Fall-cone penetration and water content relationship of clays

Abstract

Results of previous studies on using the fall-cone test to determine the plastic limit of soils show that further research is warranted. The present investigation devotes itself to modification of the specimen preparation technique, examination of the relationship between depth of cone penetration and water content, and estimation of the plastic limit using the penetration depth against water content relationship. Specimen rings are made and used to replace the specimen cup so as to facilitate the preparation of specimens. Data of 26 soils, covering a wide range of liquid limits from 30% to 526%, show that the logarithm of depth of cone penetration against logarithm of water content relationship is linear. Therefore, a linear equation with two soil-dependent parameters is developed for estimation of the plastic limit. For a soil, the value of the soil-dependent parameters can be determined from as little as four fall-cone tests and substituted into the equation to estimate the plastic limit. The computed plastic limits of the soils analysed are within 0·8–1·2, with an average value of 1, times the measured plastic limits. The effects of strain rate and undrained strength ratio on the estimation of the plastic limit are evaluated and found to be limited.

Some Recent Developments in the Determination of the Atterberg Limits

“…Feng, 2000 andKoumoto &Houlsby, 2001) is also shown to be an acceptable way to describe fall cone data. If modeled in this way, a higher value of the slope increase is computed owing to the high curvature of the function close to the plastic limit.…”

“…Feng, 2000;Dolinar & Trauner, 2005;Lee & Freeman, 2009). Almost all of these researchers have assumed that the plastic limit is associated with a fixed strength (100 times that at w L ) and then used a strength test (e.g.…”

Use of fall cones to determine Atterberg limits: a review

“…Simply based on analysis of historical data, as the ratio of strengths at the PL and LL varies substantially between soils, these strength-based approaches can only coincidentally give correct PL values, actually measuring what might be termed the plastic strength limit (PL 100 ); that is the water content corresponding to s uFC ¼ 100 Â s uFC(LL) . Fall cone Belviso et al, 1985;Wasti, 1987;Harison, 1988;Feng, 2000Feng, , 2001Feng, , 2004Koumoto & Houlsby, 2001;Sharma & Bora, 2003;Lee & Freeman, 2009;Shimobe, 2010;Sivakumar et al, 2015), steady monotonic penetration (Stone & Phan, 1995;Stone & Kyambadde, 2007), fast-static loading (Sivakumar et al, 2009) and extrusion (Timár, 1974;Whyte, 1982;Medhat & Whyte, 1986;Kayabali & Tufenkci, 2010a, 2010bKayabali, 2011aKayabali, , 2011bKayabali, , 2012Kayabali et al, 2016) approaches for PL determination have all been suggested as alternatives to the standard thread-rolling approach. As mechanical tests, these strength-based approaches are seen by some researchers as means of achieving higher degrees of repeatability and reproducibility of results, although, to date, most fall-cone research has been conducted on well-behaved clay-rich soils that lie above the A-line on the standard plasticity chart.…”

“…w , PL) for water contents around PL 100 . This has implications for the preparation of the test specimens for fall-cone testing near the PL 100 Whyte, 1982;Wasti & Bezirci, 1986;Harison, 1988;Stone & Phan, 1995;Feng, 2000), in that for many cases sample preparation is difficult and some test specimens are likely not to be saturated, and calls into question the use of Hansbo's equation (1) for non-ductile materials. For PL 100 , PL, the strain-rate dependence and deformation mode of the soil test specimen will be significantly different for water contents between the PL 100 and the PL (i.e.…”

The Undrained Strength of Soft Clays Determined from Unconventional and Conventional Tests

“…Although it was originally developed to estimate the strength of remoulded cohesive soils, it became widely used as a standard method of determining the liquid limit of clays (Koumoto & Houlsby, 2001), having already been included in the British, Swedish, Canadian and Japanese standards (Claveveau-Mallet et al, 2012;Feng, 2000;Tanaka et al, 2012).…”