Facilities built in areas affected by earthquake activity, such as tunnels, which have always been an integral part of human life, must withstand both dynamic and static loading. It has led to the need for practical studies on the effects of earthquakes on underground structures and the factors affecting their destruction. For this purpose, in this research, at first different patterns of tunnel’s excavation were investigated and by using Plaxis 2D software and based on Tabas earthquake in Iran, sensitivity analysis on Geotechnical parameters of the soil surrounding tunnel such as cohesion, friction angle, unit weight and modulus of elasticity was carried out, and the parameters whose changes have the greatest and least effects on the bending moment changes on the tunnel lining are introduced. The results show that tunnel excavation patterns significantly affect the bending moment, axial forces, displacements, and surface settlement of the tunnel. Often, by dividing tunnel excavation area to small parts, the values of bending moment, axial forces, displacements, and surface settlement of the tunnel decreases in static analysis. Also, outputs of sensitivity analysis on Geotechnical parameters of the soil surrounding tunnel showed that modulus of elasticity of the soil surrounding tunnel has the most effect and cohesion changes have the least effect on bending moment induced on tunnel lining..

Breakwaters are the important and the costly ones of the marine structures. Composite breakwater is one of the common types in the world. Because of the sensitivity of composite breakwaters to environmental conditions, also construction costs, difficulty of repair and maintenance and importance of equipments on and behind the breakwater, design of composite breakwater must be very accurate. Goal of present research is assessment of effect of environmental parameters in design of composite breakwater. In this way sensitivity of geometric parameters of this structure to hydraulic specifications such as period, height and direction of waves and depth of water, has been analyzed. Also effect of sea bed soil type in dimensions of this structure has been evaluated. Comparison between analytical and experimental formulas in evaluation of wave forces on composite breakwaters has been done. The results of this research have been expressed in some applied graphs for evaluation of effects of hydraulic and geotechnic parameters in dimensions of composite breakwaters. Thus results of present work can be used for attentively design of these structures in different environmental conditions of sea.

The pollution of soil and underground water with organic and toxic materials is a common environmental problem and oil is one of the most important of them. In the present study, consolidation behavior of clay contaminated with gas oil and kerosene has been investigated. The main objective was to determine the parameters associated with the value and rate of settlement of contaminated soil. Influence of various test parameters such as degree of contamination, contaminant type and density of samples were investigated on the consolidation behavior of kaolinite clay. Results show that by increasing the degree of contamination, Compressibility of soil increases while the consolidation coefficient and the permeability coefficient decrease.

Nowadays, the dispersion phenomenon is one of the main concerns for industrial and civil projects in southern regions of Iran. In this phenomenon, dispersive clay soil, under special situation, is dispersed and rapidly washed away. Due to the continuous developments in industrial and mineral additives, in this study metakaolin was used for soil improving dispersive soils. Researchers have always studied the use of additives for soil improvement. However, using cheap and environmentally friendly additives, such as natural pozzolans, are more desired. Natural pozzolans, are silica and alumina-silica materials with no apparent cement property but in presence of water, they make bonds with hydrate calcium and have cement properties. By reviewing previous studies, it can be seen that using pozzolanic materials are environmentally friendly, reduces energy consumption, reduces costs, reduces permeability and increases the chemical resistance of concrete. Metakaolin is a natural pozzolan with high permeability, with 50-55% SiO2 which reacts with Ca (OH)2 in room temperature and produces the calcium silicate hydrate (CSH) gel. Kolovos et al (2013) investigated mechanical properties of a soil improved by metakaolin. In this study, the optimum mix design of cement soil and its mechanical properties are investigated and the results show improved mechanical properties of soil. Wu et al (2016) studied the effect of metakaolin and cement on MHS strength and soil structure. The results show that adding metakaolin to soil reduces its sensitivity to water and significantly increased the uniaxial compressive strength and tensile strength of soil. Wianglor et al (2017) reviewed the effects of alkaline active metakaolin on compressive strength and particle structure of the improved mortar in 23 and 60 centigrade. The results show that increasing the amount of metakaolin and the temperature results in increased compressive strength and silicate and aluminate gel is apparently seen in mortar particle structure. In recent years, the compound effect of cement and metakaolin have rarely been studied, however there is no record for using metakaolin alone for soil improvement. This study aims to investigate the effects of different metakaolin percentages on reducing the clay dispersion potential, using crumb test, hydrometry, and also reviewing its Geotechnical properties, such as Atterberg limits, maximum dry density, optimum humidity percentage, uniaxial compressive strength, and its validation using SEM.

