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The currently in use fluid loss model (American Petroleum Institute (API)) was developed using the Darcy relationship and assuming that there is no changes in the permeability, solid content in the filter cake and filter cake thickness during the 30 min of fluid loss. Hence, in the current API model, the fluid loss is directly propositional to the square-root of time. In this study, a new proposed hyperbolic fluid loss model has been developed based on a time dependent variation in the filter cake properties. Also, the new proposed model has the power to quantify the short-term and long-term fluid losses (more than 30 min). Moreover, the new model has a limit on the total fluid loss compared to the current API model that shows an infinite fluid loss with time. The new model parameters are related to the applied pressure and temperature using nonlinear power models. The new model predictions are verified with the fluid loss results reported in the literature (225 °C and 300 psi) and tests performed in the laboratory at high pressure and high temperature on bentonite drilling muds during this study. The laboratory tests are both limited to 2% and 8% (by weight) bentonite drilling muds at 100 °C and 100 psi (689.5 kPa) up to 420 min (7 hrs) till the end of the fluid loss. The new model predicts the experimental results on maximum fluid loss and changes in the filter cake porosity, permeability, solid content, and thickness with time, pressure and temperature very well.

In the presence of harsh economic conditions, conducting laboratory experiments in a wide anticipated area to determine soil properties for any purpose or task within a city is unachievable. Hence, this work is focused on incorporating the existing record data of 56 distinct soil samples acquired from different pits of Kirkuk city utilizing spatial analysis described by inverse distance weighted (IDW) and Kriging methodologies. The incorporated constituents were principally categorized into basic soil characteristics such as clay, silt, sand, and gravel contents and various soil parameters such as initial void ratio (e o), angle of internal friction (ϕ), cohesion (c), and optimum soil moisture content. Moreover, quantitative approaches such as geotechnical parameters association, linear single, and linear multi-regression models were used. Significant discrepancies in both approaches are readily obvious in the third to fifth zones, indicating that IDW and Kriging processes describe the distribution of sand in Kirkuk city differently. Furthermore, linear multi-regression model between basic and investigated soil parameters show good to excellent and very good to excellent degrees of correlation, with multiple R values in the range of (0.77–0.97) and (0.86–0.98), respectively.

With the growth in construction along the coastal regions, ports and offshore deepwater sea beds, ultra soft clay soils are encountered and are affecting the performance of the pipelines and other anchor systems placed in it. In this study, untreated and treated ultra-soft clay soils shear strengths were quantified using the modified vane shear device and correlated the shear strength to the CIGMAT miniature penetrometer penetration and electrical resisitivity. The ultra-soft clay soils were prepared by varying the bentonite content from 2 to 10%. The soil with 10% bentonite was treated with 2–10% lime and with 1–10% polymer separately to enhance the shear strength. The shear strength, pH, CIGMAT miniature penetrometer and electrical resistivity were used to characterize the untreated and treated ultra-soft clay soils. Untreated soft soil strength varied from 0.01 to 0.17 kPa when the bentonite content in the ultra-soft clay soil was increased from 2 to 10%. With 2% lime treatment the shear strength of 10% bentonite soil was increased to 0.27 kPa. Adding 10% lime to the 10% bentonite ultra-soft soil reduced the shear strength to 0.15 kPa. With 10% polymer treatment, the shear strength was increased by 45 times to 6.8 kPa for the 10% bentonite ultra-soft soil. The CIGMAT miniature penetrometer penetration varied linearly with the shear strength of the untreated ultra-soft clay soils and treated ultra-soft clay soils with 10% bentonite. pH was almost constant for untreated ultra-soft clay soils while it increased by 22% and 35% for the 10% lime and 10% polymer treated ultra-soft clay soilss respectively. Relative electrical resistivity decreased by 246% when the bentonite content was increased from 2 to 10% in the ultra-soft clay soils. Addition of 10% of lime to the ultra-soft clay soil with 10% of bentonite content decreased the relative electrical resistivity by 171%. Addition of 10% of polymer to the ultra-soft clay soil with 10% of bentonite content reduced the relative electrical resistivity by 545%. Power law, linear and Vipulanandan correlation models were used to predict the shear strength-resistivity relationship for the untreated, lime-treated and polymer-treated ultra-soft clay soils respectively. In addition, linear model was used to predict the water content relationship with electrical resistivity for the untreated and treated ultra-soft clay soils. The CIGMAT miniature penetrometer was modeled using 3-D axisymmetric finite element method, which predicted the penetration of CIGMAT penetrometer that agreed well with the experimental results of the untreated and treated ultra-soft clay soils. The CIGMAT miniature penetrometer penetration and the electrical resisitivity monitoring are two non-destructive methods that can be easily adopted in the field and the property correlations can be used to determine the shear strength of the ultra-soft caly soils in the field.

