Discussion: Cone penetrometer and liquid limit

Abstract

Author's reply Dr Randolph's elegant, yet simple, analysis demonstrates the value of having closed-form solutions to engineering problems. Such solutions not only provide a check on corresponding solutions from numerical analyses, but also help to identify the dimensionless parameters which control behaviour. Hence, Dr Randolph has found that greater generality is achieved if one uses a stiffness ratio defined in terms of the rate of increase of skin friction k, rather than the rate of increase of soil modulus N,. The use of the latter definition is indeed appropriate when considering settlements in the elastic (working) range and can also be advantageous when cyclic degradation of skin friction is being incorporated into the analysis (Poulos, 198 1). There is little doubt that, although pile compressibility contributes to the length effect on skin friction, there are other factors which may also be significant, particularly strain-softening at the pileesoil interface. For example, model tests by Chandler & Martins (1982) indicate that reductions of up to 50% in the skin friction can occur following relatively large displacements. This effect would result in smaller values of the reduction rates i, than are indicated by the present analysis, and an analysis incorporating this strain-softening behaviour would give better overall agreement with the available data.

Use of fall cones to determine Atterberg limits: a review

“…Based on Schofield & Wroth (1968) and Wroth & Wood (1978) the strength gain factor R MW has been assumed as 100 by many researchers, but the authors' Figs 3 and 4 show this assumption to be false. A wide variation of R MW has been found by several other authors (Karlsson, 1961;Whyte, 1982;Wood, 1983;Wijeyakulasuriya, 1990;Brown & Downing, 2001;Nagaraj et al, 2012;Vardanega & Haigh, 2014).…”

Refinement of the Reverse Extrusion Test to Determine the Two Consistency Limits

“…Regarding a number of limitations of the Casagrande's cup method outlined above, many researchers proposed the use of the fall-cone method to determine the liquid limit (Sherwood and Ryley, 1970;Wood, 1982;Belviso et al, 1985;Wasti and Bezirci, 1986) and the same has been included in several national codes of practice such as British standars (BSI, 1990), Canadian standards (CAN/ BNQ, 1986) and Indian standards (ISI, 1985) (Prakash and Sridharan, 2006). In spite of the main advantages of fall-cone test such as simplicity, ease of operation and comparative reproducability, the American Society for Testing and Materials (ASTM), one of the worldwide used standards, has not included the fallcone method (Prakash and Sridharan, 2006).…”

Ters Ekstrüzyon Deneyi̇ni̇n İki̇ Kivam Li̇mi̇ti̇ni̇ Beli̇rlemek Üzere Yeni̇den Değerlendi̇ri̇lmesi̇

“…Yukarda işaret edildiği gibi, Casagrande tası metodunun bir çok sınırlamalarının bulunması nedeniyle birçok çalışmacı likit limitinin tespit edilmesi için düşen koni metodunun kullanılmasını önermektedir (Sherwood ve Ryley, 1970;Wood, 1982;Belviso vd., 1985;Wasti ve Bezirci, 1986). Aynı öneri İngiliz standartları (BSI, 1990), Kanada standartları (CAN/BNQ, 1986) ve Hindistan standartları (ISI, 1985) gibi bir çok ülkenin uygulama talimnamesinde de yer almıştır (Prakash ve Sridharan, 2006).…”