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Anchors play a special role in geotechnical structures such as excavations. The anchor section in soil is generally divided into five zones including reinforcement element, grout, grout and surrounding soil mixture, shear zone and soil media. The main objective of the present research is to determine the soil-anchor interaction parameters for numerical modeling of anchored wall using FLAC2D software. Basically, the injection area determining is the main challenge in the anchor force nomination. According to the proposed method, the diameter of the injected area is determined based on the injection pressure, grout volume, porosity and shear zone thickness. It is shown that the diameter of the injected area is approximately increased by 40% relatively to the drilling diameter. The diameter of the injected area in rock media, however, is equal to the drilling diameter. The other parameters are determined using equalization of rock media formulas for soil media. In order to ensure the validity of the proposed method, the pull-out test is numerically simulated in FLAC2D software. The numerical results have been then verified with anchor tension results in an excavation project. The results indicate that ultimate load of anchor calculated from the numerical model is comparable with equations proposed by many researches. Also, there is a negligible difference between the displacement obtained in numerical simulation and pull-out test results. This method is therefore can be used in numerical modeling of anchored wall in soil media with high precision. Anchors play a special role in geotechnical structures such as excavations. The anchor section in soil is generally divided into five zones including reinforcement element, grout, grout and surrounding soil mixture, shear zone and soil media. The main objective of the present research is to determine the soil-anchor interaction parameters for numerical modeling of anchored wall using FLAC2D software. Basically, the injection area determining is the main challenge in the anchor force nomination. According to the proposed method, the diameter of the injected area is determined based on the injection pressure, grout volume, porosity and shear zone thickness. It is shown that the diameter of the injected area is approximately increased by 40% relatively to the drilling diameter. The diameter of the injected area in rock media, however, is equal to the drilling diameter. The other parameters are determined using equalization of rock media formulas for soil media. In order to ensure the validity of the proposed method, the pull-out test is numerically simulated in FLAC2D software. The numerical results have been then verified with anchor tension results in an excavation project. The results indicate that ultimate load of anchor calculated from the numerical model is comparable with equations proposed by many researches. Also, there is a negligible difference between the displacement obtained in numerical simulation and pull-out test results. This method is therefore can be used in numerical modeling of anchored wall in soil media with high precision.

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Improvement of bearing capacity of existing foundations is of great significance. There exist many methods for practical purposes. Micropile is one of the most promising methods. Micropile is a replacement pile of small diameter (usually less than 300 millimeter) which is frequently reinforced using steel elements. To construct a micropile, steel reinforcement is placed in the borehole after drilling the borehole and subsequently the grout is injected into it. Micropiles transfer the structural loads to the deeper and stronger layers of the ground and confine settlement (similar to conventional pile foundations). They also improve the mechanical properties of soil layer such as density, bearing capacity, permeability and compressibility. Owing to their advantages, micropiles are widely used as foundations of new structures construction and also for reinforcing the foundation of existing structures. This research aims at experimental investigation of bearing capacity of foundations reinforced with micropiles under the condition of static loading. A small-scale physical model of a foundation reinforced with micropiles was developed and a series of static loading tests were carried out on. The model micropile-foundation was located on loose sand. Density of the underlying soil was kept almost uniform throughout the tests. The foundation model was circular and 100 mm and 5o mm in diameter and thickness, respectively. It was made from polyamide and considered to act as a rigid foundation during the loading owing to its material and thickness. This foundation was reinforced with a group of micropiles with 6 mm and 200 mm in diameter and length, respectively. These model micropiles were made from threaded steel bars. In order to mobilize friction, sand grains were glued to the surface of the micropiles. Various arrangements of micropiles including the number and inclination angle of micropiles were tested. From the comparative examination of the observed behavior of micropile foundations, the influence of micropiles’ arrangement on the mechanism and improvement of bearing capacity of foundation was investigated. Number of micropiles used in the group varied from 2 to 8. Micropiles were inclined at different angles (0°, 15°, 13°, 45° and 60°) to study its influence on the behavior of foundation reinforced with these elements. In order to quantitatively assess the degree of improvement in the bearing capacity of surface foundations reinforced with micropiles, an index R called “Network Index” was introduced in this study. The index R of unity means that the bearing capacity of foundations reinforced with micropiles is simply equal to the summation of the individual value of the surface foundation and that of the micropile group. There is an upward trend in the rate of index R when the number of micropiles is increased. On the other hand, in high numbers of micropiles used to reinforce the foundation, index R declines with increasing of inclination angle. In the case of micropiles with low-inclination-angle being implemented, bearing capacity is improved remarkably; an index R of 1.997 is achieved in this study where 8 micropiles inclined at an angle of 15° were used to reinforce the foundation.

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Physical modeling is one of the most applicable researching methods in Geotechnical Engineering. Physical models simulate Geotechnical Engineering phenomenon in small scale to evaluate the effect of different parameters on them. In geotechnical physical modeling, reaching to a targeted specific weight (γ) and Density Ratio (DR) for sand beds are important. Air pluviation is one of the most adoptable methods for preparation of uniform and repeatable sand beds of required density in physical modeling. In this method sand in a container falls from an opening bellow it through the air. With different openings, there are different types of air pluviation. It may consist of a single or multiple nozzles, single or multiple sieves or a narrow aperture that pours a sand curtain. A pluviator can be stationary or portable. Stationery pluviation is a traditional method that commonly used for preparing small samples. In this method the hopper is station and nozzle outlet is small and sand pours in a limit surface of sample, therefore uniformity of sand beds decreased. Also in the horizontal direction, stationary pluviation results in a great segregation in soils which contain fines. In a Travelling pluviator the hopper usually moves above the area of interest, in a certain pattern and the sand pours uniformly from nozzle or aperture in the sample or model box. This paper presents the details of a test series with a portable curtain rainer pluviator that has been developed for modeling the sand beds in model box in geotechnical laboratory in Ferdowsi University of Mashhad. The new portable sand pluviator has been designed and developed for preparation of sand beds in a box with large dimensions (1.8 m length, 0.4 m width, 0.8 heights). The main function of the pluviator was reproducing sand beds behind the wall in the model box. The apparatus consists of a hopper with a capacity about 20 kg which is placed on a rigid modular frame. The hopper frame is connected to a modular wheeled frame that could move back and forth longitudinally by a belt on a pair of rails. The modular frames could justify the height of sand fall during pluviation and keeps the sand fall height constant. The belt is connected to a series of gearwheels that moved by a stepping motor. The direction of motion is reversed automatically when certain steps of moving finished. The velocity of the hopper could be controlled in the range of 0.4 to 4 cm/s. The sand in the hopper exits from an aperture which is connected below the hopper and could be replaced. Different aperture widths used to change the deposition intensity. In these tests the Firoozkooh sand NO.161 used for calibration. The influence of different parameters such as Height of fall, sand flow Curtain velocity, sand curtain width and Sand deposition intensity (DI) evaluated on Relative Density (RD) of sand beds with obtaining several samples during calibration. As the results clearly shows, by increasing the velocity of container, decreasing the curtain thickness and increasing the height of fall, relative density will increase. The test results show the very good repeatability and uniformity in sand for physical models in a large domain of Relative densities (3% to 93%).