The aim of the current study is to determine the elastic properties of carbonate rocks using ultrasonic method. Forty rock samples of Anah formation were collected at different depths from four wells drilled at the study area . The relationship between wave velocities and elastic properties of rocks was defined. Regression analyses to define these relations were applied. The results indicate that the elastic properties of the rocks show a linear relationship with both P- and S-wave velocities. The best relationship was obtained between both Young's modulus and Shear modulus with Vs in the determination of the coefficient ( R2 ), with values of 0.91 and 0.94, respectively. Bulk modulus and Lame’s constant were better correlated with Vp than with Vs in the determination of R2,with values of 0.92 and 0.83, respectively. Poisson’s ratio showed a good correlation using the ratio of Vp/Vs in the determination of R2, with a value of 0.81. The main output of this study shows that the ultrasonic method is a useful tool for the prediction of the elastic dynamic properties of sample rocks and that it can be used as an economical , simple and non- destructive method, especially for engineering purposes.
The aim of this paper is to determine the capability of the ultrasonic technique to predicate and evaluate some elastic and geotechnical properties within sand stone layers. For this purpose, 15 rock samples were collected from Tanjero Formation that is exposed in Dokan area, northeastern Iraq. Elastic wave velocities (Vp and Vs) and density (P) values for rock samples were determined by applying laboratory testing. From Vp, Vs, and density values, the porosity, elastic modulus, and some geotechnical parameters were calculated. The relationship between P wave velocity and elastic properties of samples was derived. Empirical equations were obtained by applying the regression analyses between Vp and the measured elastic properties. Good correlations were found, which may supply a good estimation of elastic properties from velocity information related to the geological setting of the area. This work confirmed the capability of the ultrasonic technique for predicating the elastic properties of rocks.
The objective of the present research is to confirm the possibility of ultrasonic methods as geophysical tool for the estimating of geotechnical parameters for engineering purposes. Thirty seven (37) rock samples were collected at different depths of borehole drilled at the study area, and both primary and secondary waves velocity (Vp and Vs) were measured in laboratory. To evaluate the rock competence as foundation material for engineering works, some important geotechnical parameters including Poisson’s ratio(σ), Stress Ratio(Si), Material index(Im), Concentration index(Ic), and Density gradient( Di) were calculated. The obtained results demonstrate that the first surface layer is characterized by incompetent to fairly competent materials, the second layer (Anah Formation) is characterized by alternation of the moderately competent ( limestone) with thin incompetent (coralline limestone) layer, while the third layer (Baba Formation ) which composed of dolamatic limestone is characterized by good geotechnical parameters, reflect good competent rocks representing more suitable rocks as foundation layer for civil engineering constructions at the investigated site. The results also confirm the efficiency of ultrasonic method in estimating and assessing the geotechnical parameters of rock samples in pre-construction studies.
The aim of the current research is to use the ultrasonic wave velocity for assessment of rock competence for pre-foundation study at engineering site near Rawa city. Thirty seven (37) rock samples were gathered from different depths of well drilled at the site. Both compressional and shear waves velocity (Vp and Vs) were measured in the laboratory. To assess the competency of rocks as foundation materials, some geotechnical properties include Poisson’s ratio(σ), Effective angle of internal friction (ϕ), Material index(Im), and Coefficient of lateral earth pressure at rest (Ko) were calculated. The results of the study showed that the first layer characterized by incompetent to fairly competent materials, the second layer (Anah Formation) composed of alternation of the moderately competent (limestone) with thin incompetent (fractured coralline limestone) rocks, while the third layer (Baba Formation) which composed of dolamatic limestone characterized by good competent rocks. Depending on above mentioned results, the third layer (Baba Formation) is more suitable as foundation rocks for constructions purposes at the investigated site. The results also confirm that the ultrasonic wave velocity is effective method in evaluating the geotechnical properties of rock in pre-construction works.
An electrical resistivity tomography survey was carried out in Diyala University campus, southern Baqubaa city, Iraq. The main aim of this study is to evaluate the efficiency of electrical resistivity tomography to detect the buried sewage system as well as to assess its environmental impact on the surrounding soil. Six parallel resistivity profiles were carried out at a perpendicular direction to the axis of the sewage system. Two-and three-dimensional geoelectrical models were constructed to determine the distribution of resistivity and its relation with both buried structures and contaminated zones. The results showed an intermediate relative resistivity zone (6-10 Ω.m) and several rounded very low resistivity zones (< 1 Ω.m), identifying the underground sewage system and contaminated soil, respectively. Based on variations in resistivity values, six holes (h1, h2, h3, h4, h5, and h6) were drilled. A total of six soil samples at 1.5m depth (1 sample per hole) were collected for heavy metals concentrations analysis. The results of the chemical analysis showed a higher concentration of heavy metals near the septic system than that the area away from it. Much lower resistivity zones (<1 Ω.m) and the higher concentration of heavy metals observed near septic system indicate the impact of contamination by migration from the septic tank into the nearby soil. The results of this study confirm the efficiency of electrical resistivity tomography for detecting a buried object and mapping contaminated zone for engineering and environmental applications.
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