ali raeesi estabragh

Electrokinetic technique is one of the common methods that can be used for removal of ‎organic contaminants in soil. There are some of organic contaminants with low solubility ‎in water. In order to improve the efficiency of remediation in this method it is possible to use appropriate ‎surfactants as flushing solution.‎ In this work SDS, Poloxamer 407 and Brij 35 surfactants were selected for improving the ‎remediation of a clay soil contaminated with Dimethyl phthalate (DMP). The contaminated ‎soil was prepared artificially with the concentration of 40 mg/kg in the laboratory. ‎Experimental tests were conducted in a special apparatus. It was consisted of a Plexiglas ‎with 1 cm thickness as the main cell. The main cell dimensions were 30 cm in length, 10 ‎cm in width and 30 cm in height. Two reservoirs as anode and cathode were added on ‎the two sides of the main cell and they were connected to the main cell. The prepared ‎contaminated soil after saturated was poured into the main cell of apparatus. The anode ‎and cathode reservoirs were filled with desired solution of surfactant and distilled water ‎respectively. A constant voltage of 50 V was applied to the soil for duration of 7 days for all tests. ‎A reference test was also conducted with distilled water in anode and cathode reservoirs ‎under the same voltage and duration. During each test the pH, EC (electrical ‎conductivity) and volume of outflow liquid discharge were measured. At the end of each test, ‎the shear strength of soil was measured by shear van at the distance of 4, 12, 19 and 26 ‎cm from anode. A number of soil samples were also extracted from these points for pH ‎measurement and removal of DMP by using GC (Gas Choromatography) ‎apparatus. The results showed that the shear strength of soil is increased with increasing ‎the distance from anode. The values of shear strength around the cathode were measured ‎as 7, 5.5, 8 and 42 kPa for distilled water and solutions of Brij 35, Poloxamer 407 and ‎SDS respectively. It was revealed that by increasing the distance from anode the value of ‎pH was also changed from acidic to alkaline. In addition, the results indicated that the ‎percentage of remediation at the distance of 4, 12, 19 and 26 cm from anode for solution ‎of SDS were 73, 70.5, 14 and 20.12 and for Brij 35 they were changed to 69.55, 66 ,21 ‎and 17 % respectively. The percentage of remediation for solution of Poloxamer 407 were ‎also determined 68.94, 65.89, 10.97 and -1.24 and for distilled water as 55, 53.3, 7.77 and -20 % at the ‎same distance from anode respectively. The results showed that the effectiveness of ‎solution surfactants in removal of DMP was SDS>Brij 35> Poloxamer ‎‎407.‎‎

The stabilization of a clay soil contaminated with glycerol was studied through a series of experimental tests. Contaminated soil was artificially prepared with percentages of 4,8 and 12% from the solution of glycerol with concentration of 50%. GGBS and activated GGBS with MgO or mixture of MgO and cement were used as agent materials. They were added and mixed with both natural and contaminated soil at percentages of 5,10 and 15%. Atterberg limits, compaction and unconfined strength tests (UCS) were performed on both soils with and without agents. The results showed that these parameters varied when adding glycerol or different agents and the extent of these changes were dependent on the percentage of glycerol and the type of agent. In addition, it was resulted that under constant conditions, strength values were dependent on the curing time. E50 (Elastic coefficient) for each strength test was calculated and the variations in its value corresponded to changes in strength. Comparing the results indicated that the effect of activated GGBS in increasing the strength and E50 of both soils were greater than that of GGBS alone. Based on the SEM results, it was revealed that the increase in the strength of stabilized soil is due to the production of chemical bonds between the particles of soil.

In this study, the improvement of a clay soil contaminated with MTBE (methyl tert-butyl ether) using magnesium oxide and hydrated lime was studied. Soil contaminated with MTBE was prepared in the laboratory, then mixed with different percentages of magnesium oxide and hydrated lime. Natural soil was also mixed with the same percentages used with the desired additives. Atterberg limits, compaction, Unconfined compressive strength, and SEM tests were performed on all samples. To determine the strength, the samples were prepared by static method and tested after 7, 14, and 28 days of curing time. The results showed that magnesium oxide and lime both increase the strength and E50 and thus improve natural and contaminated soil, which is a function of the percentage of used additives and curing time. The Comparison of improvement results showed that the final strength in natural soil is higher than in contaminated soil. In addition, the comparison of the results showed that lime has less effect on soil improvement compared to magnesium oxide. The SEM results also showed that the increase in strength is due to the cement materials produced during the carbonation process, which makes the particles paste to each other and make a rigid body.

