This research describes the goals, design and implementation of a quasi natural gradient, laboratory scale, SAND tank (aquifer) model experiment. The model was used to study the transport of an inorganic tracer (Chloride) in groundwater, within a tropical aquifer (porous medium) material. Three-dimensional SAND tank (1.8 m × 0.3 m × 0.8 m) experiments were conducted to investigate contaminant transport and natural attenuation within the SAND tank. In all, 360 samples were collected during 24 sampling sessions, for the three days of the tracer experiments in the SAND Tank. The OWENA SAND is a poorly graded SAND with 88.1 % SAND and 11.9 % gravel. Geotechnical properties including; coefficient of uniformity Cu = 2.53, coefficient of gradation Cz = 0.181, hydraulic conductivity K = 5.76 x 10-4 m/s, bulk density ρ = 1.9 Mg/m3, effective porosity ne = 0.215 and median grain diameter D50 = 0.55 mm, were determined. Other relevant hydraulic and solute transport parameters, such as dispersion coefficients and dispersivities were also established for the tropical soil.

In this research, the phenomenon of stress relaxation in unreinforced and reinforced SANDy soil with geotextile layer has been studied using a large-scale direct shear test. To investigate the effect of shear speed and soil density on the amount of resistance loss due to stress relaxation, two shear speeds of 0.5 and 5 mm/min and two relative densities of 35% and 60%, respectively, loose and medium density, have been used. All samples have been tested in direct shear test under vertical stress of 100 kPa. The results show that the amount of resistance loss due to stress relaxation depends on the shear stress level, soil density, presence of a geotextile layer in the soil and shear speed. In such a way that by increasing the level of shear stress and shear speed and by decreasing the density of SAND and also with the presence of a geotextile layer in soil, the amount of resistance loss due to stress relaxation increases.

Preparation of uniform and repeatable reconstituted SAND specimens of required density is a prerequisite for obtaining reliable results from experimental studies. Among different methods of reconstituted specimens, SAND pluviation technique is widely adopted by researchers because of its unique advantage. In this study, a new curtain traveling rainer (CTR) is developed for large model SAND bed preparation in experimental studies. CTR is a simple and low-cost system which is worked on the principle of air pluviation of SAND. It provides specimens with wide range of relative density of SAND bed (viz, 30%-90%) and very high degree of spatial uniformity of density distribution while reducing the time of preparation the specimens. A series of laboratory tests is carried out in order to study the performance of the proposed system and the effect of...

The phenomenon of liquefaction in loose and saturated SANDy soils is one of the most important hazards for engineering structures during an earthquake. In this phenomenon, the SAND changes its behavior rapidly from solid to viscous fluid, resulting in the instability of the ground. In this research, at first, SAND samples with liquefaction history collected from a site in Dorood, Lorestan, Iran. Samples obtained from depth of 1.8-2.7 and 2.7-3.5 m and in the laboratory, the parameters of maximum density, moisture content, friction angle and cohesion were determined. Then, in order to evaluate the effect of additive on the liquefaction potential, different percentages of clay from Dorood region added to the samples and tested. Finally, three-dimensional finite difference software (FLAC3D) used with inducing Dorood earthquake, to investigate liquefaction potential of stabilized samples by analyzing the u/σ ratio for models. The results showed that adding clay to the soil of this area reduce the friction angle, increase cohesion, and has a favorable effect on the liquefaction potential. Results of this investigation indicated that adding 3% clay to the liquefied Dorood SAND, would lead to decrease the liquefaction potential up to 39%.

The phenomenon of liquefaction in loose and saturated SANDy soils is one of the most important hazards for engineering structures during an earthquake. In this phenomenon, the SAND changes its behavior rapidly from solid to viscous fluid, resulting in the instability of the ground. In this research, at first, SAND samples with liquefaction history collected from a site in Dorood, Lorestan, Iran. Samples obtained from depth of 1. 8-2. 7 and 2. 7-3. 5 m and in the laboratory, the parameters of maximum density, moisture content, friction angle and cohesion were determined. Then, in order to evaluate the effect of additive on the liquefaction potential, different percentages of clay from Dorood region added to the samples and tested. Finally, three-dimensional finite difference software (FLAC3D) used with inducing Dorood earthquake, to investigate liquefaction potential of stabilized samples by analyzing the u/σ ratio for models. The results showed that adding clay to the soil of this area reduce the friction angle, increase cohesion, and has a favorable effect on the liquefaction potential. Results of this investigation indicated that adding 3% clay to the liquefied Dorood SAND, would lead to decrease the liquefaction potential up to 39%

Band e Rig Kashan is one the few large SAND zones of Iran with various SAND forms which is located at the south of salt lake. The area under study is a part of Band e Rig Kashan at south west of Maranjab with an area of 1.272 km2. In this study, thirty typical SAND hills were selected. The research method, based on field visits and sampling of SANDs in front head, tail, right and left arms of the understudy SAND hills was performed in the two time periods of August and March 2008, and by the use of grading technique, SAND particles were classified and their abundance were verified and analyzed.The aim of this research was review and study of seasonal changes of SAND particles diameter and their impact on the geometrical shape of SAND hills. The findings show that due to changes of direction, speed and frequency of wind during a year, changes occur on diameter afflection of SAND hills in main parts of SAND hill which leads to the changes of geometrical shape of forehead and right and left arms of SAND hill.

One of the ways to improve the performance of simple solar stills is to use energy storage materials to store energy during the day and use it at night. Several energy storage materials have been studied by researchers, one of which is the use of SAND. In this research, the improvement of a simple solar still performance has been studied using SAND with different grain size distribution inside its basin. For this purpose, four solar still were made in Esfarayen (latitude 36. 20 and longitude 57. 67), Iran, and the effect of SAND grain size distribution on its performance was studied in four treatments. The height of SAND and water was 10 cm and the average grain size of treatments was considered 6. 9, 2. 8, 1. 1 and 0. 7 mm. The experiments were performed for 4 days in mid-August 2020. The results showed that the SAND-containing treatment with an average grain size of 2. 8 mm had better productivity and thermal efficiency than other cases where the average grain size of the used SAND was larger or smaller. Therefore, grain size distribution of the SAND seems to affect the performance of simple solar stills and there is an optimal amount for grain size.

Aeolian sediments are in 6 percent of land and 97 percent of them are in arid land. On average, about 20 percent of the arid regions of the world are covered by these. Prevailing winds can shift SAND dunes and affect their accumulation. According to sediments have damage and harmful effects on the living then study of this subject is significant importance. In this research with Fryberger method and used of WR PLOT 7. 0 and MATLAB 2013 software in order to assessment of wind regime as well as used from anemometer data of five station near Kashan ERG. Results indicate that east-west winds are dominant and each station shows a kind of wind regime. The frequency of calm winds increases respectively in station of Jngalbani (32. 77), Qom (40. 05), Garmsar (44. 83), Ardestan (50. 15) and Kashan (77. 04). After calm winds in the area, the most of class is 11-7 Knot, while the most effective class is 17-11 knots (992. 6 Erode Index) for wind erosion in the region. Jangalbani station with 441. 81 VU and kashan station with 40. 02 VU are the highest and lowest quantity of SAND drift potential in the region. Comparative studies on various stations in the world according to SAND drift potential in the area indicated that kashan ERG is not hazardous then in general, could say that it located in the low-middle class. And the formed of linear and transverse dunes near Kashan and Jangalbani station following a global trend. Result show taht there is note full compliance beatwen F ryberger method and SAND Rosr Graph 3. 0 software.