Zainal Abdul Kareem Esmat - Assis. Prof., Civil Engineering. Engineering College-Baghdad University
Amjad Ibrahim Fadhil - Ph.D. Student, Civil Engineering. Engineering College-Baghdad University, Ass. Lecture Uruk University-Baghdad

The bearing capacity of soils and its prediction is a subject that is practicedevery day. Shallow foundations are usually constructed on unsaturated soilswhere the soil strength may be higher compared to fully saturated soils dueto the contribution of the matric suction resulting from the reduction indegree of saturation. In this paper, the variation of the matric suction due tovariation in degree of saturation and the relative density of sandy soil isstudied through experimental tests that were carried out on four states ofsandy soil (Dr = 20%, Dr = 35%, Dr = 55%, and Dr = 75%). The resultsshow that the variation in relative density and degree of saturation causessignificant changes and important equations were proposed describing theseeffects on the matric suction, consequently, the variation of the matricsuction shown has a great effect on the shear strength of sandy soil.

Unsaturated soils, matric suction, relative density, degree of saturation, sandy soils