In this research work, the remediation of a clay soil contaminated with dimethyl phthalate ‎was ‎studied by using electrokinetic method. Contaminated soil was made with the ratio ‎of 0.04 mg/g. ‎Non-ionic (Tween 80) surfactant and solution of 0.1 M NaOH were ‎used as anolyte. A reference ‎test was also considered with distilled water as ‎anolyte and catholyte. pH and EC and volume of ‎flow out fluid were measured ‎during the tests in both electrode reservoirs. At the end of each test ‎the shear ‎strength, pH, EC and degree of remediation of soil was measured at different ‎distance ‎from anode. The removal of contaminated was measure by a GC (Gas ‎Chromatography) apparatus. ‎The results showed that the amount of flow out fluid ‎for NaOH was nearly 20% more than the ‎solution of Tween 80 and distilled water. The ‎results also indicated that the strength of soil for ‎different solution is increased ‎by increasing the distance from anode. The value of it around the ‎cathode for ‎solution of NaOH was 14 kPa that was about 50 and 57% more than the distilled ‎water ‎and Tween 80. It was found that the degree of remediation at cathode is less than ‎anode. The ‎percentage of remediation for Tween 80 solution around the anode and ‎cathode were 53.88 and ‎‎16.5% respectively but for NaOH they changed to 50.82 and ‎‎23.26 near anode and cathode ‎reservoir. It was resulted that the effectiveness of NaOH ‎solution in remediation of soil was more ‎than the other used solutions.

In this research, the improvement of a clay soil contaminated with MTBE using GGBS activated by magnesium oxide and slaked lime was studied. Contaminated soil with MTBE was artificially prepared in the laboratory with a concentration of 2.25 g (MTBE)/kg (soil) and activated GGBS with slaked lime was added to it with different percentages. Experiments including Atterberg limit, compaction, uniaxial strength and SEM were conducted on samples of natural soil, contaminated and those which were mixed with the mentioned additives. The results showed that the used additives increase the strength of natural and contaminated soil and this improvement is a function of  percentage of the used materials and the curing time. In general, adding the used additives increases the strength by 14-22% by increasing the mixing percentage and curing time. In addition, the strength of natural soil with a same percentage of additives and the same processing time is about 3 to 7% higher than contaminated soil. Comparison of the effect of two additives clarified that lime has a greater effect in improving than activated GGBS. The SEM results also clarified that the hydration of the additives cause producing the cementitious materials which improves the mechanical behavior of the soil.

In this research work, the effect of cement, Ground Granulated Blast Furnace Slag (GGBS), and activated GGBS with MgO on the treatment of a clay soil was studied through conducting the experimental tests. The ratios of 1:3 was considered for making the mixtures GGBS: MgO. The used percentages of additives were 5, 10, and 15%. Various experimental tests such as Atterberg limits, standard compaction, compressive strength (UCS), and Scanning Electron Microscopy (SEM) tests were performed on the samples with different percentages of additives. Also, UCS tests were conducted on the compacted samples at curing times of 7, 14, and 28 days. The results of UCS indicated that all used additives are effective in improving the behaviors of soil, and their amount is dependent on the percentage of used additives and curing time. In addition, a comparison of the results showed that in a given percentage of additives and curing time, activated GGBS is more effective than GGBS alone in improving soil samples. Based on the SEM results, it was found that the increasing strength of stabilized soil is resulted from the interaction between soil particles and additives materials. An economical evaluation of soil improvement with used additives was also carried out and the best one was proposed for conducting in the field.

In this research work, the relationship between suction and swelling potential and swelling pressure of an expansive soil with different chemical pore fluid qualities was investigated through experimental tests. Different soils were prepared with different chemical qualities of pore fluid (distilled water, sodium chloride, and calcium chloride solutions with concentration of 250 g/l). The samples were made by the static compaction method for testing. Soil-Water characteristic curves were determined by the filter paper method for each prepared soil sample. By performing the swelling tests, the amount of free swelling and swelling pressure for different water content were obtained for each sample with different pore fluid. By using the Soil-Water characteristic curve of each sample, the equivalent suction was obtained for each water content. Then the curve of variations of free swelling and swelling pressure versus suction were obtained for each pore fluid. The results showed that the pore fluid with different qualities causes different Soil-Water characteristic curves. On the other hand, comparing the results showed that, at a given suction the swelling potential and swelling pressure of the samples with NaCl solution as a pore fluid was more than the samples with the pore of distilled water or CaCl2 solution. In addition, the SEM results revealed that the soil structure is dependent on the used pore fluid quality. Also, for a specific pore fluid, the soil structure is not the same at the beginning and end of the test.