Advanced developed technologies associated with people demands have caused production and expansion of different local wastes where the process of managing such waste becomes a real need for controlling the pollution risk. One of the procedures for recycling can be made through using local wastes in permeability control for sandy soil since the soil permeability plays a crucial function on the water drainage, pore water pressure buildup and dissipation, and ground movement for saturated sand during and after earthquake occurrences. In addition, any economical mixture should maintain hydraulic constraints for practice use. In this study, a laboratory experiment was prepared to perform tests for estimating the water movements and permeability in a pure sand column and treated sandy soil with different locally waste materials including plastic, glass, rubber, and aluminum. In addition, a numerical investigation including finite element method has been adopted to verify the experimental procedure. It was shown that the permeability could be controlled to different rates using these local wastes.

In the sense of challenging economic situation, it is difficult to perform laboratory tests in a whole intended area to define the soil characteristics for whatever task or situation within an entire city. Hence, this study has used the spatial analysis through applying the inverse distance weighted (IDW) technique to integrate with the available data for 56 different soil samples collected from various depths of Kirkuk city. The studied characteristics were mainly classified to physical soil properties included gravel, sand, silt, and clay contents with chemical soil properties included organic and gypsum contents, pH content, sulfur trioxide, and total dissolved solids (TDS) content. Moreover, statistical investigations such as physico-chemical correlation, linear single and linear multi regression models have been applied. The results of this study have focused on constructing thematic digital maps for visualizing different physical and chemical characteristics of Kirkuk soil. In statistical analysis, negative linear correlations are obtained from the relation between the values of the pH, gypsum, organic, and SO3 contents with the increase of the gravel content, whereas a positive linear correlation is attained for the values of TDS content with the increase of the gravel content. Furthermore, the proposed linear multi regression model predicts the pH values reasonably where most of the values were close to the equality line. The obtained digital maps accompanied with the statistical models will provide comprehensive spatial, agricultural, chemical and mechanical visualizations of the nature and morphology of the soils in Kirkuk city.

The impacts of up to 3% salt contamination and temperature in the range of 25°C to 75°C on the bentonite drilling muds were investigated. The rheological and resistivity properties of 2% an...

An assessment was carried out of the relationship between the Corona Virus (covid-19) and the spread across Iraq of various heavy metal contaminations. At the onset, all the confirmed, recovered an...

In this study, the strong and weak forms of Darcy flow equation has been derived. The final obtained equation is Laplace partial differential equation. For total head evaluation, Laplace equation is solved using exact solution depending on Fourier series and numerical solution depending on finite element method. A computer program has been developed in MATLAB program to solve the Laplace equation using both exact and finite element solutions and the seepage of water under sheet pile is taken as a case study. Different number of points and nodes has been selected for the two methods. It is shown that both exact and finite element solutions have a good match in distribution for the study area especially when the Fourier points are increased.

