Nadher Hassan Jawad Al-Baghdadi

The research presents a numerical study of the interaction between single cavity and adjacent pile in homogeneous sandy soil by utilizing an efficient finite element formulation. A square cross sectional concrete pile, with (9) m length and (0.6) m width, has been used. The interface layer between pile and surrounding soil was represented by thin layer element. The research results indicate that, in the direction perpendicular to the direction of applied load, where the ratio between the distance from the cavity to the pile and cavity length (measured in the same direction), is equal or more than (1.7) the effect of cavity can be neglected. While the values of the maximum bending moment decrease with increasing of the above mentioned ratio, and it became constant when the ratio ≥ (2.0). The deformations around cavity increases with increasing lateral load and decreasing the above mentioned ratio, particularly in the nearest side of pile and these deformations are constant when the ratio ≥ (2.0).

The present paper submits a set geotechnical maps for the area of An-Najaf city, by using contour lines to represent the different geotechnical properties of the soil. The present research work is very important step toward preparing a geotechnical database for this region, to complete the geotechnical database over all the country, (Iraq). Using such a database is very important in geotechincal investigation, reconnaissance phase, of construction projects. Within this phase of site investigation, numbers, depths and locations of the boreholes needed, will be determined. A well known commercial software (SURFER 11), was used to produce the all the contour maps of geotechnical properties presented herein. A forty nine (49) contour maps were produced to cover the variations, within the geotechnical properties of the soil, to produce realistic description to these soil properties. Both Google maps and Universal Transverse Mercator coordinate system (UTM) have been used in the contour maps for easy use.

The basic concept of Soil nailing is to reinforce and strengthen the existing round by installing closely spaced steel bars, called “Nails”, into a slope as construction proceeds from “top-down”. This process creates a reinforced section that is in itself stable and able to retain the ground behind it. Soil Nailing technique is used to support new very steep cuts with advantage of strengthening the slope with excessive earth works to provide construction access and working associated with commonly used retaining systems. In the present research work a parametric study has been made using commercial computer program “Slide6“, which utilize different methods for solving slope stability problem, Bishop method has been used herein to analyze un nailed and nailed slopes with granular soil, different slope heights and angles have been considered. Some of nails parameters have been studied herein, positions of nail, length of nail, angle of nail inclination, and nail spacing. The optimum length of nail depends on height and angle of slope. The optimum angle of nail is found to be ranged between (10-25) degree down from the horizon, but it’s also relates with the angle of slope. The spacing of nail was found to be (1 m) to give the best improvement of F.S.

The piled raft is a geotechnical composite construction consisting of three elements: piles, raft and soil. It is suitable as a foundation for large buildings. This paper presents an analysis of piled raft foundation, including material nonlinearity and soil structure interaction. An efficient computer program in FORTRAN 90 is developed for this analysis. A 20 noded isoparametric brick element has been used to model pile, raft, soil and interface materials. Thin layer interface element has been used to model the contact zone between the pile and soil, and between raft and soil. The behaviour of the piled raft material is simulated by using a linear elastic model. However, the behaviour of soil and interface materials is simulated by an elasto-plastic model by the use of Mohr-Coulomb failure criterion. Some of the variables of a piled-raft system, related to total and differential settlements in sandy soils, have been studied. In these, the length of piles and distance between piles play an effective role in reducing both total and differential settlements of the foundation system. Moreover, increasing the thickness of the raft foundation reduces the effectiveness of additional piles for the purpose of reducing differential settlements.

This research is empirical method for estimating the quantity of seepage under sheet pile wall, which influence on the stability and durability of the sheet pile. Flow net plotted by using Visual Basic Program, which gives greater number of flow lines and equipotential lines. The comparison between the results of visual program and field observations explains excellent agreement. Theoretical models (used to determine quantity of seepage) are divided into three broad categories depending on length of caly layer in the downstream side (L=0,2 and 6 m). For each category, the the models are divided into six parts depending on the depth of penetration of sheet pile (H3=2,4,6,8,10, and 12) for various values of depth of bed rock (H4=24,22,20,18,16,14,12,10,8,6,4, and 2 m) and various values of total head differences (DH=H1-H2=3,4, and 8 M). From the result of the program, at constant (H4), the quantity of seepage decreases with increasing (H3), also at a given (H3), the quantity of seepage increase with increasing (H4) and head difference (DH). A rapid decrease in quantity of seepage with increasing clay layer length(L). The mathematical representation of the series of models are presented by empirical equation resulted from a regression analysis by MS-Statistica. The results of the empirical equation are conservative as compared with the results of the experimental work.

The grouted ground anchor is the most used geotechnical element to transfer the tension load from the superstructure or the soil mass in front of the potential failure surface (active zone) to a deeper, efficient soil layer for its reliability and feasibility. It was originally constructed by inserting the tendon, usually a steel strand, into an already drilled borehole filled with cement grout. It was successfully used in the Cheurfas dam in Algeria in (1934). According to the load transfer mechanism, there are two types of ground anchors: tension-type and compression-type. The names of these two types of anchors refer to the developed stresses in the grouted body. The present work presents a literature survey about the load transfer mechanism for both types of anchors: tension and compression embedded in granular soil. Many factors affecting the load transfer mechanism have been reviewed. The main factor affecting the load transfer mechanism is the confining pressure of the borehole. The recently developed methods of estimating the ultimate pullout capacity of the anchor have been reviewed and discussed.