In this work, the effect of MgO on the treatment of a natural and contaminated clay soil with phenanthrene was studied through conducting various experimental tests including Atterberg limits, standard compaction, uniaxial compressive strength (UCS), and SEM tests. The contaminated soil was prepared artificially in the lab. Natural and contaminated soil were mixed with 5, 10, 20, and 30% of MgO as an agent. The results showed that phenanthrene changes the structure of the soil and causes a reduction in Atterberg limits, wopt, UCS, and E50 of the soil. The results also indicated that the UCS and E50 of mixture natural and contaminated soil with different percentages of MgO are increased and the amount of increasing of them is dependent on the percentage of MgO and curing time. SEM results also showed that the formation of carbonation products due to hydration of MgO is effective in increasing the strength of treated soil samples.

Expansive soils are a very common cause of extreme damages because they are susceptible to volume change due to change in water content. Geotechnical problems associated with the expansive soils are well documented in different literature. As a result, a clear understanding of the behavior of such soils is required for effective design of structures and infrastructures on these soils. The effects of hydrocarbon pollutants as a flooding fluid on swelling potential of an expansive soil during wetting and drying cycles have not been considered in the previous researches. The aim of this research is to study the properties of an expansive soil with different flooding fluids, i.e. distilled water and solution of glycerol with 10 and 20% through a number of cycles of wetting and drying tests under constant surcharge pressure.

The soil that was used in this work was a highly expansive clay soil (according to the classification by McKeen (1992)). It was prepared by mixing 20% bentonite and 80% kaolin. This soil was classified as a clay with high plasticity according to the Unified Soil Classification System (USCS). The optimum water content in the standard compaction test was 18.11% and the maximum dry unit weight was 16.27 kN/m3.Distilled water and solution of glycerol with concentrations of 10 and 20% were used for flooding the samples. To prepare the glycerol solutions, the required amount of glycerol was mixed with distilled water.For making compacted samples for testing, the needed air dry soil was weighed and the required water was added to it to reach the desired water content (4% below the optimum water content according to the compaction curve). The soil and water were mixed by hand and then was kept in a plastic bag for 24 hours in order to allow the uniform distribution of moisture in soil. Samples were prepared by static compaction of the moist soil in a special mould.A conventional oedometer was modified to allow the wetting and drying tests to be conducted under controlled surcharge pressure and temperature. During wetting and drying, the vertical deformation of sample was measured by using a dial gauge. The variation of water content with void ratio during wetting and drying cycles was determined by using the information from the duplicated samples.

Fig. 1 shows the variations of vertical deformation during wetting and drying cycles for samples that were flooded with distilled water and solution of 10 and 20% glycerol. This figure illustrates that by increasing the number of cycles the amount of irreversible deformation is reduced until the equilibrium condition is achieved where the deformation due to wetting and drying is nearly the same. These results indicate that by increasing the concentration of glycerol the equilibrium condition with reversible deformation is reached in a fewer cycle of wetting and drying than the sample that was flooded with distilled water.Figure 1. Wetting and drying cycles for different quality of flooding fluids The results of void ratio versus water content at the equilibrium conditions for the samples flooded with distilled water and solution of 10 and 20% glycerol (that were obtained from duplicated samples) are shown in Fig. 2. This figure displays that the paths of drying-wetting for different flooding fluids are nearly S shaped curves. It is also seen in this figure that the order of the curves in this space is dependent on the percent of glycerol, the curves for the sample flooded with distilled water and 20% glycerol are located at the top and bottom the space of void ratio against water content.Figure 2. Water content- void ratio paths for different quality of flooding fluids The change in the thickness of diffuse double layer (DDL) affects on the swelling behavior of a soil.  The thickness of DDL is dependent on factors such as valency and concentration of cations, temperature and dielectric constant. The value of dielectric constant for water is 80 and for solution of 10 and 20% glycerol are 74.9 and 71.8, respectively. The magnitude of attractive and repulsive forces between clay particles are inversely and directly depended on the value of dielectric constant. The reduction in the value of dielectric constant causes an increase in the attractive forces and leads to the reduction in the thickness of DDL. When the flooding fluid is a solution of glycerol, the initial chemical composition of pore fluid in the sample is changed. The chemical composition of pore fluid has different effects on the structure of clay soil such as changing in the thickness of DDL. When the flooding fluid is distilled water the pore fluid of samples has a dielectric constant of about 80. Therefore, the values of attractive and repulsive forces are not changed because of the same dielectric constant of flooding fluid and pore fluid. The results of tests on these samples (flooded with distilled water) show that by repeating the wetting and drying cycles the potential of swelling is reduced and after several cycles a reversible equilibrium condition is attained as depicted in Fig.1. When the pore fluid is solution of glycerol, the attractive forces are increased due to the reduction of dielectric constant of pore fluid and causes reduction in the thickness of DDL. The shrinking of DDL causes formation of flocculated structure in the soil and results in pasting of particles together leading to the reduction potential of swelling. When the concentration of glycerol is increased the dielectric constant is decreased, the magnitude of attractive forces is increased and the degree of flocculation of the soil structure is increased that is yielded to reduction of swelling potential.

