The Collapse of Foundations in Khon Kaen Soil and the Rehabilitation by Means of Composite Piles

Loess is found in many places in Northeast Thailand including Khon Kaen Province. It is generally considered as a soil with good engineering parameters. However the collapse of loess was found in many construction projects due to an increase in its moisture content. This paper presents some research results which show the strong effect of moisture content on loess behavior. An increase in moisture content caused the loess internal friction angle to decrease. Furthermore, an increase in moisture content caused large settlements of footings founded on the loess. A case study is presented herein. The water supply pipe in front of a three-story building founded on spread footings in Khon Kaen University was broken. The loess supporting the foundation at the middle part of the building was soaked for many days and then the foundation severely settled. Some reinforced concrete structures were damaged. An underpinning technique was employed for the rehabilitation. So-called composite piles were installed for transferring the load from the building to a laterite layer overlain by the loess layer. The rehabilitated building became serviceable again.