Effect of Coarse Aggregate Columns on Angle of Friction in Fine Sandy Soil

Abstract

Abstract: the study adopted samples from Tigris river shoulders ,which has been subjected to such collapses and cracks. After testing and investigation it was found the soil is formed from river deposits , which can be classified as fine sand soil . It is known that many of the collapses that occurs in the sides of rivers are due to the influence of shear forces . A different of diameters coarse aggregates columns and aggregates sizes used in this study are tested by direct shear test. The main objective of this research to increase the coefficient of friction between the soil particles in the test specimen by adding the coarse aggregate columns to the fine sand soil, In this regard the least void ratio was found as a beneficial index that relates with critical state of friction angle independent on soil gradation. The relations between critical state or high friction angles of the mixture with lower void ratio were determined as a function of addition pressure. The relationships could be useful to determination the strength parameters of (sand gravel mixtures).