Effect of different flooding fluids on the properties of an expansive soil during wetting and drying cycles were studied. The following conclusions can be drawn from the present research:-After a number of wetting and drying cycles, the observed irreversible deformation were diminished and equilibrium was achieved. Solution of glycerol causes more reduction in the potential of swelling than distilled water.The wetting and drying paths in the space of void ratio and water content are S–shaped curves. The variation in the void ratio of samples flooded with solution of glycerol is smaller than distilled water.

In this research, laboratory studies were carried out to improve a clay soil by adding calcium ion through Electrokinetic method Experiments were performed in a special device using distilled water firstly, as the reference test and calcium chloride solution with the concentration of 0.25, 0.5, 1 and 1.5 molar secondly, as an anode reservoir fluid under the influence of 52-volt voltage during 7 days. During the experiment, the pH value was measured for electrolyte at the anode and cathode reservoir. Also, volume of water discharged from the cathode reservoir was measured at a given time interval. After the tests, shear strength of the soil was measured at different distances from the anode. The results showed that the calcium injection into the soil increases shear strength of the soil, and its amount depends on the concentration of calcium chloride solution, so shear strength increases by increasing concentration of the calcium chloride solution.

Contaminants can be categorized into organic and inorganic groups. Organic contaminants are carbon based, and their presence in waste forms may be as a single contaminant associated with inorganic contaminants, or a suite of complex mixtures which may be toxic at very low concentrations. Organics of greatest environmental concern are usually refined petroleum products, chlorinated and non-chlorinated solvents, manufactured biocides, organic sledges and substances from manufacturing processes. Most contamination due to organics are associated with accidental spills and leaks, originating from equipment cleaning, maintenance, storage tanks, residue from used containers and outdated material (Yong and Mulligan, 2004). Transport and fate of organic contaminants are important. Organic contamination migrations are due to advection (by fluid flow through soil) and diffusion, but other forms of transport e.g. infiltration may also contribute to migration (Environment Agency, 2002). The response of the soil to a contaminant depends upon the type of soil and the nature of the contaminant. The sensitivity of soil to contaminants depends upon the type of soil (such as particle size, mineral structure, bonding characteristics between particles and ion exchange capacity) and the nature of contaminants. Fang (1997) defined a sensitivity index (ranging from 0 to 1) to different types of soil. Sensitivity of sand and gravel (0.01 to 0.1) is much lower than clay particles (0.6-0.9). There are a number of techniques for remediation of contaminated land. These include physical (washing, flushing, thermal, vacuum extraction, solvent extraction), chemical (stabilization and solidification) and bioremediation techniques. However, the applicability and feasibility of different methods for remediation are dependent on many factors such as soil characteristics (soil type, degree of compaction and saturation), site geology, depth of contamination, extent of contaminant in lateral direction, topography, surface and ground water and the type and amount of contaminants. Thermal treatment and using surfactants are the most popular methods for remediating the soil contaminated with petroleum compounds. In this research remediation of a soil contaminated with different percentages of gasoline was studied through physical techniques in laboratory. The applied physical techniques were thermal technique and use of two different kinds of surfactants. The obtained results were compared with each other and discussion was performed.
