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.
Model tests on single and groups of stone columns with different geosynthetic reinforcement arrangement
ABSTRACT: Stone columns have proved to be a useful technique for supporting flexible structures resting on soft soils. However, in the case of very soft soils, stone columns have encountered excessive settlements due to insufficient lateral resistance offered by the soft soil against bulging of the columns upon loading. The bulging may be reduced to a great extent by reinforcing the columns either by encasing them with geosynthetics or by placing horizontal circular discs of geosynthetics within the columns at a regular interval. In the present study, model tests have been carried out on long floating and end-bearing single and groups of columns with and without reinforcement to evaluate the relative improvement in the failure stress of the composite ground due to different types of reinforcement. The exhumed deformed column shapes were used to understand the failure mechanism for different types and configurations of reinforcement. The geogrid was the best geosynthetic type for encasement for end-bearing...
Geological, mineralogical and chemical characterization of Devonian kaolinite-bearing sediments for further applications in the ceramic (tiles) industry in La Paz, Bolivia
Clay minerals are widely distributed in Bolivia; among them, illitic clays are most common in the Altiplano where they are mined for use in the ceramic industry that has been growing in the last few years. In addition to illitic sediments, kaolinitic sediments have been recently discovered in sedimentary units in the Bolivian Altiplano. Residual ball clay occurrences in Devonian sedimentary units were studied as part of this work. Geological mapping and geophysical studies (ERT and GPR) were done for better understanding the origin of the deposits and were part of a preliminary study of the mineral potential to define the relationship with the host rock. Chemical and mineralogical techniques such as X-Ray Diffraction, Scanning Electron Microscopy and Inductively Coupled Plasma analyses were performed in samples from the studied area to verify the presence of kaolinite. Atterberg limits and behaviour of the raw material in ceramic specimens supported by chemical analyses show that this material is suitable for manufacturing tile ceramics. This study provides fundamental knowledge for deposit exploitation and future generation of an alternative source of employment for the inhabitants of Micaya.