Cone penetration at variable rates in kaolin–sand mixtures

Abstract

The degree of drainage that occurs during cone penetration is a crucial factor in the derivation of soil properties from cone penetration tests (CPTs). Fines content, especially clay fraction, has a significant effect on the soil's drainage characteristics as well as on its compressibility and strength. This paper presents the CPT results performed at variable penetration rates in a drum centrifuge and in a pressure chamber. The soils that are investigated are normally consolidated and comprise fine sand with varying proportions of kaolin clay (5, 10 and 25% by dry weight) as well as pure kaolin clay. A significant influence of kaolin content on CPT rate dependency is observed and this dependency is seen to be similar in both the centrifuge and pressure chamber experiments. A series of supplementary soil element tests using the Rowe cell and simple shear test apparatus is used to improve interpretation of the experimental results and investigate the suitability of a normalised velocity term to define the drainage conditions around penetrometers.

Analysis of CPT end resistance at variable penetration rates using the spherical cavity expansion method in normally consolidated soils

“…These involved a series of variable rate CPTs with a miniature piezocone (diameter = 10 mm) at a variety of penetration velocities in the laboratory pressure chambers, which were 400 mm in height with an inside diameter of 150 mm; a surcharge pressure was applied at the upper surface to maintain a constant vertical effective stress ðr 0 v0 Þ of about 55 kPa in the chamber. Suzuki and Lehane [33] demonstrates that the experimental results are comparable with previous centrifuge studies which employed much larger centrifuge strongboxes [5,6]; boundary effects are therefore likely to be relatively small. The soil domain was adjusted using the same mesh density to that shown in Fig.…”

Estudo do efeito de velocidade através do ensaio de piezocone realizado na argila mole de Sarapuí II

“…(1) sendo V = velocidade de penetração normalizada v = velocidade de penetração do piezocone D = diâmetro do piezocone ch= coeficiente de adensamento horizontal Finnie & Randolph (1994) primeiramente propuseram o uso da velocidade normalizada, onde o coeficiente de adensamento era cv, coeficiente de adensamento vertical, entretanto nenhuma referência foi feita ao nível de tensão considerado na análise realizada pelos autores. Outras sugestões em relação ao uso de cv apropriado: cv em um nível de tensão representativo, House et al (2001); na mesma razão de sobreadensamento, Suzuki & Lehane (2015). Quando o coeficiente de adensamento horizontal obtido por ensaio de piezocone é determinado, parece ser uma melhor escolha, portanto esse valor foi utilizado para a presente pesquisa.…”

The Optimisation Analysis of Sand-Clay Mixtures Stabilised with Xanthan Gum Biopolymers

“…The transition fines content is not unique and varies from soil to soil, ranging from 20 to 35% and mainly depending on clay type, sand grading, initial condition and stress condition [39,52]. In addition, the compressibility [52,57,58], permeability [39,41,59], the Atterberg limit [38,60] and cone penetration [61,62] of sand-clay mixtures have also been investigated.…”