This paper presents the results of laboratory experiments on the effect of matric suction on the compressibility of unsaturated gypsum sand soil under various types of loading. The soil samples were obtained from Al-Najaf city in Iraq with gypsum contents of 14 %, 22 % and 29 %. A wetting-process tests were conducted in a modified triaxial cell on these soil. This procedure likes when a structure has been constructed and the degree of saturation of a foundation soil is increased (decreasing in matric suction). Four matric suctions were adopted; 100, 60, 30 and zero percentages of initial matric suction under two different mean net stresses; 100 kPa and 200 kPa. The changes in the degree of saturation may be due to rainfall, water table rising and/or leaking of sewage and water pipes. The results from this path revealed that the volumetric strains are increased with decreasing of the matric suction and increasing of the gypsum content.

This study looks into the in uence of matric suction on the volume change of gypsum sand soil in unsaturated conditions. The specimens were collected from Al-Najaf, Iraq, and included 14-percent and 29-percent gypsum. Three series of initial stress of laboratory tests were utilized in a modi ed Oedometer device. For each gypsum content, twelve remolded specimens were examined in unsaturated circumstances with the initial stress and applied stress using four matric suctions (30 kPa, 18 kPa, 9 kPa and saturated state). Three tests were performed for each matric suction with initial stresses, no initial load, 56 kPa and 112 kPa, respectively. The ndings of unsaturated tests along the wetting path in terms of nal volumetric strain show a clear pattern of increasing in vertical strain as gypsum content rises and matric suction reduces under a variety of situations. The wetting process softens the gypsum components, resulting in an increase in vertical strains.

No abstract

This study looks into the influence of matric suction on the volume change of gypsum sand soil in unsaturated conditions. The specimens were collected from Al-Najaf, Iraq, and included 14-percent and 29-percent gypsum. Three series of initial stress of laboratory tests were utilized in a modified Oedometer device. For each gypsum content, twelve remolded specimens were examined in unsaturated circumstances with the initial stress and applied stress using four matric suctions (30 kPa, 18 kPa, 9 kPa and saturated state). Three tests were performed for each matric suction with initial stresses, no initial load, 56 kPa and 112 kPa, respectively. The findings of unsaturated tests along the wetting path in terms of final volumetric strain show a clear pattern of increasing in vertical strain as gypsum content rises and matric suction reduces under a variety of situations. The wetting process softens the gypsum components, resulting in an increase in vertical strains.

No abstract