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.
Consolidation of composite foundation improved by geosynthetic-encased stone columns
Abstract A theoretical solution is developed for calculating the consolidation of foundations reinforced by geosynthetic-encased stone columns (GESC). The elastic volumetric strains of the column and the surrounding soil previously obtained by the authors are adopted, and both the horizontal and vertical flows within the column and the soil are considered in this solution. The solution for calculating the consolidation of the type-column composite foundation without geosynthetics is obtained by degenerating the present solution to this special case and compared it with existing solutions. The comparisons show that, as underestimating the volumetric strains of the column and the surrounding soil, the average degree of consolidation calculated by the previous studies are greater than the present model and the differences are noted. Finally, the influence of geosynthetics on the consolidation of composite foundation is analyzed. The results show that the geosynthetics encasement has negligible effect on accelerating the consolidation of the composite foundation in the elastic phase.
Contractor Failure: Analysis
The possibility exists for any construction contractor to fail to filfill the contract requirements associated with a facility. Contractor failure occurs when a contractor is unable to perform his/her contractual duties, thus requiring the facility owner to invoke the contract's nonperformance clause. This paper provides aggregate contractor business failure statistics and outlines potential causes for failure. A framework to identify and quantify the associated costs is also introduced. Several case studies are presented to examine the cause and cost of failure and the means by which the facilities were completed. Alternatives available for project completion when contractor failure occurs are discussed. Recommendations to identify and monitor contractors at high risk for failure are outlined as well. This paper provides facility owners with a greater awareness of the possibility of contractor failure, how to quantify costs of contractor failure, and avoidance techniques.