Material and Soil, gasoline and surfactant are the basic materials that were used in this work. The soil that was used in this testing program was a clayey soil. Two different types of ionic and nonionic surfactant, namely Tween 80 and SDS, were used in this work for remediating soil, contaminated with gasoline. Contaminated soil was prepared by adding 5 and 10 % weight (to air dried soil) of gasoline. 6 kg air dried soil was selected and the desired amount of gasoline was weighted, then it was sprayed on the soil and thoroughly mixed by hand for about 2 hours. The prepared mixture was kept inside a covered container for a week in order to come to equilibrium with the soil. For thermal remediation the contaminated soil with a specific percent of gasoline was kept inside a constant convection oven at 50, 100, and 150oC for about one week to desorb the contaminating compound. Tween 80 and SDS were used for remediation of the contaminated soil. The amount of used Tween 80 was 25% weight of contaminating compound and selection of SDS amount was based on 50% weight of contaminating matter. The samples for the main tests were prepared by static compaction according to the optimum water content and maximum dry unit weight that were obtained from standard compaction tests. Atterberg limits, grain size distribution, compaction and unconfined compression tests were performed on samples of natural, contaminated and remediated soil according to the ASTM standard.
The results of Atterberg limits (LL, PL and PI) for the contaminated soil (with 5 and 10 % gasoline) indicated that the values of them are increased with increasing the percent of gasoline. These values are nearly the same as natural soil after remediation with thermal method and surfactants. The grain size distribution curves were determined for the natural soil, contaminated soil with 5% and10% gasoline and soil remediated by thermal and surfactant techniques. The results showed that by using thermal technique the percent of clay is decreased and the percent of sand and particularly silt is increased by increasing temperature. The results of grain size distribution for the soils remediated by SDS and Tween 80 showed that the percent of clay is reduced but the percent of silt and sand are increased. Comparing the results of the two surfactants shows that the effect of Tween 80 in reduction of the percent of clay is more than SDS. The results showed that after thermal treatment, the maximum dry unit weight decreases and the optimum water content increases. For the contaminated soil with gasoline a reduction in maximum dry unit weight is observed compared with natural soil. The effect of SDS and Tween 80 on soil remediation is reduction in maximum dry unit weight and optimum water content. The results of compression strength showed that adding gasoline to soil causes a reduction in final strength and this reduction is a function of gasoline percent. The results also indicated that the strength of remediated soil by thermal or surfactant techniques, is reached nearly to the strength of natural soil. Scanning electron microscopy (SEM) tests were performed on the samples in order to observe the microstructure of the samples in different conditions (natural and contaminated with different percent of gasoline). The results of SEM showed that the structure of soil is changed by contamination to gasoline. It can be said that the gasoline causes reduction in the thickness of DDL because of low dielectric constant and hence a flocculated structure is formed. In the flocculated structure due to attractive forces, the fine particles paste to each other and form coarse particles. Therefore, variations in the Atterberg limits and compaction parameters can be resulted from forming new structure by adding gasoline. These results of compression strength are not in agreement with the theory of diffuse double layer (DDL). The reduction in dielectric constant would cause a flocculated structure in soil and the strength of the contaminated soil should be increased in comparison with the natural soil. It can be said the viscosity of gasoline cause reduction in the strength of contaminated soil.
In this experimental work a cohesive soil was contaminated with 5% and 10% of gasoline. The experimental tests showed that the properties of contaminated soil are different from natural soil and the change in the properties is a function of gasoline percent. The contaminated soil, was remediated by thermal treatment and also using two surfactants. The results also showed that using surfactants is more effective than using thermal method in soil remediation, and can treat the soil nearly to its original condition.
-Base on the SEM analysis results, adding gasoline to the soil, will change the soil micro structure to a flocculated one.
-The gradation curves show that adding gasoline to the soil will change the gradation from finer to coarser.
- Contamination to gasoline will change the compaction parameters of the soil, and will reduce the soil final strength significantly.
- The results show that using thermal method and surfactants is effective in remediating the soil, but it is more effective to use surfactants.

