Skin Friction Degradation Due to Shrinkage of Expansive Soil

Abstract

This research discusses the loss of pile surface friction due to the contraction of the natural expansive soil found in Suranaree University of Technology, Nakhon Ratchasima. The research was tested on the surface friction of piles embedded in a mixture of expansive soil and clay found in large quantities in the same area. The soil sample is prepared with stand compaction method. The expansive soil used had a mixture ratio of 0, 50, and 100. The 16 mm diameter steel rod is pushed through the compacted soil sample to avoid end resistance to the steel rod. The soil is left to dry under ambient conditions. From the test results, it was found that the resistance at the pile surface decreased when soil water content was changing caused by soil shrinkage. Therefore, the correlation between surface resistance and pile subsidence was established as the modulus of pile-soil reaction of friction ( ). The vary with changing of soil water content for clay soil with swelling 50 %. In this research, the relationship between adhesion factor ( ) and water content in the soil was proposed, which could be used as a guideline for the design of piles in clay-swelling soils.