Cone penetration test calibration for Erksak (Beaufort Sea) sand

Abstract

Interpretation of the cone penetration test in sands is generally based on empirical calibrations from tests in large-diameter calibration chambers. Although interpretation of these calibration data for clean sands in terms of the state parameter is expected to be broadly applicable to other sands, material-specific correlations are desirable for many projects. This paper describes a series of calibration chamber tests carried out on a sand dredged from the Beaufort Sea for construction of artificial islands. This Erksak sand is a uniformly graded, subrounded medium-grained sand with a fines content of 3–6%. The testing chamber described is 1.4 m in diameter, and allows independent control of vertical, horizontal, and back pressures on the sand sample. Samples of the sand were prepared by moist compaction to preserve the fines content, and then back pressure saturated.The chamber test data are presented and confirm that the Erksak sand fits the general trends observed for other sands very well. A method is also described that allows the interpretation to be consistent, even in the event that nonuniform void ratios occur in the samples. Measurements of horizontal stress behind the cone tip, which is a new development in cone penetrometer testing, are also presented. Key words: cone penetrometer, sands, in situ tests, state, calibration chamber, horizontal stress measurement.

Influence of placement method on the in situ density of hydraulic sand fills

“…They are more useful as relative indices of density than as absolute measures. Some results of chamber calibration tests on dense and very dense Erksak sand have recently been published (Been et al 1987) but these are not directly relevant to undensified hydraulic fills, which generally exist in a loose to medium dense state.…”

Critical State–Based Interpretation of the Monotonic Behavior of Hostun Sand

“…Manzari and Dafalias 1997;Ling and Yang 2006), as well as for the interpretation of site investigation data in sands (e.g. Been et al 1987;Konrad 1998). …”

Determining silt state from CPTu

“…Combining the void ratio of each calibration test with the appropriate CSL for that sand produced a relation between normalised CPT resistance Q and the initial state parameter y 0 (i.e. the soil state before pushing the CPT); Figure 11 shows an example of such a transformation of calibration chamber data for Erksak sand (data from Been et al, 1987a). The trends shown in Figure 11 can be fitted with an equation where Q p ¼ ðq t − p 0 Þ = p 0 0 and is the dimensionless CPT resistance (the subscript 'p' is used to denote the use of mean, not vertical, stress; the corresponding Q found in much of the in situ testing literature uses the vertical stress).…”

“…Bishop et al (1945) derived the limit pressure for expansion of spherical cavity in an infinite medium of Tresca material and suggested that the pressure required for a punch to indent metal to greater than three punch diameters was related to this cavity expansion limit pressure -this is the first statement of the idea represented by Equation 11. Gibson (1950) suggested that since Erksak sand (Been et al, 1987a) Figure 11. Normalised CPT resistance in calibration chamber test of Erksak sand the undrained strength of clay s c approximates a Tresca material, the Bishop et al (1945) result could be adapted for calculating the end bearing capacity of piles in clay by allowing for the additional shear force along the pile tip that acts in addition to the normal stress that is taken to be the spherical cavity limit pressure (P lim ).…”