Numerical Analysis of Geosynthetic-Encased Stone Columns under Laterally Loads
Out of all methods for ground improvement, stone column became more popular these days due to its simple construction and economic consideration. Installation of stone column especially in loose fine graded soil causes increasing in load bearing capacity and settlement reduction. Encased granular stone columns (EGCs) are commonly subjected to vertical load. However, they may also be subjected to significant amount of shear loading. In this study, three-dimensional finite element (FE) analyses were conducted to estimate the shear load capacity of EGCs in sandy soil. Two types of different cases, stone column and geosynthetic encased stone column were studied at different normal pressures varying from 15 kPa to 75 kPa. Also, the effect of diameter in two cases was considered. A close agreement between the experimental and numerical curves of shear stress horizontal displacement trend line is observed. The obtained result showed that, by increasing the normal pressure and diameter of stone column, higher shear strength is mobilized by soil; however, in the case of encased stone column, increasing the diameter had more dominated effect in mobilized shear strength. Keywords—Ordinary stone column, validation, encased stone column, laterally load.
Settlement Behavior of Reinforced Embankments Supported by Encased Columns
Stone column supported embankments on soft clay deposits have some construction problems due to low bearing capacity, high compressibility and lack of lateral resistance. To overcome these difficulties, geosynthetics have been widely preferred by geotechnical engineers in recent years. This paper presents a two dimensional (2D) finite element model study, simulating a geosynthetic-reinforced (GR) and geosynthetic-encased stone column (GEC) supported embankment on soft soil. Numerical analyses are performed to investigate the effect of reinforcement and encasement on the vertical displacement of stone columns and soft soil. The results reveal a significant decrease in settlement with encasement, which is thought to be a direct consequence of the additional confining pressure produced by the geosynthetic encasement. With the help of base reinforcement, the surface settlement values of the soft soil reduced significantly.
Pioneer 10 Observations of the Ultraviolet Glow in the Vicinity of Jupiter
A two-channel ultraviolet photometer aboard Pioneer 10 has made several observations of the ultraviolet glow in the wavelength range from 170 to 1400 angstroms in the vicinity of Jupiter. Preliminary results indicate a Jovian hydrogen (1216 angstrom) glow with a brightness of about 1000 rayleighs and a helium (584 angstrom) glow with a brightness of about 10 to 20 rayleighs. In addition, Jupiter appears to have an extensive hydrogen torus surrounding it in the orbital plane of Io. The mean diameter of the torus is about equal to the diameter of the orbit of Io. Several observations of the Galilean satellites have also occurred but only a rather striking Io observation has been analyzed to date. If the observed Io glow is predominantly that of Lyman-α, the surface brightness is about 10,000 rayleighs.