Osama K. Nusier

A reliability based approach for evaluating the slope stability of embankment dams

Abstract Embankment dams are important and costly civil engineering structures that provide an essential infrastructure for the management of water. One of the critical aspects of dam design is the analysis of stability and safety of the earth structure under various operating and environmental conditions. Traditionally, a deterministic approach is used for such analysis. However, the determination of variables such as soil strength parameters, pore pressure and other pertinent properties involves uncertainties, which cannot be handled in the traditional deterministic methods. It is, therefore, highly desirable to develop a reliability based analytical/numerical methodology for stability analysis of dams taking into account these uncertainties. Reliability and probability theories are developed in this paper for assessing the reliability index and the corresponding probability of failure of multi-layered embankment dams and slopes. Two definitions were used to calculate the reliability index (i.e. the normal distribution and the log–normal distribution). The computer program reslop was developed and validated by the Congress Street open cut failure case. The developed approach was used to study the stability of the King Talal embankment dam. The results are discussed and conclusions drawn.

Convective heat transfer of ferrofluid in a lid-driven cavity with a heat-conducting solid backward step under the effect of a variable magnetic field

ABSTRACT The effect of variable magnetic field on the mixed convective flow of a ferrofluid within a lid-driven cavity has been analyzed numerically. A heat-conducting solid block is located in the bottom part of the cavity. Governing partial differential equations have been formulated taking into account that the magnetic source is a point source located over the moving lid. Analysis has been performed for a wide range of Hartmann number, nanoparticles volume fraction, and magnetic number. It has been found that the growth of the magnetic number leads to the heat transfer enhancement.

Micropile technique to control upward movement of lightweight structures over expansive soils

A simplified analytical formulation is presented for the mechanism by which micropiles surrounded by compacted sand control the upward movement of lightweight buildings over expansive soils. This formulation identifies the significant variables influencing the performance of micropile reinforcement. A design methodology for micropile reinforcement utilizing the resulting formulation is proposed and illustrated by a hypothetical example.

Soil Air Permeability and Carbon Dioxide Flux Measurements from the Soil Surface

Abstract Air permeability has been recognized as an index of soil structure and used in attempts to characterize soil pore geometry. The importance of increased carbon dioxide in soil to agriculture comes from the direct effects of carbon dioxide (CO2) on root respiration of agricultural crops. In this study, the soil air permeability and CO2 flux values were obtained using two different apparatuses built and designed to measure air permeability and CO2 flux. Air permeability was obtained in clay soil using two different aggregate sizes. The average values obtained were 9.55×10−8 and 1.78×10−7 cm2 for the <2-mm and 2- to 5-mm fractions, respectively. Carbon dioxide flux from the soil surface of no‐till and bare plots under winter conditions was measured using another apparatus. The average CO2 flux for the no‐till plot was 2.88 g/m2‐day and for the bare plot was 1.31 g/m2‐day. These values were within the range of values obtained from other studies.

Influence of peatmoss on hydraulic properties and strength of compacted soils

Due to its high organic matter content, peatmoss can be highly beneficial to agricultural soil. In this research, the impact of varying organic matter contents at different compaction efforts on water retention, saturated hydraulic conductivity, and modulus of rupture of three soils (sandy loam, clay loam, and clay) has been investigated under laboratory conditions. Compaction changed the ability of the soils to hold water, increased modulus of rupture, and decreased the plant-available water-holding capacity of the soils. On the other hand, organic matter generally increased the ability of the soils to hold water, expanded the available water capacity, and decreased the modulus of rupture of compacted soils. Key words: Peatmoss, water retention, saturated hydraulic conductivity, modulus of rupture

Dependency of unit shaft resistance on in-situ stress: Observations derived from collected field data

In this study, a database comprised of 30 pullout pile load tests was collected from geotechnical literature and analyzed to investigate the dependency of unit shaft resistance on effective vertical stress. The collected database consists of steel pipe, timber, and concrete piles, with varying normalized penetration depth with respect to pile diameter, driven into loose to very dense sand. Different correlations for the uplift lateral earth pressure coefficient K, Bjerrum-Burland ratio β, and the average unit shaft resistance fave were derived using different assumptions. A comparison between measured and predicted capacities of the collected piles using the developed correlations indicated that the assumption of values of K and β that were constant with depth did not provide a reasonable fit for the measured capacities of the collected piles and thus this assumption is inappropriate. The best correlations for K and β that yield a reasonable fit to the measured capacities of the collected piles were found to be functions of sand relative density, pile diameter, and level of effective vertical stress. This indicates that average unit shaft resistance does not reach a limiting value, but rather continues to increase with depth. Moreover, the correlations for K and β in terms of effective stress revealed that average unit shaft resistance increases as pile diameter decreases and this increase depends on initial sand relative density. Comparisons of measured and predicted pullout capacities of the collected piles using the best-obtained correlations for K and β were made and compared to predictionsobtained from other methods. On the basis of these comparisons, it is concluded that the correlations for K and β in terms of effective stress give results comparable to those obtained from other methods, without stipulating limiting values for the average unit shaft resistance.

Water Resources Management Using Modeling Tools in Desert Regions: The Azraq Basin, Jordan

This research is aim to investigate holistic management of floodwaters in Jordan to better understand how this natural hazard can instead be viewed as a valuable natural resource. The groundwater resources in the study area are depleted by the domestic usage and irrigation uses. The limited amount of the groundwater in the area is attributed to the limited natural recharge through the wadi bed during the occurrence of floods. HEC-HMS model were used in order to estimate the surface runoff. A groundwater model for the study area was used to evaluate the effect of flood water on groundwater recharge using the existing volcanic cave. The result shows that Beer Al-Hamam cave with a volume of 20,000 m 3 , when used to store flood water and recharge it for groundwater. The groundwater table will rise (localy) in the range of 0.2 to .5 m per year.

Effect of Tillage Systems and Axle Load on Undisturbed Soil Hydraulic Properties

The effects of tillage treatment and axle load resulting from wheeled traffic on tilled soil (0 to 20 cm) were evaluated by measuring the changes in soil physical properties (bulk density and infiltration rate) and by measuring the impact on water retention in comparison with controlled plots. Data obtained from the experimental plots showed that infiltration rate was strongly affected by tillage treatments in 0‐ to 20‐cm depths. Dry bulk density was affected in 0‐ to 20‐cm depths by tillage treatments and axle load. Tillage system changed the ability of the soils to hold moisture and decreased the plant‐available water capacity.