SAMPLING DISTURBANCE EFFECTS IN RECONSTITUTED COASTAL SOILS

概要

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The effects of tube sampling disturbances on undrained shear properties of reconstituted samples of coastal soils were investigated. The values of undrained shear strength (s_u), initial tangent modulus (E_i) and secant modulus (E_<50>) were reduced while axial strain at peak deviator stress (ε_p) increased because of disturbance caused by the penetration of samplers. Disturbances also considerably reduced initial effective stress (δ'_i) and pore pressure changes. The changes in soil parameters between the "in-situ" and "tube" samples depended markedly on the characteristics of the tube samplers. Values of s_u, E_i, E_<50> and δ'_i decreased while the values of ε_p increased with increasing area ratio (or decreasing external diameter to thickness ratio) of the samplers. It was also found that the reductions in the values of s_u, ε_p, E_i, E_<50> and δ'_i increased with decreasing plasticity of the soils. A number of reconsolidation procedures, both isotropic and anisotropic including SHANSEP methods, were adopted in order to assess the suitability of reconsolidation of "tube" samples to recover the "in-situ" properties of the soils. It appeared that reconsolidation using SHANSEP procedures may not be applicable to these coastal soils. However, K_0-reconsolidation to "in-situ" stresses provided a better estimate of "in-situ" properties than other reconsolidation techniques.
社団法人地盤工学会の論文
2000-10-15