Influence Of Hydraulic Properties Research Articles

Working mechanism of a new wicking geotextile in roadway applications: A numerical study

Woven geotextiles are often to be used in roadways for reinforcement purposes due to their higher tensile strengths. In the design of a woven geotextile for practical applications, the focus is mainly put on its reinforcing effect, while its hydraulic behaviors are not major design parameters and the influence of hydraulic properties on the reinforcing effect is often ignored. However, woven geotextiles are predominantly made of polypropylene and polyester, which are hydrophobic. This characteristic can result in a capillary break effect which it is equivalent to raise the ground water table to the location where the geotextile is installed. Numerous researchers have reported that the moisture storage from a capillary break effect can be detrimental to the long-term performance of a pavement structure. Until now, no method is available to effectively resolve this issue.Recently a new type of wicking geotextile is produced which has the capability to laterally drain excess water in a roadway under both saturated and unsaturated conditions. Several field applications demonstrated its potential in improving pavement performance. This paper attempted to investigate the working mechanism of the wicking geotextile through numerical studies and quantify the benefits of the wicking geotextile in term of drainage performance in a pavement structure. A numerical model was developed and validated using column test results from existing literature. After that the drainage performance of the wicking geotextile under different working conditions was simulated and evaluated.

Influence of hydraulic properties on physically modelling slope stability and the definition of rainfall thresholds for shallow landslides

Physically-based models are recognized as a good tool for slope stability analysis and have been implemented for the definition of rainfall thresholds for landslides. In this study, a methodology for estimating rainfall intensity and duration thresholds for shallow sliding failure, using the physical model TRIGRS, was implemented in a tropical mountainous basin of the Valle de Aburrá (Colombia). The variation of pressure head and factor of safety during different rainfall events and hydraulic conditions is studied for specific grid cells. Steady state and a maximum pressure head were reached for each grid cell regardless of the different rainfall intensities and hydraulic conductivities simulated, but the time in which this condition is reached depends on these variables and occurs faster for steeper slopes. The influence of hydraulic properties on the stability results and the position of the rainfall intensity and duration thresholds were studied with parametric analysis. Very low values of saturated hydraulic conductivity do not allow rainfall intensity and duration thresholds to be developed. The rainfall threshold position also has a greater variation with respect to the parameters of the soil water retention curve and the initial infiltration rate (or long-term background rainfall rate) for low values of saturated hydraulic conductivity.

Effect of Drainage and Consolidation on the Pore Water Pressures and Total Stresses within Backfilled Stopes and on Barricades

The pore water pressures (PWPs) and total stresses during the placement of a slurried backfill in underground mine stopes are the key parameters for the design of barricades, built to retain the backfill in the stopes. They can be affected by the drainage and consolidation of the backfill. Over the years, several studies have been reported on the pressure and stresses in backfilled stopes by accounting for the drainage and consolidation. Most of them focused on the pressure and stresses in the stopes, few specifically on the barricades. The effect of the number of draining holes commonly installed through the barricade has never been studied. In this paper, the influence of hydraulic properties and filling rate of the backfill, stope size, barricade location, and number of draining holes is systematically investigated with numerical simulations. The results show that the stresses in the backfilled stope and on the barricade largely depend on the filling rate, hydraulic conductivity, and Young’s modulus of the backfill. The draining holes can significantly decrease the PWP, but only slightly the total stresses on the barricades in short term.

Mass transfer in electro-membrane separation of water systems

The article presents the results of mass transfer characteristics of electro-membrane systems. It is also shown the influence of hydraulic properties, experimental cell constructive parameters and initial concentration on mass transfer coefficient.