Print ISSN: 1681-6900

Online ISSN: 2412-0758

Volume 35, Issue 2

Volume 35, Issue 2, April 2017, Page 97-181

Experimental and Numerical Analysis of Piled Raft Foundation Embedded within Partially Saturated Soil

M.R. Mahmood; S.F.A. Al-Wakel; A.A. Hani

Engineering and Technology Journal, 2017, Volume 35, Issue 2, Pages 97-105

This paper presents an experimental and numerical study to investigate the load carrying capacity of piled raft foundation embedded within partially saturated sandy soil. The effect of matric suction on the bearing capacity of the foundation system was investigated. The experimental work consists of two models of foundation, circular raft foundation and circular piled raft foundation. The circular raft foundation has dimensions of 10cm in diameter, and 2.5cm thickness, while the piled raft foundation has the same dimensions of the circular raft model but with a single pile of 2.0cm in diameter and 40.0cm in length fixed at the center of the raft. Both models are loaded and tested under both fully saturated condition and unsaturated conditions, which are achieved by, predetermined lowering of water table. The lowering of water table below the soil surface was achieved in to two different depths to get different values of matric suction and the relationship between matric suction and depth of ground water table was measured in suction profile set by using three Tensiometers (IRROMETER). The soil water characteristic curve (SWCC) estimated by applying fitting methods through the software (SoilVision). A validation process then was carried out for the case of circular piled raft foundation with lowering the water table 45cm bellow soil surface in the aid of a sufficient finite element computer program ABAQUS 6.12. An eight-node axisymmetric quadrilateral element CAX8RP and CAX8R were used to simulate the soil continuum and piled raft respectively. The interaction method used to simulate the intersect surfaces of the system (pile-raft-soil) is a surface-to-surface discretization method under the concept of master and slave theory. The behavior of piled raft material is simulated by using a linear elastic model while the behavior of soil is simulated by an elasto-plastic model by the use of the Mohr-Coulomb failure criterion. The results of the experimental work demonstrate that the matric suction has a significant role on the bearing capacity of all tested models. It shows that the ultimate bearing capacity of circular raft foundation under a partially saturated condition is increases by about (7.0-8.0) times than the ultimate bearing capacity of fully saturated condition when lowering the water table 45 cm below the soil surface. While the ultimate bearing of circular piled raft foundation under partially saturated condition increases by about (8.0-9.0) times than the ultimate bearing capacity of fully saturated condition when lowering the water table 45 cm below the soil surface. The results of the ultimate bearing capacity of piled raft foundation that obtained from the experimental model and from the numerical modelling for the same soil condition and same matric suction indicate that a successful validation is achieved for the simulation process.

Effect of Surfactant Additives on Phase Inversion in Oil-Water Pipe Flow System

A.A. Alwasiti; N.M. Farhan

Engineering and Technology Journal, 2017, Volume 35, Issue 2, Pages 106-110

This research investigates the effect of surfactant additives on phase inversion point in the oil-water flow in horizontal pipe. Two types of surfactants were used in the experiments; anionic type (sodium lignosulfonate (SLS)) at 200 ppm and cationic type (hexadecyltrimethyl ammonium bromide (CTAB)) at 100 ppm. The experiments were carried at mixture velocities (0.8, 1, 1.9 and 2.3) m/s. The results showed that the phase inversion points are unaffected by surfactant addition or velocity at low mixture velocities while they shifted downward at high mixture velocities. The experiments show also that anionic surfactant addition caused a forward shifting in phase inversion point and downward shifting in the addition of cationic surfactant at high mixture velocities.

