Figure 1
Conceptual diagram showing the effect of (a) median particle size of uniform sand and (b) width of particle size distribution, on the shape of the soil-water characteristic curve (SWCC) of sand (Craig H. Benson et al. [14]).
Figure 2
Conceptual diagram presenting the effect of (a) the median particle size of uniform sand, and (b) the breadth of particle size distribution, on the parameters α and n (Craig H. Benson et al. [12]).
Figure 3
Typical soil water retention curve (Toll [59]).
Figure 4
Explanatory diagram of the drying and wetting processes in the porous network that is composed of cylinders with radius r; rm is the meniscus radius at the air-water interface (Do. [19]).
Figure 5
Schematic representation of the tensiometric method for the measurement of suction (Feia et al. [25]).
Figure 6
Experimental results used in this study (Feia et al. [25]).
Table 1
Characteristics of the used sands.
| Sand | dg50(μm) | Cu | emin | emax | ρs(t/m3) |
|---|---|---|---|---|---|
| NE34 | 206 | 1.5 | 0.557 | 0.884 | 2.65 |
| Type of sand | NEI-1 | NEI-2 | NEI-3 | ||
| Density index ID | 0.9 | 0.7 | 0.5 | ||
Figure 7
Variation of the degree of residual saturation as a function of the density index.
Figure 8
Calibration of the model on the basis of the experimental data for a) Sand NEI-1, b) Sand NEI-2, and c) Sand NEI-3
Table 2
Values of the parameters of the proposed model for the three types of sand.
| Sand | NEI-1 ID= 0.9 | NEI-2 ID= 0.7 | NEI-3 ID= 0.5 |
|---|---|---|---|
| Model parameters | |||
| α | 4.5 | 3.4 | 3 |
| n | 8.5 | 7.3 | 6 |
Figure 9
Evolution of the parameter α as a function of the density index ID.
Figure 10
Evolution of the parameter (n) as a function of the density index ID.
Figure 11
Validation of the model through the simulation of a test, with a density index ID=0.9 and uniformity coefficient Cu=1.6.
Table 3
Characteristics of the materials to be analyzed.
| Sand | D50 (mm) | Cu | emin | emax | ρs(g/cm3) |
|---|---|---|---|---|---|
| Type 1 | 0.18 | 1.5 | 0.51 | 0.79 | 2.65 |
| Type 2 | 0.37 | 2.85 | 0.47 | 0.75 | 2.65 |
| Type 3 | 0.42 | 2.47 | 0.47 | 0.76 | 2.65 |
| Type 4 | 0.5 | 5 | 0.44 | 0.77 | 2.65 |
Photo 1
Four types of sand.
Figure 12
Grain-size distributions of all four sands obtained by sieve analysis.
Figure 13
Water retention curves for all four types of sand.
Figure 14
Water retention curves for type 3 sand for different density index values.
Figure 15
Pore-access size distributions for all four types of sand.
Figure 16
Effect of sand density index on pore-access size distribution.
Figure 17
Comparison between the pore-access sizes of four types of sand.
Figure 18
Comparison between the results obtained by the proposed model and those calculated by the law of Della and Feia [47].