Model
Digital Document
Publisher
Florida Atlantic University
Description
The characterization of silty soils is usually designated by the percentage of silt
contained within the soil matrix, along with the soil’s void ratio, which is used to
describe the soil’s current state. The use of these parameters to assess a soil’s strength
and undrained behavior is limited when finer material is contained within the soil.
Therefore, additional parameters must be considered in order to correctly assess the
strength and liquefaction potential of silty soils. These additional parameters include the
skeleton void ratio, equivalent void ratio and granulometric factors. The current research
investigates the influence of granulometric parameters, specifically the Median Grain
Size Ratio (D50/d50), denoted as μDR (or MDR within graphs and charts), on the strength
and liquefaction potential of loose silty sands. A series of undrained monotonic triaxial
compression tests (σ3’= 69, 83, and 103 kPa) are performed on reconstituted soil samples,
using three different base sand samples and a constant silt material. As a result, three distinct median grain size ratios (μDR = 4.2, 6.75, and 9) were tested with fines content
ranging from 0-30% for each μDR. The undrained shear strength at all confining pressures
tends to increase with in μDR; beyond 10% fines content there was no noticeable influence
of μDR. At any μDR the excess PWP is higher than that of clean sand, when fines content is
larger than 5% fines content. The slope of the instability line and phase transformation
line are directly affected by the μDR and fines content, with an increase in the instability
line and decrease in the phase transformation line with a growing μDR. The results
indicate loose granular fills can be designed to be stronger and more resilient under
extreme conditions by careful choice of materials in which the μDR>6.75 and the fines
content does not exceed 10%.
contained within the soil matrix, along with the soil’s void ratio, which is used to
describe the soil’s current state. The use of these parameters to assess a soil’s strength
and undrained behavior is limited when finer material is contained within the soil.
Therefore, additional parameters must be considered in order to correctly assess the
strength and liquefaction potential of silty soils. These additional parameters include the
skeleton void ratio, equivalent void ratio and granulometric factors. The current research
investigates the influence of granulometric parameters, specifically the Median Grain
Size Ratio (D50/d50), denoted as μDR (or MDR within graphs and charts), on the strength
and liquefaction potential of loose silty sands. A series of undrained monotonic triaxial
compression tests (σ3’= 69, 83, and 103 kPa) are performed on reconstituted soil samples,
using three different base sand samples and a constant silt material. As a result, three distinct median grain size ratios (μDR = 4.2, 6.75, and 9) were tested with fines content
ranging from 0-30% for each μDR. The undrained shear strength at all confining pressures
tends to increase with in μDR; beyond 10% fines content there was no noticeable influence
of μDR. At any μDR the excess PWP is higher than that of clean sand, when fines content is
larger than 5% fines content. The slope of the instability line and phase transformation
line are directly affected by the μDR and fines content, with an increase in the instability
line and decrease in the phase transformation line with a growing μDR. The results
indicate loose granular fills can be designed to be stronger and more resilient under
extreme conditions by careful choice of materials in which the μDR>6.75 and the fines
content does not exceed 10%.
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