Controlling of Time-Overrun in Construction Projects in Iraq

T.A. Khaleel; I.Z. Hadi

Engineering and Technology Journal, 2017, Volume 35, Issue 2, Pages 111-117

This paper is about analyzing time overrun in construction projects. The principle targets are centered on researching the causes, effects and strategies for controlling time over-run in development ventures in Iraq. The study has been accomplished based on previous researches in addition to a questionnaire form and case studies. Forty-two factors of time overrun causes under four main responsible parties were distinguished (owner, consultant, contractor, others). Eight major impacts of time overrun were also identified. The questionnaire form was formulated based on the above data and was distributed to the selected respondents which are professionals in construction industry. Depending on the results of the questionnaire form, the major origin of time overrun was found that the contractor is the responsible for most of the time overrun (i.e. Contractor's financial difficulties Shortage of skilled manpower and the other causes related to him). The most important two impacts of time overrun were Increase the cost of the project, Quality degradation and Increasing in overhead expenses, the highest percentage of time-overrun in the nine existed project 319% and the most common causes were (change in economic condition and Company's lack of experience).According to the research findings a management system has been proposed to control on the time overrun in construction projects.

Effect of SiC Particulate on Glass Fibers Reinforced Polymer Composites in Erosive Wear Environment

R.H. Abdel-Rahim; Z.F. Atya

Engineering and Technology Journal, 2017, Volume 35, Issue 2, Pages 118-123

In this study the physical property, mechanical properties and erosion wear of pure epoxy and hybrid composites were studied. Composites were prepared and investigated by Hand lay-up molding. Pure epoxy and hybrid compositions were prepared, 4% and 8% volume fractions of glass fibers as reinforcement and 4% and 8% of SiC as filler particles. The investigated physical property is density while the mechanical property was hardness. Solid particles erosion wear tests are also carried out. The experimental results showed that increased volume fraction of glass fibers to (8%) led to increase the (density). The maximum density is equal (1.661gm/cm3). Hybrid composite with (Epoxy +8%GF+8%SiC) has the maximum hardness of (82) shore D. The particle-contained water jet type experimental erosion test results that the reinforcement volume fraction as well as particles distribution and bonding has considerable effect on the wear of epoxy composites. It was found that the better resistance was for hybrid composites (Epoxy+8%GF+4%SiC) at angle 30°, erodent size 800 μm, and time 10 hour.

Study the Effect of Nano Ceramic Particles on Some Physical Properties of Acrylic Resins

Q.A. Hamad

Engineering and Technology Journal, 2017, Volume 35, Issue 2, Pages 124-129

In the present research, study the effect of adding two different types of reinforcing particles, which included: nano-alumina (nano-Al2O3) and nano-silica (nano-SiO2), that added with different volume fractions of (1%, 2% and 3%), on some physical properties of composite prosthesis complete denture base materials by using self (cold) cure poly methyl methacrylate (PMMA) resin as new fluid resin matrix. In this research, the composite prosthetic dentures specimens consist of two groups were prepared by using (Hand Lay-Up) method according to the types of reinforced particles, which includes: the first group consists of PMMA resin reinforced by nano-alumina particles, and the second group consists of PMMA resin reinforced by nano-silica particles. The physical tests were performed on these specimens include (water absorption test and thermal behaviors test). The result of this study showed the values of (thermal conductivity and thermal diffusivity) properties increased with increasing the volume fraction of both (nano-Al2O3 and nano-SiO2) particles in PMMA complete denture base materials. While, the values of (water absorption and specific heat) properties decreased. In addition, the addition of (nano-Al2O3) particles has a noticeable effect on the all properties of composite material for prosthetic denture base specimens more than the (nano-SiO2) particles.

