GROUND IMPROVEMENT AND FOUNDATION DESIGN OF INDUSTRIAL FACILITIES ON LOESS SOIL

Abstract

This study addresses the exploration of two interchangeable foundation strategies for an industrial site (silo base) located in Silistra, Bulgaria. The geological conditions at the site present significant challenges due to the presence of local loess soil, which has been classified as "collapsible – Type II" in accordance with the Bulgarian Shallow Foundations Code, extending to a depth of 12 meters. To adhere to the code requirements and meet the stringent operational limitations imposed on the silos, including restrictions on foundation settlement and tilt, two potential approaches are considered. These options involve either mitigating the collapsibility of the soil or navigating through the collapsible soil using deep foundation techniques like piles, slurry walls, and similar methods. Following an initial technical analysis and cost estimation, this study favors the utilization of shallow foundation methods combined with local soil improvement practices. The first approach entails the construction of a dual mat foundation, which is placed atop a relatively thick base layer comprising a soil-cement mixture and soil that has been enhanced through rapid impact compaction (RIC). The second approach involves a mat foundation positioned on a relatively thinner base layer of soil-cement mixture, supplemented by strategically placed deep soil mix (DSM) columns. Both of these strategies ensure the structural reliability of the silos, advocate for the implementation of soil improvement methods readily accessible within the Bulgarian market, and offer a swift and cost-efficient execution.