Piping is an erosive process that occurs in hydraulic structures under the influence of upward seepage. Lack of sufficient notice of this phenomenon may seriously affect the stability of hydraulic structures. In this research work the effect of reinforcement soil on the variations of critical hydraulic gradient and seepage force were investigated through experimental tests. Reinforcement of samples was performed by two geo grids with mesh diameters of 6mm (No.1) and 2mm (No.2). One dimensional piping test were carried out on non-reinforced vs. reinforced sandy soil samples, compacted and fabricated through static methods, and in a specially designed apparatus. The results indicated that the critical hydraulic gradient and resistance against seepage force increased by reinforcement of the samples and that the resistance is a function of the number of the geogrid sheets as well as their location. In addition, the results indicated that the effect of the two geo grids is nearly the same for treatment of the soil against piping.

Soil pollution by hydrocarbon is a significant Geo-Environmental problem that can affect the environmental quality of soil, groundwater and air. Soil can be contaminated by organic materials attributable to leakage from underground or aboveground storage tanks and accidental spills. The response of soil to the contaminants not only depends on the local environment but it is also influenced by factors such as particle size, bonding characteristics among particles, and ion exchange capacity. The transport of contaminant components from soil into groundwater can cause serious problems. The use of contaminated soil and its stabilization can be considered in earthworks such as embankments, backfills, and roads if there is no pathway for leaching of contaminants to underground water or if the contaminants pose no risk to the public and the environment. In some areas the native soil is contaminated with hydrocarbon substances. For performing projects in such areas, because of the haulage distance to suitable soil and economic considerations, often the use of local soil is dictated for construction. Thus, the treatment and stabilization of local soil must be considered. On the other hand, in some areas where the soil has been contaminated and the treatment is not economic, for the design of a project in these areas the effect of the contaminating substance on the soil behavior should be evaluated. Therefore, understanding the mechanical behavior of contaminated soils and their treatment is important. Improving the mechanical behavior of clay soils by stabilization is a means of fulfilling geotechnical design criteria.
An investigation into the behavior of a contaminated clay soil with Anthracene and its treatment was carried out through a program of experimental tests.. Anthracene is a representative of one group of hydrocarbon, which are called PAHs (Poly Aromatic Hydrocarbons). PAHs create due to incomplete combustion of fossil fuels or wastes.
In order to investigate the effect of cement on the stabilization of clay contaminated soil with Anthracene, the specimens of natural clay soil, contaminated soil with Anthracene, soil-cement and Anthracene-contaminated that is stabilized with different percentage of cement (5, 10, 15 and 20%) in different curing times (3, 7, 14 and 28 days) was prepared by static compaction method at maximum dry density and optimum moisture. Atterberg limits and Unconfined compressive strength (UCS) tests were conducted on the specimens. The results of the experimental work showed that adding Anthracene to clay soil, change the compaction parameters, for example, the dry specific weight of soil is reduced and the optimum water content is increased. Although, adding cement to the Anthracene-contaminated soil, improves the compaction of soil, it increases the dry specific weight and reduced the optimum water content. In addition, adding the Anthracene also is changed the unconfined compressive strength of soil, it reduces strength of soil. Although, adding cement is incresed the strength of the contaminated soil. The amount of increase in the strength is depended on the percent of cement and curing. The results showed that Atterberg limits are increased by adding Anthracene to the clay soil, but are reduced by adding Anthracene or cement or adding Anthracene to soil-cement. The results indicated that adding the Anthracene to the soil, changes its structure to flocculated shape, but the decreasing of friction between soil particles due to adding Anthracene, led the soil particles to move easily together. By the way, the results of this research showed that the cement could stabilize contaminated soil with Antracene.

In this research variation of moisture and volume of an unsaturated silty soil were investigated under different suctions through experimental tests in triaxial apparatus special for unsaturated soils. The tests were carried on specimens of silty soil that made by slurry method in modified triaxial cell (triaxial cell with doubled rings) under 5 suctions from 0 to 300 kPa. Applying the target suction have been done by axis translation technic and loading the specimen under constant suction was carried by using increment loading. The results show that preconsolidation pressure will increase by increasing suction. Furthermore according to the obtained results, creation of yielding curve (LC) in space of stress- suction is possible. Also investigation of variation in slope and intercept of normal compression line showed that variation of volume and moisture of soil is function of suction changes.

In this research the mechanical behavior of an expansive soil (with different pore fluid) was investigated under the constant and variable temperature through experimental tests. The soil samples with different pore fluid (distilled water, NaCl and CaCl2 with concentration of 250 gr/Lit) were prepared by static compaction method. Experimental testes were conducted in two modified odometer under 10 KPa surcharge pressure at constant and variable temperature. The axial deformation of samples were determined during each test. The results showed that equilibrium condition is achieved nearly after 5 cycles. The reduction of swelling potential at equilibrium condition for sample with distilled water as pore fluid is more than samples with NaCl and CaCl2 solutions. In addition comparing the results for samples with NaCl and CaCl2 solution in variable and constant temperature indicated that reduction of swelling potential is not the same.

In this research, in order to develop new relationships with reasonable accuracy for estimation of the ýsubmerged hydraulic jump characteristics, a study has been conducted experimentally. Experiments have ýbeen done in a rectangular channel with a length of 9 m, a width of 0.5 m and a depth of 0.45 m. Froude ýnumbers in these tests range from 3.5 to 11.5 and between submergence ratios of 0.1 to 4. According to the results, the water surfaces profiles have been obtained in different Froude numbers and submergence ýratios. Also, some relationships with high accuracy to estimate such characteristics as jump length, ýsubmerged depth on the gate, and the relative energy loss have been developed. The results also showed ýthat, in a given Froude number, length and relative energy loss for submerged hydraulic jump are, respectively, more and less than those for free hydraulic jumps. In addition, for submerged hydraulic jump, ýat a given Froude number, by increasing the submergence ratio, the jump length and submergence depth on the gate increases and relative energy loss decreases. Finally, using sensitivity analysis technique, the ýeffectiveness of dominant parameters on the developed expressions on the changes in submergence depth ýon the gate parameters and relative energy loss has been determined.

In this research the effect of randomly reinforced soil and soil cement with different percent of cement and fiber and different length of fiber was investigated. Samples were prepared according to the maximum dry unit weight and optimum water content due to the corresponding compaction curves. Compressive and tensile strength were conducted on samples for different curing times. Regression equations were proposed based on the experimental data for prediction of the compressive and tensile strength of reinforced soil and soil cement. Comparison between the model predictions and the experimental results showed that the proposed model can predict the mechanical behavior of reinforced soil and soil cement satisfactory.