Heat Transfer Performance Improvement in the Split Units in Humid Environment through Drain Water Circulation

M.A.H. Alzuhairi

Engineering and Technology Journal, 2017, Volume 35, Issue 2, Pages 130-133

The only way to ease extremely hot days during the summer is to resort to cooling systems to feel comfort. This idea brings an end to failure in cooling process to hot summer days, energy saving, and lets you rest. By recycling the water drained from the indoor unit through simple distributor fixed on the outdoor unit. There is two advantages due to rapid vaporization of the compensating draining by fan during hot air of weather: avoid the corrosion due to using the drain water in the cooling process, and get rid and consumption of the draining water to avoid any problem where place drained. The drain water is almost high purity (TDS < 50 ppm), and dust-free by filters of indoor unit lead to no salts accumulation, and reduce probability of fins corrosion of outdoor heat exchanger in salt medium. Experimental results indicate that the increasing of the heat transfer is obtained by using low temperature water, which ranging (5-15 oC) and the decreasing depend upon the hot air (30-55 oC), over the temperature during the summer in Iraq as well as the difference values in heat capacities between air and water. Applying this idea will result in power consumption reduction by the range (1 – more than 4 Amperes).

Treatment of Wastewater from Oil Refinery by Adsorption on Fluidized Bed of Stem Date

M.G. Albarazanjy

Engineering and Technology Journal, 2017, Volume 35, Issue 2, Pages 134-138

A fluidized–bed adsorbed system was used to study the removal efficiency of oil and the total dissolved solids (TDS) from on oily wastewater. Adsorption was developed using stem date. The range of oil concentration used was (100-500ppm), and the range of [TDS] was (600  1500 ppm). The effects of flow rate at (18  28 L/min), particle size of stem date (3-5 mm) and bed height (25-40 cm) on the adsorption efficiency of removal were studied. The results showed that the removal efficiency reaches high percent about (71%) with decreasing particle size, volumetric flow rate and increasing bed height and initial oil concentration contained in treated wastewater.

Recovery of Cobalt and Lithium from Spent Lithium Ion Batteries

N.E. Abdul Latif; A.M. Ahmed

Engineering and Technology Journal, 2017, Volume 35, Issue 2, Pages 139-148

In this research a combination of mechanical separation, reductive leaching and chemical precipitation are used to regain Li as Li2CO3 and Co as Co(OH)2 from waste lithium ion batteries. First batteries are dismantled and different component are separated. Anode and cathode foils are grinded and sieved to extract Al and Cu from spent battery powder. The separation efficiency for copper and aluminum are 97.68% and 84.41% respectively. The separated powder is leached with sulfuric acid and hydrogen peroxide solution to dissolve cobalt and lithium. The effects of sulfuric acid concentration, time, temperature, concentration of hydrogen peroxide and S/L on the leaching efficiency for cobalt and lithium are studied. Design of experiments by Taguchi method is used to determine experiments conditions, analysis the results, and identify the optimum leaching conditions. The optimum leaching conditions are 1.5 M acid concentration, 60 minute, 60 °C, 15% H2O2, and 40 g/l solid to liquid ratio. Leaching efficiencies of 94.07% Co and 98.15% Li are achieved with these optimum conditions. Leaching solution of the optimum experiment is used to recover cobalt as cobalt hydroxide and lithium as lithium carbonate by chemical precipitation. An equivalent volume of 4M NaOH is used to precipitate cobalt as cobalt hydroxide. After 1 hour 99.98%, Co is precipitated and collected by filtration and dried. After collection of the Co(OH)2 product, the remaining solution is treated with equivalent volume of "saturated solution" of Na2CO3 at 100 °C to recover lithium as Li2CO3. After 1 hour, 80 – 85 % Li is precipitated, filtrated and dried. Precipitation products are investigated with XRD, which confirmed that cobalt hydroxide and lithium carbonate are recovered from leaching solution.

Brazing of Pure Aluminum by Aluminum Silicon Filler Metal Alloys

B.S. Mahdi; N.F. Mohammed

Engineering and Technology Journal, 2017, Volume 35, Issue 2, Pages 149-154

The aim of this work is to study the effect of clearance, on the metallurgical aspects of diffusion rate and mechanical properties of the brazing joint using two types of Silicon-Aluminum filler metal alloys on the commercially pure aluminum base metal. The brazing process experiments done by joining Al-alloys (1100) type by a brazing process using (4043, 4047) filler metals at 600-650oC. Two types of joint accomplished, inclined and curvature design. To indicate the brazing joint performance the specimens tested for single shear tensile test and metallurgical testing using optical and scanning electron microscope assisted with energy dispersive detector. Diffusion rate results according to joint clearance and brazing time accomplished using optical microscope images for joints cross sections and data gained with assisting of ImageJ® software. The joint sections analyzed using EDS detector and X-Ray analysis to observe the produced phases. The major phases of brazed joints using 4047 filler alloy gives (Al, Fe3Si, Al 0.3Fe3Si0.7) and (Al 0.3Fe3Si0.7) for the 4043 filler alloy. The two filler alloys (5 and 12%Si) had equivalent tensile strength of 176 and 145MPa respectively, therefore the maximum joint efficiencies are 172% for AL5%Si filler alloy and 142% for AL12%Si filler alloy which mean that the tensile strength of the brazed joint had values greater than 100%.

Improved Sliding Mode Controller for a Nonlinear System Based on a Particle Swarm Optimization Technique

A.K. Hamoudi; N.O. AbdulRahman

Engineering and Technology Journal, 2017, Volume 35, Issue 2, Pages 155-162

In this paper, the performance of the classical Sliding Mode Controller (CSMC) is improved by using the Particle Swarm Optimization (PSO) technique. The PSO technique is used to obtain the optimal values of the CSMC parameters such as the gain K and the slope of sliding surface λ, and as a result, the response of the system is improved by decreasing the settling time of the system and makes the steady state error equal to zero. A single inverted pendulum, which is considered an example of a nonlinear system, has been used for testing the proposed controller. The simulation results are implementing by using the Programming and Simulink of Matlab, and the result shows a good validity of the proposed controller.

Study the Effect of adding Natural Rubber and Polymethyl Methacrylate to the Epoxy Resin on the Quantitative Analysis and its Mechanical Properties

S.E. Salih; W.M. Salih; M.A. Abdul hameed

Engineering and Technology Journal, 2017, Volume 35, Issue 2, Pages 163-171

From polymer blends can be obtained more useful properties compared with single polymer. In this work, polymer blend (Epoxy (EP): Natural Rubber (NR)) with different ratios of NR (0, 2, 3.5 and 5%wt) and ternary polymer blend with ratio of (Epoxy: 2%NR: 5% wt. PMMA) were prepared. The Mechanical properties were included (tensile, flexural, impact, compression) tests and analytical physical properties (FTIR, SEM) were investigated, and the results show that the elongation values, impact strength and fracture toughness for polymer blend system (Epoxy: NR) were increment with increase natural rubber ratio in the polymer blend system. Whereas fracture strength, young’s modulus, flexural strength, flexural modulus and maximum shear stress decreased. The highest values of impact strength and fracture toughness were (0.041KJ/m2) and (0.321 MPa √m) respectively for polymers blend (95% Epoxy: 5% NR). Ductile fracture in rubber modified epoxy may be produce from the elastomeric nature of rubber which is represents an energy dissipating center.

Seepage Analysis through an Earth Dam (KHASA-CHAI Dam) as a Case Study

A. A. Abdulsattar; M.R. Faris; A.J. Zedan

Engineering and Technology Journal, 2017, Volume 35, Issue 2, Pages 172-181

In this research KHASA-CHAI Dam that consists of zoned embankment was investigated by using finite element method. The finite element computer software SEEP/W was used. Experimental works were done to the soils that enters in the construction of the dam to obtain the different parameters that SEEP/W software need in order to complete the analysis. The dam at its actual design was investigated by considering the water in the reservoir to be at maximum, minimum and half filled with water. Then the control of seepage and exit gradient through the dam were investigated by studying the effect of changes in the construction of the dam. It was concluded that the core in the dam has an important effect on decreasing the seepage quantity through the dam body. The presence of filters in the dam has small effect on increasing seepage quantity, but they have great effect on decreasing exit gradient.