In this study, the untreated and treated grout soft clay soil behaviors have been investigated using both consolidation and unconfined compression stress laboratory tests. Soft soil samples have been obtained from the central zone of Kirkuk city, where this soil has been treated with different schemes of cement grout and cured for two weeks. The used grout has water to the cement of 5 where this ratio has been determined after several laboratory trials. Two nonlinear mathematical models, including second-order polynomial and p-q models, have been utilized to predict the void ratio-vertical effective stress and unconfined compression stress relationships. As the soft soil was treated with five grouts, the void ratio has decreased by 30.6%, and the unconfined compressive strength has increased by 97%. In addition, both used models have good agreements with the experimental data where the maximum recorded R2 for nonlinear polynomial and p-q models were 0.9991 and 0.973, respectively.

The characterization of ultra-soft clayey soil exhibits extreme challenges due to low shear strength of such material. Hence, inspecting the non-destructive electrical impedance behavior of untreated and treated ultra-soft clayey soils gains more attention. Both shear strength and electrical impedance were measured experimentally for both untreated and treated ultra-soft clayey soils. The shear strength of untreated ultra-soft clayey soil reached 0.17 kPa for 10% bentonite content, while the shear strengths increased to 0.27 kPa and 6.7 kPa for 10% bentonite content treated with 2% lime and 10% polymer, respectively. The electrical impedance of the ultra-soft clayey soil has shown a significant decrease from 1.6 kΩ to 0.607 kΩ when the bentonite content increased from 2% to 10% at a frequency of 300 kHz. The 10% lime and 10% polymer treatments have decreased the electrical impedances of ultra-soft clayey soil with 10% bentonite from 0.607 kΩ to 0.12 kΩ and 0.176 kΩ, respectively, at a frequency of 300 kHz. A new mathematical model has been accordingly proposed to model the non-destructive electrical impedance-frequency relationship for both untreated and treated ultra-soft clayey soils. The new model has shown a good agreement with experimental data with coefficient of determination (R2) up to 0.99 and root mean square error (RMSE) of 0.007 kΩ.

Several engineering attributes, such as soil strength and deformability, are very significant and are regarded as the basis of any sort of foundation design. In determining the vibration extent depending on the used soil numerical models, soil characteristics represented by the shear wave velocity, cohesion, angle of internal friction and Poisson’s ratio are crucial. Different kinds of parameters are identified in various used manuals in numerical modelling. The outputs of these numerical programs are commonly dependent on the input parameters. Thus, in the analysis of any geotechnical problem, the correct selection of rigorous values of the engineering properties of the soil is extremely serious. In this study, a set of field data for Standard Penetration Test (SPT) values has been collected from more than twenty different places in Kirkuk city. In addition, using the random number generation method, several empirical relationships of various soil properties have been advanced in terms of the spectrum of the collected SPT values. The functional benefit of the relationships developed can be used to validate the observed experimental geotechnical data integrated in the architecture of the different civil engineering ventures. As a result, for the SPT-N values ranged from 4 to 44, the predicted soil cohesion and angle of internal of friction increased from 17 kPa to 281 kPa and 4° to 38° respectively. As an overall evaluation, the shear wave velocity ranged from 72 (m/s) to 367 (m/s) whereas the field and predicted UCS varied from 60 kPa to 320 kPa and 54 kPa to 400 kPa respectively.

The effective stress method is developed to predict the axial capacity of piles in clay. The effective stress state changes due to the resulting pore pressure change and therefore, the strength and stiffness of the soil will change. In this work, the finite element method is utilized as a tool for the analysis of pile-soil systems in undrained condition. The computer program CRISP was developed to suit the problem requirements. CRISP uses the finite element technique and allows predictions to be made of ground deformation using critical state theories. Eight-node isoparametric element was added to the program in addition to the slip element. A pile loading problem was solved in which the pile-soil system is analyzed in undrained condition. The pile is modelled as elastic-plastic material, while the soil is assumed to follow the modified Cam clay model. During undrained loading condition, the settlement values increase by 22% when slip elements are used. The surface settlement increases by about three times when the load is doubled and the surface settlement at all points increases when using slip elements due to the mode of motion which allows smooth movement of the adjacent soil with respect to the pile. The vertical displacement increases as the distance decreases from the pile and negligible values are obtained beyond 10D (where D is the pile diameter) from the center of the pile and these values are slightly increased when slip elements are used. The vertical effective stress along a section at a distance D from the pile center is approximately the same for all load increments and lower values of effective vertical stress can be obtained when slip elements are used.

