An Improved Model of Soil Response to Load, Unload and Re-Load Cycles in an Oedometer

Abstract

There are a number of advantages to be gained by representing the oedometric compression of a soil skeleton, during virgin loading, unloading and subsequent reloading by`log (v) versus log (p?)' relationships rather than the conventional`e versus log10 ( p?)' expression. The paper presents an augmented version of the basic, two parameter (C? c, C? s),`log (v) versus log (p?)' model in which the addition of two further parameters (C? r, C? o) enables a complete, nonlinear response for any load-unload-reload cycle to be reproduced. All four parameters, deduced from a single such cycle in an oedometer, can then be used to predict the response of the sample in any other unload-reload cycles. Results are presented from tests of this kind on a range ofˆne-grained soils to demonstrate the key attributes of the model. These include the generation of`log (mv) versus log (p?)' diagrams that furnish practically useful mv values applicable throughout any unload-reload cycle. The model also provides a simple means of assessing the overconsolidation ratio of an undisturbed soil sample.

One-Dimensional Strain Research of Coral Mud Based on a Modified Burgers Model Considering Stress History

“…At present, when analyzing a compression test of sediment under different loads, most methods analyze the time-strain relationship under each level of load. These analysis methods are fragmented and cannot take into account the influence of the historical loading, unloading, and reloading processes of the sediment [20]. Figure 3 shows that the timestrain relationship under each load level is related to all previous load levels; therefore, this study extends the modified Burgers model.…”

MATERIALS оf All-Russian scientific and practical Conference and Exhibition «FIELD AND LABORATORY METHODS OF SOIL INVESTIGATIONS ‒ PROBLEMS AND SOLUTIONS»

“…Поскольку переход от упругого к пластическому поведению не всегда однозначно идентифицируем, многими исследователями были предложены различные геометрические построения [6]. В качестве теоретического обоснования нередко используются уравнения идеального адиабатического процесса [18,36].…”

The compressibility of natural and reconstituted marine clays

“…In his paper, Butterfield (2011) tabulated the ðC 0 0 =C 0 c Þ ratios for 12 samples of seven different clays and silty clays; the average value of the ratios was 0·596, essentially identical to log(S), from which one might conclude that log 10 ðSÞ ¼ log 10 ð4Þ ¼ 0Á60 ≈ ðC 0 0 =C 0 c Þ provides the ratio of the value of m v for a reconstituted marine clay sample to that of a natural in situ one, as in Figure 7, and an explanation of S.…”

“…A log(v) against log(r (Butterfield, 1979(Butterfield, , 2011, is analogous to the swelling index C s associated with the e−logðs , as Burland (1990) and Skempton (1970) did.…”

“…Embedded in Burland's analysis is an empirically extrapolated curve passing through two points on the e against logðs It was established by Butterfield (1979Butterfield ( , 2011 and subsequently confirmed, also recently by Suddeepong et al (2015), that such a logðvÞ−logðs 0 v Þ interpretation of the data offers a much improved linearity (closely linear plots) for many soils (in particular clay and silty-clay soils) over a wide range of s 0 v values; a gradient that generates natural strains directly and is therefore applicable to large strain deformation; compression equations that are independent of the base of the logarithms used for plotting; and a satisfactory interpretation of the earlier-mentioned difference in soil stiffness.…”