Nowadays, the dispersion phenomenon is one of the main concerns for industrial and civil projects in southern regions of Iran. In this phenomenon, dispersive clay soil, under special situation, is dispersed and rapidly washed away. Due to the continuous developments in industrial and mineral additives, in this study metakaolin was used for soil improving dispersive soils. Researchers have always studied the use of additives for soil improvement. However, using cheap and environmentally friendly additives, such as natural pozzolans, are more desired. Natural pozzolans, are silica and alumina-silica materials with no apparent cement property but in presence of water, they make bonds with hydrate calcium and have cement properties. By reviewing previous studies, it can be seen that using pozzolanic materials are environmentally friendly, reduces energy consumption, reduces costs, reduces permeability and increases the chemical resistance of concrete. Metakaolin is a natural pozzolan with high permeability, with 50-55% SiO2 which reacts with Ca (OH)2 in room temperature and produces the calcium silicate hydrate (CSH) gel. Kolovos et al (2013) investigated mechanical properties of a soil improved by metakaolin. In this study, the optimum mix design of cement soil and its mechanical properties are investigated and the results show improved mechanical properties of soil. Wu et al (2016) studied the effect of metakaolin and cement on MHS strength and soil structure. The results show that adding metakaolin to soil reduces its sensitivity to water and significantly increased the uniaxial compressive strength and tensile strength of soil. Wianglor et al (2017) reviewed the effects of alkaline active metakaolin on compressive strength and particle structure of the improved mortar in 23 and 60 centigrade. The results show that increasing the amount of metakaolin and the temperature results in increased compressive strength and silicate and aluminate gel is apparently seen in mortar particle structure. In recent years, the compound effect of cement and metakaolin have rarely been studied, however there is no record for using metakaolin alone for soil improvement. This study aims to investigate the effects of different metakaolin percentages on reducing the clay dispersion potential, using crumb test, hydrometry, and also reviewing its Geotechnical properties, such as Atterberg limits, maximum dry density, optimum humidity percentage, uniaxial compressive strength, and its validation using SEM.

The proposed classification based on the combination of geological variables and Geotechnical parameters provides the possibility of using geological knowledge in estimating the Geotechnical parameters. The city of Tehran is one of the metropolises that founded on Quaternary alluvium. The alluvium is divided into four groups, A, B, C, and D, based on age and formation conditions. Some researchers have proposed a new classification using the combination of geological variables and Geotechnical parameters for A and C Tehran's alluvia. The aim of this study is to sub-classification of unit B of Tehran alluvia based on combination of geological variables and Geotechnical parameters. In this research, based on geological findings in 66 locations of Tehran's alluvia, the geological variables affecting the Geotechnical parameters of the coarse-grained B alluvia including grain size, grain form, grain contact, cement between grain, homogeneity and layering were identified and based on these variables, unit B was divided into four units of Bn1, Bn2, Bn3 and Bn4. Using the results of 27 performed direct shear test and 70 plate loading tests in specified units, the Geotechnical parameters of these four units, including the internal friction angle, cohesion, and modulus of deformability were determined. With combination of geological variables and Geotechnical parameters, new classification of unite B was proposed that make it is possible to estimate the Geotechnical parameters based on the geological variables for this alluvium.

Shear wave velocity (Vs) is known as one of the fundamental material parameters which is useful in dynamic analysis. It is especially used to determine the dynamic shear modulus of the soil layers. Nowadays, several empirical equations have been presented to estimate the shear wave velocity based on the results from Standard Penetration Test (SPT) and soil type. Most of these equations result in different estimation of Vs for the same soils. In some cases a divergence of up to 100% has been reported. In the following study, having used the field study results of Urmia City and Artificial Neural Networks, a new correlation between Vs and several simple Geotechnical parameters (i.e. Modified SPT value number (N60), Effective overburden stress, percentage of passing from Sieve #200 (Fc), plastic modulus (PI) and mean grain size (d50)) is presented. Using sensitivity analysis it is been shown that the effect of PI in Vs prediction is more than that of N60 in over consolidated clays. It is also observed that Fc has a high influence on evaluation of shear wave velocity of silty soils.

Obtaining the soil shear strength parameters is necessary to know the site and at the same time costly and time-consuming. In this study, data from 129 Geotechnical boreholes in Kermanshah was collected and classified. Utilizing the group method of data handling (GMDH) and a variety of inputs, models were constructed. The correlation between shear strength parameters (friction angle and cohesion) with SPT-N and Geotechnical characteristics (such as fine particles and water content) was established. Predicted values for friction angle (RMSE=2.822) and cohesion (RMSE=4.161) were calculated with an approximation of ±20% and ±6 kilopascals, respectively. Comparisons with other researchers demonstrated the superior performance of the correlations, possibly attributed to variations in input parameters, the use of neural networks, and the focus on a specific study area. These correlations provide a valuable tool for estimating shear strength parameters in Kermanshah soil, enhancing their applicability in Geotechnical designs. The study suggests that incorporating non-linear relationships with multiple input parameters reduces correlation errors, and limiting the study area improves correlation performance due to sediment variations in each region. The use of the prediction models presented in this study can be useful depending on the circumstances, especially in cases where it is difficult to prepare a sample, or in the early stages of the project for initial evaluations.

Population growth and lack of space in some cities increased the need for public transportation and implementation of subway lines. One of the most important hazards in urban area tunneling is the possible effects of the settlement on the surface structures. In this research, the effect of the main Geotechnical parameters on the surface settlement has been studied. Literature show that simultaneous analysis of the parameters that affect tunnel behavior is not considered well. For this aim experimental design can be used because of its ability to make changes in input variables (Geotechnical parameters) and observe the output (settlement) changes. On the other side use the expert knowledge in a Rock Engineering System is useful in order to make judgment about complex systems. For this reason, this method was also applied in order to achieve research goal. A part of Karaj Metro tunnel Line was modeled by FLAC3D in order to use experimental design. Compare the simulation results with monitoring data indicates the efficiency of numerical model in condition like this. Next, a range and sensitivity analysis was performed by using the Taguchi method. Results show that E and ν, respectively has the highest and the lowest impact on the surface settlement. The output of the rock engineering system is also show that E and ν, respectively has the highest and lowest interaction with other parameters of the interaction matrix.