Abstract

The expansive nature of soils containing high amounts of montmorillonite mineral can be altered through chemical stabilization, resulting in a material suitable for construction purposes. In this paper, the physicochemical behaviour of phosphoric acid treated samples was studied using X-ray Diffractometry (XRD), Energy Dispersive X-ray Spectrometry (EDAX), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), and Solid-State Nuclear Magnetic Resonance spectroscopy (SS-NMR). It was found that in acid stabilized montmorillonitic soil, clay alumina was more susceptible to dissolution and mostly responsible for the formation of aluminate phosphate hydrate compounds that bonded the soil particles together. Furthermore, since the action of stabilizer was mainly “surface-associated”, the efficiency of phosphoric acid treatment in terms of strength improvement was rather limited.

Earthquake induced liquefaction in saturated granular soils is an important phenomenon which has been under intensive investigation in the past three decades. In coastal areas, despite the fact that top layers of clay and silt deposit have proper static and dynamic strength properties, appreciable amount of settlements have been observed during earthquakes. The investigations conducted in these fields have shown that the major cause of these destructions is the liquefaction of thin discontinuous layers of sand, which are known as sand lenses. In this paper, the liquefied behavior of three loose and saturated sand lenses embedded inside a clay deposit have been modeled by using the FDM method. Finally the impact of sand lens effective zone on the settlement of surrounding soils were investigated. The results indicated that by doubling the ratio of sand lens distance to its length and hence reaching its effective zone, each sand lens behaves independently of other lenses buried in the clay deposit.