In-line Directions Research Articles

Time-domain prediction of the coupled cross-flow and in-line vortex-induced vibrations of a flexible cylinder using a wake oscillator model

A numerical study, based on a wake oscillator model, has been performed to determine the three-dimensional vortex-induced vibration (VIV) responses of a flexible cylinder subjected to uniform and non-uniform flows. The coupling equations of the structural oscillator and wake oscillator models in the cross-flow (CF) and in-line (IL) directions, have been solved by employing a standard central finite difference method. The structural displacement, structural frequency, response wave pattern, response trajectory for three different aspect ratios, and four different flow profiles have been compared. As the shear parameter β increases, the maximum RMS values for a certain aspect ratio, in both CF and IL directions, display apparent decreasing tendencies. However, for a certain β, the maximum RMS values in CF and IL directions vary slightly with the increased aspect ratio. The VIV displacements in both CF and IL directions exhibit standing wave and traveling wave behaviors, simultaneously. Further, as the shear parameter β increases, the traveling wave behaviors becomes increasingly dominant. The value of dominant frequency of the CF displacement is always half of that of the IL displacement. The dominant frequency participates in the VIV process at all times, whereas, the other peak frequencies intermittently participate in the VIV process.

Temporal and spatial variations in three-dimensional seismic oceanography

Abstract. Seismic oceanography is a new cross-discipline between geophysics and oceanography that uses seismic reflection data to image and study the oceanic water column. Previous work on seismic oceanography was largely limited to two-dimensional (2D) seismic data and methods. Here we explore and quantify temporal and spatial variations in three-dimensional (3D) seismic oceanography to address whether 3D seismic imaging is meaningful in all directions and how one can take advantage of the variations. From a 3D multichannel seismic survey acquired for oil and gas exploration in the Gulf of Mexico over a 6-month period, a 3D oceanic seismic volume was derived. The 3D seismic images exhibit both temporal and spatial variations of the ocean, and theoretical and data analyses were used to quantify their contribution. Our results suggest that temporal variation is more prominent in the crossline direction than in the inline direction, causing discontinuities in crossline images. However, a series of 3D inline images can be seen as snapshots of the water column at different times, capturing temporal variation of thermohaline structures induced by ocean dynamics. Our findings suggest the potential uses of marine 3D seismic data in studying time-evolving mesoscale ocean dynamics.

A study on performance and flow characteristics of single and double H-type Darrieus turbine for a hydro farm application

The wake of a turbine has a significant effect on the performance of downstream turbine for a hydro farm application's energy conversion in a channel flow. The performance and wake structure of the three-bladed H-type Darrieus turbine with NACA 4418 blade profile were measured in an open water channel using torque sensor and Particle Image Velocimetry (PIV) method and computed by Large Eddy Simulation (LES). Firstly, the torque measurements of the single turbine were completed for a wide range of tip speed ratio (TSR) 0.5–1.4. According to the experimental measurement and LES results, the maximum power coefficient values were obtained as CP = 0.146 and CP = 0.163 at TSR = 1.0, respectively. Then, the velocity field, vorticity pattern, and turbulence kinetic energy in the wake region of the single turbine were qualitatively and quantitatively examined with PIV and CFD at TSR = 1.0 in the horizontal plane. The time-averaged flow field contours and spanwise profiles showed that the PIV results are in good agreement with the LES model to determine the complex flow in the wake of the turbine. The turbine's wake structure exhibited asymmetrical velocity distribution along the downstream due to dynamic stall phenomena and rotation effect. The minimum streamwise velocity values were found to be 73% and 82% of the free-stream velocity at x/D = 6 for PIV and LES results, respectively. However, as the flow moves downstream in the wake, it increased up to 84% and 94% of the free-stream velocity at x/D = 11. The stronger peaks of turbulence is measured behind the turbine at x/D = 0.8 and close to the zero at x/D = 11. Lastly, considering the wake characteristics of a single turbine, the effect of co-/counter-rotating, TSR, and streamwise distance on the performance of a downstream turbine, which was placed in the in-line direction of the upstream turbine, is experimentally and numerically investigated for its use as a hydro farm in a open channel flow. The downstream turbine reached the maximum performance at approximately TSR = 1.0–1.1 for all downstream locations and both rotation direction. In both method, the downstream turbine reached approximately 72% performance of the upstream turbine for the co-rotation at x/D = 11 location, however, this value increased to 78% in the counter-rotation. Due to the asymmetrical wake structure, the results showed that a 6% increase in performance of the downstream turbine can be achieved in the counter-rotating arrangement.

Development of a storage phosphor imaging system for proton pencil beam spot profile determination.

Accurate two-dimensional (2D) profile measurements at submillimeter precision are necessary for proton beam commissioning and periodic quality assurance (QA) purposes and are currently performed at our institution with a commercial scintillation detector (Lynx PT) with limited means for independent checks. The purpose of this work was to create an independent dosimetry system consisting of an in-house optical scanner and a BaFBrI:Eu2+ storage phosphor dosimeter by: (a) determining the optimal settings for the optical scanner, (b) measuring 2D proton spot profiles with the storage phosphors, and (c) comparing them to similar measurements using a commercial scintillation detector. An in-house 2D laboratory optical scanner was constructed and spatially calibrated for accurate 2D photostimulated luminescence (PSL) dosimetry. Square 5×5cm2 BaFBrI:Eu2+ dosimeter samples were uniformly irradiated with line scans performed to determine the physical and electronic scanner settings resulting in the highest signal-to-noise ratios (SNR) at a sub-millimeter spatial resolution. The resultant spatial resolution of the scanner was then quantitatively assessed by measuring (a) line pairs on a standard X-ray lead bar phantom and (b) modulation transfer functions. Following this, 2D proton spot profiles from a Mevion S250i Hyperscan proton unit were obtained at 1, 10, 20, 30, 40, and 50 monitor unit (MU) settings at maximum energy (E0 =227.1MeV) and compared to baseline profiles from a commercial scintillation detector, where 1MU is calibrated to deliver 1Gy absolute proton dose-to-water under reference conditions, that is, 41×41 proton spots uniformly spaced by 0.25cm within a 10×10cm2 square field size at maximum energy (227.1MeV) in water at depth of 5cm at isocenter. The dosimetric system's sensitivities to (a) ±1mm positional shifts and (b) ±0.3mm beam lateral spread changes were quantitatively evaluated through a Gaussian fitting of the crossline and inline plots of the respective artificially shifted beam profiles. The physical scanner settings of (a) Δτ=27ms time interval between data samples, (b) vx =1.235cm/s scanning speed, (c) 1% laser transmission (0.02mW power) and (d) (Δx, Δy)=(0.33, 0.50mm) pixel sizes with electronic settings of (a) 300 microseconds time constant, (b) normal dynamic reserve, (c) 24dB/oct low pass filter slope, and (d) 160Hz chopping frequency resulted in the highest SNR while maintaining sub-millimeter spatial resolution. The BaFBr0.85 I0.15 :Eu2+ storage phosphor dosimeters were linear from 1 to 50MU and their profiles did not saturate up to 150MU. The scanner was able to detect lateral displacements of ±1mm in both the crossline and inline directions and ±0.3mm beam spread changes that were artificially introduced by varying the incident proton energy. