RELIABILITY-BASED DESIGN PROCEDURE OF AXIALLY LOADED PILES

Geotechnical engineering involves many different and complex materials and many different mechanisms of behaviour. The direct use of experience as a guide to the prediction and design is effective provided these are understood. Geotechnical engineering is a relatively new science. Its successful application to prediction requires realistic assumptions to be made, and predictions must be tested against reality. Methods of prediction need then to be refined. An example of the importance of making realistic assumptions is examined in this paper. It includes the effects of soil properties on the ultimate capacity of axially loaded piles. Better analysis offers better prediction and better understanding. Both are only possible when reality is modelled. There are occasions when mechanisms are too complex for predictive analysis. Prediction must then be based directly on experience, applied with an understanding of the mechanisms involved. Moreover, methods of analysis may become too sophisticated for everyday use. However, pseudo-analysis, involving standardized methods based on oversimplified and unrealistic mechanisms of behaviour and material properties, is dangerous. The use of engineering experience as a guide to prediction and design may offer a more effective alternative, provided it is based on a realistic understanding of mechanisms and materials. In this paper, a procedure is recommended to estimate the bearing capacity of axially loaded piles based on reliability calculations. The procedure is an extension of the point estimate method in which the expected values of the standard deviation of the capacity and demand functions are calculated. The probability of failure, the reliability, central factor of safety and reliability index are calculated as appropriate. The procedure is then applied to two cases where the pile in the first case is driven in sand while in the second, it is driven in clay

Variation of Y-Chromosomal STRs in Yezidi and Chaldean Population in Iraqi Kurdistan

Purpose: Because many ethnic groups live in the northern part of Iraq which represents the Iraqi part of Kurdistan. Short tandem repeats are widely used in population genetics and forensic science. This research aims to analyze the Y-chromosomal STR markers of the two ethnic groups Yezidi and Chaldean. Subjects and Methods: A DNA from Peripheral blood from a total of 44 unrelated males was extracted (22 for each ethnic group) and analysis for eight STRs of the Y-chromosome (Y-GATA-H4, Y-GATA-C4, DYS458, DYS456, DYS448, DYS437, DYS392 and DYS19). Then, the PCR products were run on 10% gel of polyacrylamide and stained by silver nitrate. The results were analyzed by Power marker V3.25 and dendogram created by Mega X software. Results: The highest diversity observed at Y-GATA-C4 (GD: 0.81) while lowest diversity was observed at DYS456 (GD: 0.64) at Yezidi group. At Chaldean group DYS458 (GD: 0.88) was the most diverse, while the least diverse marker was in Y-GATA-H4 0.66 in Chaldea and in Chaldean samples loci DYS458. The marker Y-GATA-C4 was found to be the most informative marker in both groups with PIC value of 0.8605. Conclusions: The study confirmed the high discrimination ability of the Y-STRs analysis and providing dataset on these two ethnic groups of Iraqi Kurdistan. The dendogram of Yezidi and Chaldean datasets reveals that the Yezidi individuals are more closely related to each other as compared to Chaldean group because Yezidi people because of intermarriage among them more than the Chaldean

Y-chromosomal STR variation in Kurds and Arabs population in Iraqi Kurdistan

Background: The Iraqi Kurdistan local population involves more than eight gatherings of tenants. The Muslim Kurds make up most of the population and after that the Yezidi Kurds. Alternate gatherings incorporate Armenians, Assyrian, Chaldea, Syriacs, and little minority of Arab and Turkmen individuals.Methods: A total of 36 unrelated males from the two population groups in Iraqi Kurdistan: Kurds and Arabs were analyzed for eight Y-chromosome STRs (DYS19, DYS392, DYS437, DYS448, DYS456, DYS458, DYS635 and Y-GATA-H4). Total DNA from blood cells was extracted using DNA extraction Kit.Results: A number of genetic parameters such as mean number of alleles, allele frequency, gene diversity, polymorphic information content (PIC), and genetic distance were calculated using Power Marker V3.25 software. The DYS458 had the highest diversity (GD: 0.883), while loci DYS456 and Y-GATA-H4 had the lowest (GD: 0.574). The Dendrogram separated the populations into two main clades, the Kurd group and the Arab group except in one case only from the whole population.Conclusions: This study confirms the discriminating power of high-resolution Y-STR typing and provides first primary dataset on Iraqi Kurdistan samples. The comparison of Kurdish and Arab datasets reveals an interesting overall picture of isolation of Kurdish group. The primers DYS19, DYS448, DYS458, and DYS635 can be considered the best for their high PIC power

Enhancement consistency and compaction characteristics of clayey soil using nano silica material

The use of stabilizing technologies has significantly expanded in recent years specially when sites are frequently construction in poor land locations. This study suggests using nano-silica to improve clayey soil's functionality. A range of nano-silica concentrations (0, 0.1, 0.2, 0.4, and 0.8) were used. Laboratory testing was used to identify Atterber's limitations, the optimum moisture content (OMC), the maximum dry density (MDD), and microstructural examination. According to the study, treating soil with 0.4-0.6% nano-silica yields the best results. According to the result, the liquid limit (LL) and plastic limit (PL) are reached maximum at 0.6% nano-silica, while the plasticity index is at its lowest point. The results showed that incorporating nano-silica into clay samples will lower the maximum

