Settlement-Time Behavior of Steel Piles in Gypsifereous Sand- A Model Prototype Study

Abstract

There are a lot of studies conducted on gypseous soils dealing with the effect of collapsibility on the general behavior of the soil concerning its strength properties, settlement indexes, volume-mass relationship and permeability. To get rid of the bad soil properties then one goes into another subject as dealing with the aspects of soil improvement or replacement and the like. This study is devoted to settlement investigation of a small prototype pile erected into gypsifereous soil, loaded to 70% of its ultimate bearing load, socked for two hours and then leached with water for seven days. In preparing testing soil, well graded sand is mixed with pure gypsum in ratios of gypsum content of 10, 20, 30, 50, 70%. The loading frame is locally manufactured as to apply loads and to record settlement of pile. The results revealed that when gypsum is less than 10% or 20%, settlement recorded is small. The settlement-time curves show a convetional “S” shape in a semi-log scale. Maximum settlement obtained is for gypsum content of 70% and is about 30% of pile diameter. Finally, three additional socking and leaching tests are also conducted by using 5% concentration of CH3COOH (acid), grade-60 viscosity oil, and kerosene for specimens containing 50% of gypsum. Specimen socked and leached by oil shows very little settlement, while the specimen treated with kerosene shows less settlement as compared with water. The specimen treated with 5% concentration of CH3COOH shows 50% increase in settlement.