Original paper
Multi-blended granular columns encased with geosynthetics
Singh, Istuti; Sahu, Anil Kumar
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften Band 175 Heft 1 (2024), p. 73 - 88
64 references
published: Jun 25, 2024
published online: Mar 19, 2024
manuscript accepted: Jan 12, 2024
manuscript revision received: Jan 4, 2024
manuscript revision requested: Nov 3, 2023
manuscript received: Jul 11, 2023
ArtNo. ESP171017501005, Price: 29.00 €
Abstract
Land scarcity has prompted civil engineers to develop ground improvement techniques that enable construction, for instance, on grounds with expansive soils. Stone or granular columns inserted into the soft soil are frequently used for this purpose. In this study we investigate a ground improvement technique using multi-blended columns. Multi-blended columns contain a mix of industrial waste like fly ash, iron dust or stone dust in replacement of sand and cement as a binder. The continuously increasing volume of waste material makes it attractive for engineers to utilise such waste for construction purposes. In the present work we tried to utilise the waste in certain mixes and cast columns with these specific mixes in expansive soil. The parameters considered were the different blends of waste material in column design, different diameters of the single multi-blended column and bearing strength of single vs. groups of multi-blended columns. The experiments were conducted in the laboratory using a mould with a diameter of 15 cm and a height of 17 cm. Multi-blended granular columns using waste materials like fly ash, stone dust, iron dust, and cement as a binder were cast in moulds of 2, 3 and 5 cm diameter. The replacement technique was used for the installation of the columns in expansive soil. The column’s compressive strength was compared with and without the use of iron dust. The load-deformation curve was obtained with the help of a plunger of 5 cm in the CBR machine. The encasements were made from two types of geosynthetics, i.e. geogrid and geotextile. The mix design was followed by the UCS (unconfined compressive strength) tests performed on soil samples and the granular mix of different ratios with and without iron dust called as multi-blended columns. The mix used for the design of the multi-blended granular column showed optimum compressive strength compared to the expansive soil. The SEM and XRD analysis of the materials, i.e. soil, fly ash, stone dust, iron dust, and the mix used for the multi-blended column were done. The experimental results were validated with numerical modelling using Plaxis 3D. With the Plaxis software package, finite-element analyses (FEM) were also done utilising 10-noded triangular elements. For soft clay and column mix a draining analysis was performed using Mohr-Coulomb’s criterion. The numerical findings from the FEM were compared to the experimental results, and they were found to be in good agreement. There is no noticeable benefit when columns are spaced more than three times the diameter of the column. Design charts are created based on the findings, and a design procedure is offered.
Keywords
expansive soil • granular column • geosynthetics • waste materials • Plaxis 3D