Study on the laboratory test of consolidation and shear strength of soft soils in the coastal delta in QuangNam – DaNang for planning and designing of transportation projects

Abstract

     This paper presents the results of study on the characteristics of soft soils in Quangnam - Danang coastal delta (consolidation and shear strength properties). It is clear that, the strata mainly include very soft clay, very soft sandy clay having different ages and origins (ambQ2 3 ; mbQ2 2 ; ambQ2 2 and abmQ2 1 ) which are Quarternary depositions, irreguarlly distributed with varying thicknesses, and almost not expose to the surface. These soft soils are under-consolidation with low pre-consolidated pressure (Pc = 52,55 kPa ÷61,5 kPa for very sandy clay and Pc = 45,50 kPa ÷ 58,8 kPa for very soft clay), high compressive ratio (a0,5-1 ≥ 10 kPa-1 ), horizontal consolidation ratio, which represent the heterogeneous characteristics of soft soils, small deformation modulus (E0,5-1 ≤ 5000 kPa) and low shear strength. The soft soils will cause severals problems in planning and designing work in general, especially for transportation engineering projects.