Behavior of Partially Saturated Cohesive Soil under Strip Footing

In this paper, a shallow foundation (strip footing), 1 m in width is assumed to be constructed on fully saturated and partially saturated Iraqi soils, and analyzed by finite element method. A procedure is proposed to define the H – modulus function from the soil water characteristic curve which is measured by the filter paper method. Fitting methods are applied through the program (SoilVision). Then, the soil water characteristic curve is converted to relation correlating the void ratio and matric suction. The slope of the latter relation can be used to define the H – modulus function. The finite element programs SIGMA/W and SEEP/W are then used in the analysis. Eight nodded isoparametric quadrilateral elements are used for modeling both the soil skeleton and pore water pressure. A parametric study was carried out and different parameters were changed to study their effects on the behavior of partially saturated soil. These parameters include the degree of saturation of the soil (S) and depth of water table. The study reveals that when the soil becomes partially saturated by dropping water table at different depths with different degrees of saturation, the bearing capacity of shallow foundation increases about (4 – 7) times higher than the bearing capacity of the same soil under saturated conditions. This result is attributed to matric suction value (i.e negative pore water pressure). The behavior of soil in partially saturated condition is like that of fully saturated condition but with smaller values of displacement. It is found that the settlement is reduced when the water table drops to a depth of 2 m (i.e. twice the foundation width) by about (92 %)

BATTER PILES UNDER INCLINED COMPRESSIVE LOADS

The behaviour of batter piles under inclined compressive loads is of considerable importance,yet, not enough information is available in literature on the subject. The tests canied out in this paper were performed on a single inclined pile under various load inclinations in sand. The results indicate that the highest ultimate compressive load for vertical pile occurs at (30) load inclination. At small load inclinations, a positive batter pile has greater ultimate compressive load than that of a negative batter pile. The trend changes at higher Ioad inclinations. The slip surface analysis is recognised to be too complicated to have a definite solution

A COUPLED DYNAMIC FINITE ELEMENT ANALYSIS OF SATURATED SANDS

A general mixed finite element formulation (u - w - ) is presented in this paper. This formulation includes the inertia effects and the soil skeleton is considered compressible. The application of this formulation in solving soil dynamic problems of saturated sand is made by governing the boundary conditions concerning the pore fluid pressure. A problem of soil column subjected to an instantly applied surface loal is solved. The solid skeleton and pore fluid pressure are each modelled with ten 4- noded isoparametric elements. The results are compared with those obtained by Zienkiewic z et al. (1988)' It is concluded that the undamped response of displacement and pore pressure oscillates significantly with the increase of time step lenght

Effects of Gasoline and Smoking on Lipid Profile and Liver Functions among Gasoline Exposure Workers in Iraq

Introduction: The rapid and recent rise in the pandemic of cardiovascular disease implies that the environment plays a significant role. Numerous biological systems, such as the cardiovascular, blood-forming organs, liver, and kidneys, can be affected by gasoline and smoking. Because filling station employees, repair service workers, gasoline truck drivers, and refinery workers are all at a greater risk of being exposed to gasoline fumes. Even though gasoline and smoking have been investigated for so many years, few studies have looked into the effects of gasoline exposure combined with smoking on a variety of physiological mechanisms. As a result, we propose that combining gasoline exposure with smoking is a risk factor for cardiovascular diseases and impaired hepatic function. Methods: The study included 95 male adult volunteers who worked with gasoline and were exposed to different fuel derivatives as study group and age and sex-matched seemingly healthy non-exposed people as the controls. Questionnaire interviews were used to collect socio-demographic data and a standard technique was used to collect the blood samples. The levels of cholesterol, HDL4, LDL-C, triglyceride, and VLDL were measured, as well as for liver enzymes ALP, AST, ALT, indirect bilirubin, direct bilirubin, and total bilirubin were measured. Results: Our data suggest that smoking with gasoline exposure causes an increase in total and bad cholesterol levels, as well as a significant shift concerning the control group in lipid profile and liver enzymes. the exposed group had higher levels of ALP, and AST and significantly increased. In the nonsmoker exposed group D-bilirubin decreased in comparison to the control and exposed smoker group. Conclusion: This research concluded that the liver enzymes (ALP, AST, ALT) were higher among workers who smoke and are exposed to gasoline than in control subjects, similarly, the bad cholesterol also increase. Therefore, people who smoke and are handled with gasoline are at a higher risk of having heart and hepatic diseases

INVESTIGATION ON THE USE OF MICROPILES FOR SUBSTITUTION OF DEFECTED PILES BY THE FINITE ELEMENT METHOD

Micropiles are small diameter, cast in – place or grouted piles with steel pipes of (50 to 300 mm) diameters and driven by boring machine. Despite their small wall thickness, high bearing capacity of micropiles provides both axial and pullout resistance.nThis paper is directed to study the behavior of micropiles under static and dynamic loading conditions using the finite element method. The program OpenSees is used in the analysis, it is open – source program, provides information about the software architecture, access to the source code, and the development process. The program is based on the basic commands, which are written in Tcl (pronounced, "tickle"; tool command language). A model for groups of laterally loaded pipe piles in sand was adopted to study the effect of defects on their lateral performance. The geometric arrangement consisted of group series of 2, 4 and 6 equally spaced piles. Eight node brick elements are used to model the pile and the surrounding soil. It was concluded that the deflection of laterally loaded piles decreases when inserting steel micropiles beside the defect pile at two opposite directions. The increase in the group deflection is greater when the defected pile is modeled in the front row

THEORETICAL SIMULATION OF STRESS-STRAIN RELATIONS FOR SOME IRAQI CLAYS USING THE ENDOCHRONIC MODEL

A constitutive law can be defined as a mathematical functional relation between physical quantities such as stress and strain and may take other factors like time ,temperature and additional material properties into account. In this paper , the endochronic model is used to predict the stress-strain relations of two Iraqi clays. This model is a viscoplastic one but without introducing a yield surface. It encompasses material behaviour such that the current stress state is a function of strain history through a time scale called “intrinsic time” which is not the absolute time but a material property. The simulation showed that the model overestimates the strains for all cases studied. This may be attributed to the material parameters which require a parametric study to determine their actual values for Iraqi clays.