In this study, an experimental and numerical investigation of Kirkuk real field soil treated with waste tire has been examined. Field soil samples from Kirkuk city have been collected and tested experimentally to evaluate the basic soil properties. The field soil has been treated with waste shredded tires and up to 10%. A series of direct shear tests under different normal stresses and unconfined compression tests with two different rates have been performed on both untreated and waste tire treated soils. For the untreated soil, the maximum shear stress measured by the direct shear test increased by 150% when the normal shear stress increased from 50 kPa to 150 kPa. For the 5% and 10% waste tire treated soils, the maximum shear stresses measured by the direct shear test increased by 110% and 105% when the normal stress increased from 50 kPa to 150 kPa respectively. The peak uniaxial stress measured by the unconfined compression test increased by 83% and 98% as the waste tire treatment increased from 0% to 10% for both testing rates of 0.125 mm/min and 0.25 mm/min respectively. Finally, finite element method using three different models represented by elastic, hyperbolic and Mohr-Coulomb elastic-plastic models have been used to model unconfined compression tests for both untreated and 10% waste tire treated soils. For both untreated and waste tire treated soils, the elastic model over predicted the shear stress versus shear strain relationship whereas the elastic-plastic model had a very good agreement with the experimental data. However, the hyperbolic model had a good prediction for the initial part of the shear stress versus shear strain relationship for both untreated and waste tire treated soils with an overestimation for the second part of the experimental data.

In this study, large-scale physical models with dimensions of (0.9m * 0.9m * 0.55m) have been designed and constructed to investigate the behavior of strip footing in reinforced sandy soil with multi-geogrid layers under inclined and eccentric loading conditions. The effect of several parameters such as geogrid layers (N), soil relative density (RD), depth of the topmost geogrid layer (U/B), load inclination angle () and load eccentricity ratio (e/B) on the bearing capacity ratio (BCR) of reinforced soil have been investigated through 120 experimental tests. As the number of the geogrid layers increased from 0 to 4, the BCR increased by 255% for 15o load inclination angle and by 470% for 0.05 load eccentricity ratio in 60% RD. When the RD of the soil increased from 60% to 80%, the average decreases in horizontal displacement and footing tilting angle were about 35% and 21% respectively. Hyperbolic analytical model was used to predict the relationships of most of the studied parameters. However, p-q analytical model was suggested to model the relationship between the BCR versus U/B. Both suggested models (hyperbolic and p-q) were in a very good agreement with the experimental results.

Abstract Drilling muds are used in oil, gas, and geothermal well drilling, and fluid loss and filter cake formation are critical issues related to successful operations. Also, the filter cake formation and fluid loss are affected by high pressure and high temperature (HPHT) in the borehole. Rate and total fluid loss from drilling mud can affect the performance of the drilling mud and well safety. Hence, it is critical to quantify not only the rate of fluid loss process but also the changes in the filter cake formation during the fluid loss process. Past studies have assumed that the permeability and solid fraction in the filter cake remained unchanged during the formation of the cake and the fluid loss was directly propositional to the square-root of time (API Model). In the experimental part of this study, fluid loss tests were performed for 420 minutes on 2 percent and 8 percent bentonite drilling muds at 100 psig pressure and 100°C temperature. A new kinetic hyperbolic model was developed based on satisfying the basic governing conditions during fluid loss and assuming that the permeability and solid content during the filter cake formation changes with time, temperature and pressure. The new kinetic model was verified with results from various HPHT fluid loss studies reported in the literature and HPHT experiments performed during this study. The new kinetic model prediction was also compared to the API model, and it predicted both short-term (up to 30 minutes) and longterm fluid losses very well. Hence, the new kinetic model can be used to better model the filter cake formation and filter loss in real time as functions of changes in permeability and solid content in the filter cake.