In this work, remediation of a contaminated clay soil with gasoline was studied through experimental tests by thermal and washing methods. A natural clay soil was contaminated artificially by different percent of (5% and 10%) gasoline. The contaminated soil was remitted at different temperatures (50, 100 and 1500 C). In addition, washing method was conducted on contaminated samples by using two kinds of surfactants (SDS and Tween 80). Experimental tests were including gradation, Atterberg limits, compaction and uniaxial compression tests which were performed on samples of natural, contaminated and remediation soil. Experimental results showed that adding gasoline to natural soil cause changes in physical and mechanical properties of soil and these changes are functions of gasoline percent. The results also showed that both thermal and washing techniques are effective in remediation of soil particularly for soil contaminated with 5% gasoline but the effect of them, and particularly surfactants, is reduced by increasing the percent of gasoline.

Clay soils characteristics are completely changed in the exposure of the organic pollution, and the soil behavior determination is completely affected by some parameters such as organic pollutant type and stress history. Therefore, the soil consolidation characteristics of two kinds of clay soil with low and high plasticity have been studied. The soil samples were prepared from slurry method and slurry samples were compressed under a pre-defined load to represent the effect of stress history and different concentrations (10, 25, and 40%) of glycerol and ethanol. The results represent that the compression index (Cc) increases with increasing the concentration of the pore fluid under the slurry conditions. However, compression index decreases in samples with stress history. Although the pre-consolidation pressure increases with increasing the pollutant concentration in the low plasticity soil, the same factor is not significantly affected by pollutant concentration in the high plasticity soil. In other words, the variation of compression index is dependent on the type of the soil and the chemical composition of pore fluid.

There are many techniques for the remediation of contaminated soil. One of these methods is electrokinetics. The electrokinetics technique is comprised of three major processes such as: electro-osmosis، electro osmosis and electrolysis. Electropheresis is referred to the process that causes the movement of colloid sized particles under an electrical field within the soil moisture. Electro-osmosis is the process of movement soil moisture from anode to cathode. The electrolysis is only due to the movement of ions and ion complexes in soil. The electrokinetics method is recognized as an effective technique in remediation of metal contaminated soils. Recently researchers showed that showed that it is possible to use this technique to remove a range of water soluble organic contaminates from soil. A review of the literature shows that the treatment of soils contaminated with MTBE has not beenstudied. Therefore،the aim of this work is to investigate the remediation of a soil contaminated with MTBE using the electrokinetic method

Expansive soils can be found in many parts of the world particularly in arid and semi-arid regions. These soils pose a significant hazard to civil engineering structures due to its high swelling and shrinkage potential. This paper presents the results of an experimental program developed to investigate the effect of cyclic drying and wetting on the swelling potential of expansive soils with various pore water qualities. Soil samples were prepared by static compaction with distilled and saline pore water solutions consisting of sodium chloride (NaCl) with 50 and 250 g/L concentrations. Soil samples were subjected to drying and wetting cycles using a modified oedometer apparatus, under a surcharge pressure of 10 kPa. Axial deformations caused by drying and wetting during various cycles were measured until shrink-swell equilibrium condition was attained. The results indicated that conducting consecutive drying and wetting causes a considerable reduction in the swelling potential of soil samples prepared with different qualities of pore water. Shrink-swell equilibrium in soil samples prepared with distilled water and 50 g/L NaCl solution was achieved after 5 consecutive cycles while soil samples with 250 g/L NaCl solution as pore water, reached equilibrium condition after approximately 3 or 4 cycles. Furthermore, the overall swelling potential for soil samples prepared with 250 g/L NaCl solution was seen to be greater compared to distilled water and 50 g/L NaCl solution respectively.

