus.

As an extension of earlier research on the mechanical behavior of MSW using a large traixail apparatus, results presented in

Shariatmadari et al. [1] and Karimpour-Fard et al. [2], the current study was programmed and executed. MSW samples were

tested using a computer controlled large shear box apparatus with normal stress levels ranging between 20 to 200 kPa. The

effect of fiber content, fiber orientation, aging and shearing rate on the response of MSW were addressed. The results showed

that shear strength of MSW increases with normal stress, although, in spite of the presence of reinforcement elements in MSW

and unlike the results from triaxial tests, no strain hardening could be observed in their mechanical response. An increase in

the shear strength of MSW was observed with increasing the shearing rate. Increasing the shearing rate from 0.8 to 19

mm/min, enhanced the shear strength of samples from 16 to 27% depending on the shear displacement level. Although, the

same trend was investigated in traixial tests, but lower rate-sensitivity in the mechanical response of MSW in direct shear tests

were observed.

Unlike the results of triaxial tests with aging process, mobilized shear strength level of MSW samples tested under direct

shearing decreased comparing fresh samples. It was also observed that altering the fiber content and their orientation could

affect the mechanical response and shear strength of the MSW. Additionally, there is an optimum fiber angle in MSW which

yields the highest level of shearing strength.

---

The physical properties of the municipal solid waste (MSW) in Kahrizak Landfill (Tehran, Iran) and its changes due to aging were investigated in this research. A study of the components of the fresh MSW in this landfill showed that more than 60% of it was made from the wastes of foods, fruits, vegetables and organic materials. Next to that, paper/cardboard and plastics, with contributions of 14% and 11%, comprised the greatest parts of the waste materials. Meanwhile, the results obtained from these studies revealed that the contribution of the organic part has been decreased during the last two decade by about 20% while the plastics and paper/cardboard contribution has been increased by the same amount. In order to investigate the effect of aging on the physical properties of MSW, waste samples of 5.5, 14 and 21 years of age were obtained by excavating the aged waste burial regions of this landfill. A study of the changes in the composition of waste materials through aging also revealed that the portion of paste was decreased from 25% to 40% due to the decomposition process, while the contribution of plastics and fabrics was increased up to 200%. Particle size became finer with the mean size being reduced from 70 mm in the fresh wastes to 20 mm in 21-year-old wastes due to the decomposition process. The moisture content of the fresh waste samples was reported to be more than 150%, which was considerably larger than that of other existing landfills. Along with the increase in the age of the waste samples, the moisture content was decreased by as much as one third of the initial value. Furthermore, since the waste mass became more homogeneous by age, the variation of the moisture content was reduced. The organic content of the 14-year-old waste was found to be 20%, which was less than 0.3 of the initial value. Moreover, the variation of the organic content in the waste samples was directly related to the moisture content of the samples with both parameters being reduced to less than one third of the initial value in the older samples. Investigation of the moisture content and the organic content of the aged samples showed that the burial location had a significant effect on the trend of variations. The average density of the fresh waste was measured to be 3.5 and 7.3 kN/m3 after production and burial, respectively. It was found that the average density of the fresh waste grew to about 12kN/m3 as the age was increased.

---

Complete recognition of calcareous sediments engineering behavior considering their local expansion and wide variety of engineering properties is very important. In south parts of Iran, there are some carbonate hydrocarbon reservoirs which are covered by calcareous deposits. Hormuz Island in is one of the most strategic areas in Hormuz Strait between Persian Gulf and Oman Sea. In this study, a series of undrained monotonic and cyclic simple shear tests was performed on saturated Hormuz calcareous sand specimens using hollow cylinder torsional apparatus. The tests were carried out on specimens with various relative densities under different effective consolidation stresses. Based on the results, pore pressure generation, shear strain development, stress-strain characteristics of the specimens are presented and compared with the technical literature. In addition, dissipation of strain-based energy during the cyclic loading and its relation to excess pore water pressure is described. The cyclic resistance curves of specimens with different initial conditions are plotted. Also the results of monotonic and cyclic tests are compared together for better interpretation of Hormuz calcareous sand under undrained torsional loading.

---

Pedestrians are among one of the most vulnerable road users. Speed of vehicles is considered as one of the major causes of danger for pedestrians crossing the street (making cross movements). Therefore, it is of utmost importance to devise suitable solutions for reducing speed of vehicles. One of these solutions is installation of Pedestrian Refuge Islands (PRI) in very wide midblocks. With regard to fluctuations in pedestrian and vehicle traffic volume in traffic hours, there are different variations in collisions between vehicle and pedestrian. In this article the effect of constructed PRI in Tehran on speed of vehicles and consequently their effects on probability fluctuations of fatal accidents are determined. Speed of vehicles in two phases of before and after arriving to the PRI is assessed. Additionally, speed of vehicles in non-observed volumes of vehicle and pedestrian are calculated using Aimsun.v6 simulation software. Paired T-test is applied to compare average speed of vehicles before and after the PRI. The results revealed that except for traffic volumes of 3000-4000 veh/h and 400-600 ped/h in other volumes reduction of average speed of vehicles as a result of PRI is significant. Also, the results show that in all volumes, these equipments reduce the probability of fatal accidents to under 10%. According to the results, it is recommended that PRI should be installed in midblocks where traffic volume of vehicles in each lane is less than 750 veh/h.