Shear Wave Velocity (Vs) Anisotropy of Kaolinite and Fly Ash Kaolinite Mixtures Modified with Controlled Organics.

摘要

Anisotropy is an inherent property of soils. The anisotropy could either be induced by applied stress or inherent from particle eccentricity and preferential deposition. Other than stress and deposition, the anisotropy was also found resulted from the physicochemical environmental factors, such as pH, bulk fluid type and concentration. The investigations of the anisotropy behavior of clay particles have been carried out by researchers in the literature, however, the effect of organic agents and fly ash on the influence of the anisotropy property of clays still remains not well documented. Shear wave velocity transmitted by bender element was used to quantify the shear wave velocity (Vs) of the soil in three orthogonal directions, i.e., vh, hv, and hh. A floating wall consolidometer type bender element testing system was developed to study the anisotropic behavior of clay particles. The addition of fly ash and organic agents could largely affect the anisotropy property of kaolinite. Particle size analysis, zeta potential, and SEM tests were carried out to understand the micro fabric and Vs anisotropy. Salt treated kaolinite samples with different particle associations were thoroughly investigated. This research found that both salt and organic agents could induce micro fabric change of clay particles by charge neutralization and polymer bridging, thus influencing the anisotropy properties of the soil. Stress could also induce Vs anisotropy by changing the particle alignment. The addition of different amount of fly ash and organic types could induce Vs anisotropy in different directions. This research also supported that the cross-anisotropy was not true for kaolinite samples.