Small-strain stiffness of compacted silty sand using a proximitor-based suction-controlled resonant column device

Most previous studies have focused on the small strain stiffness of sedimentary soil while little attention has been given to residual soils with different properties. Most studies also neglected the effects of the deviator stress, which is extensively involved in civil engineering. This note considers the effects of the deviator stress on the small-strain stiffness of natural granite residual soil (GRS) as established from resonant column tests performed under various stress ratios. Although increasing the stress ratio results in a greater maximum shear modulus for both natural and remolded residual soils, remolded soil is more sensitive to changes in the stress ratio, which highlights the effects of soil cementation. The data herein offers new insights to understand the stiffness of residual soil and other weathered geomaterials.

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Experimental Investigation on Small-Strain Stiffness of Marine Silty Sand

Journal of Marine Science and Engineering ◽

10.3390/jmse8050360 ◽

2020 ◽

Vol 8 (5) ◽

pp. 360 ◽

Cited By ~ 1

Author(s):

Qi Wu ◽

Qingrui Lu ◽

Qizhou Guo ◽

Kai Zhao ◽

Pen Chen ◽

...

Keyword(s):

Experimental Investigation ◽

Void Ratio ◽

Reduction Rate ◽

Confining Pressure ◽

Small Strain ◽

Silty Sand ◽

Bender Element ◽

Small Strain Stiffness ◽

Alternative State ◽

State Index

The significance of small-strain stiffness (Gmax) of saturated composite soils are still of great concern in practice, due to the complex influence of fines on soil fabric. This paper presents an experimental investigation conducted through comprehensive bender element tests on Gmax of marine silty sand. Special attention is paid to the influence of initial effective confining pressure ( σ c 0 ′ ), global void ratio (e) and fines content (FC) on Gmax of a marine silty sand. The results indicate that under otherwise similar conditions, Gmax decreases with decreasing e or FC, but decreases with increasing FC. In addition, the reduction rate of Gmax with e increasing is not sensitive to σ c 0 ′ , but obviously sensitive to changes in FC. The equivalent skeleton void ratio (e*) is introduced as an alternative state index for silty sand with various FC, based on the concept of binary packing material. Remarkably, the Hardin model is modified with the new state index e*, allowing unified characterization of Gmax values for silty sand with various FC, e, and σ c 0 ′ . Independent test data for different silty sand published in the literature calibrate the applicability of this proposed model.

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Effects of net stress and suction history on the small strain stiffness of a compacted clayey silt

Canadian Geotechnical Journal ◽

10.1139/t06-129 ◽

2007 ◽

Vol 44 (4) ◽

pp. 447-462 ◽

Cited By ~ 57

Author(s):

Roberto Vassallo ◽

Claudio Mancuso ◽

Filippo Vinale

Keyword(s):

Shear Stiffness ◽

Small Strain ◽

Resonant Column ◽

Stress History ◽

Small Strain Stiffness ◽

Maximum Value ◽

Clayey Silt ◽

Triaxial Cell ◽

The Mean ◽

Suction History

An experimental study was carried out to investigate the effects of the mean net stress and suction history on the initial shear stiffness, G0, of a compacted clayey silt. Isotropic tests were performed using two suction-controlled devices, a triaxial cell and a resonant column torsional shear (RCTS) cell, so as to investigate the volumetric behaviour of this material. As for saturated soils, one can expect to find a strong correlation among stress history, volumetric state, and G0. Initial shear stiffness was measured almost continuously along various isotropic stress paths, including compressions and drying–wetting single stages or cycles, by using the RCTS cell. The collected data demonstrate a strong dependency of G0 on mean net stress (p – ua) and suction (ua – uw). Cycles of suction, in particular increasing suction beyond the past maximum value, induce significant accumulation of irreversible strains and increase of stiffness, confirming that G0 is not univocally related to the stress state (p – ua, ua – uw).Key words: unsaturated, compacted, small strain, stiffness, volumetric behaviour, stress history.

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Small strain behavior of a silty sand in controlled-suction resonant column torsional shear tests

Canadian Geotechnical Journal ◽

10.1139/t01-076 ◽

2002 ◽

Vol 39 (1) ◽

pp. 22-31 ◽

Cited By ~ 105

Author(s):

Claudio Mancuso ◽

Roberto Vassallo ◽

Anna d'Onofrio

Keyword(s):

Shear Stiffness ◽

Small Strain ◽

Bulk Water ◽

Silty Sand ◽

Resonant Column ◽

Soil Behavior ◽

Soil Response ◽

Strain Behavior ◽

Torsional Shear ◽

Constant Suction

An experimental study has been carried out using a new resonant column torsional shear cell to investigate the small strain behavior of an unsaturated compacted silty sand. The device, recently developed at the Dipartimento di Ingegneria Geotecnica di Napoli (Italy), is fitted for controlled-suction testing using the axis-translation technique. Both optimum and wet of optimum compacted specimens have been tested to analyze the effects of suction and fabric on soil behavior. Shear stiffness measurements have been taken during constant-suction tests. Collected data indicate an S-shaped initial shear stiffness versus suction variation, which can be explained considering the progressive change from a bulk-water regulated soil response to a menisci-water regulated soil response. A model is proposed to account for the observed trend. Results highlight significant effects of suction and fabric on soil behavior.Key words: compacted soil, small strain behavior, shear stiffness, suction, soil fabric.

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