Expansive soils are found in many parts of the world particularly in arid and semi-arid regions. They are considered a worldwide problem as they cause extensive damage to civil engineering structures. As a result، a clear understanding of the behavior of such soils is required for the effective design of structures and infrastructures on these soils. Researchers have demonstrated various methods to reduce expansive soils swelling potential، with one being soil treatment. In this paper an experimental program was developed to study the treatment of an expansive soil using mechanical and chemical techniques. Two different types of artificial fiber consisting of polyethylene (bar shaped) with a diameter of 0. 3mm and polypropylene (tape shaped) with a width of 3mm were used in order to randomly reinforce soil samples with various fiber contents of 0. 5%، 1% and 1. 5%; and fiber lengths of 10، 20 and 30mm. Chemical treatment was carried on using lime and cement as soil stabilizers with various percentages of 5%، 8% and 10%; for curing times of immediate، 3 and 7 days. Uniform and repeatable moist-compacted soil samples were prepared by static compaction at a chosen moisture content and dry density less than the optimum water content and maximum dry density from standard proctor compaction tests. Free swelling and swelling pressure tests were conducted using a one-dimensional oedometer apparatus. In addition multiple regression equations with 3 and 2 independent variables were developed based on experimental results. The proposed multiple regression equations present an understanding of the variation of free swelling and swelling pressure as a function of swelling time، fiber or chemical stabilizer content and fiber aspect ratio (fiber length divided to fibers diameter or width) or curing time for various values. Experimental results and statistical analysis indicated that soil treatment with artificial fibers and chemical stabilizers can indeed reduce swelling potential in expansive soils. Reduction of free swelling and swelling pressure in samples randomly reinforced with artificial fiber was seen to be dependent on fiber content، fiber length and fiber shape، where tape shaped fibers showed more reduction in free swelling and swelling pressure thus being more effective compare to bar shaped fibers. Furthermore reduction of free swelling in samples treated with chemical stabilizers were seen to be a function of percentage of chemical stabilizer and curing time with cement showing to be more effective compare to lime. In addition chemical stabilizers proved to be more effective in reducing soils swelling potential compare to artificial fibers. The suggested regression equations can predict and estimate the free swelling curve، final free swelling and swelling pressure for various swelling time، fiber or chemical stabilizer content and fiber aspect ratio or chemical stabilizer curing time with accuracy and a high degree of agreement between experimental and predicted values. Also، the regression equations can aid the performance of a sensitivity analysis which indicates the importance of each independent variable (fiber or chemical stabilizer content، fiber aspect ratio or chemical stabilizer curing time) in estimating final free swelling and swelling pressure.

Expansive soils are considered a worldwide problem as they cause extensive damage to civil engineering structures. An important characteristic of expansive soils is their susceptibility to volume change due to wetting and drying. This paper presets the effect of pore water quality on the swelling and shrinkage behavior of an expansive soil during wetting and drying cycles. 33 soil samples were prepared by static compaction with various pore water qualities consisting of distilled water، sodium chloride (50g/lit) and calcium chloride (250gr/lit). Wetting and drying cycles were conducted on samples in a modified odometer apparatus under the surcharge pressure of 10 kPa using distilled water as the reservoir fluid during wetting. Results indicated that samples prepared with calcium chloride show more swelling potential compared to distilled water and sodium chloride. Furthermore swelling and shrinkage potential، specific volume and dry unit weight for soil samples reach equilibrium after 5 cycles for distilled water and sodium chloride and 3 cycles for calcium chloride.

Soil-cement has been used widely as a base material for constructing many projects، such as pavement of highways and lining of channels and reservoirs. This paper presents the effect of an organic contaminant (Glycerol) on the mechanical behavior and properties of soil and soil-cement mixtures. Soil samples were prepared by static compaction at maximum dry density and optimum moisture content for various percentages of cement and Glycerol and various curing durations. Results indicated that contaminated soil with Glycerol (3%، 6% and 9%) show lower compressive strength compare to natural soil. Furthermore the decrease in compressive strength is seen to be a function of Glycerol percentage. In addition the use of cement (3% and 6%) on natural soil will cause increase in compressive strength، furthermore the increase in the compressive strength of different soil-cement samples were seen to be a function of cement percentages and curing duration. In addition soil-cement mixtures contaminated with 3% of Glycerol show greater compressive strength compare to uncontaminated soil-cement mixture، however the use of higher percentages of Glycerol (6% and 9%) resulted in a noticeable decrease in strength compared to uncontaminated soil-cement mixtures.

Nowadays، application of Electro osmosis to remove water out of the soil is one of the most efficient methods of fine soil improvement. The electric field created by electrodes placed in the soil، cause water molecules move and get extracted from the porous media. In this research، an electro-osmosis system assembled as vertical drains was applied in a laboratory scale، for treatment and improvement of fine soil. For the purpose some saturated clay samples were prepared and placed in the designed physical model and tested. The results showed that using electro osmosis to withdraw water from the soil the quantity of water will be more and the extraction done more quickly. Also an increase in the difference of voltage between cathode and anode will increase the volume of water leaving the soil. Measurement of electrical conductivity (EC) and pH length wise in the soil showed that in electro osmotic process، pH will increase around the cathode and decrease at the anode. while EC being increased at either the cathode or anode. Also it was observed that the applied voltage to the soil sample decreases from anode to the cathode. Then it is concluded that the electro osmotic method can be a suitable alternative for soil settlement instead of surcharge being applied.