The effect of particle breakage on the dilatancy and shear behavior of marine calcareous and siliceous deposits

A large part of ocean surface is covered by calcareous deposits. The Low stiffness and weak particles of calcareous soils deposited by marine organisms showed significant particle breakage under applied loads, which resulted in different behavior compared to terrigenous soils. A series of compression drained triaxial tests were carried out to evaluate the monotonic shear behavior of crushable and non-crushable soils. Three different soils, including Firoozkuh siliceous sand (as a non-crushable soil) and Hormuz and Bushehr calcareous sands (as crushable soils) which were different in mineralogy compositions were obtained from northern and southern Iran. The specimens were prepared in different relative densities (i.e., loose, medium and dense conditions) and consolidated under confining pressures ranging from 100 to 600 kPa. The monotonic shear and dilatancy behaviors of the soils have been presented in detail and the effect of particle breakage has been discussed. The results showed that particle breakage has a significant effect on the mobilized friction and dilatancy angles of marine crushable soils. There is a linear relationship between the amount of particle breakage occurring during a triaxial test and breakage angle. In addition, the mineralogical difference influences the breakage properties of calcareous deposits.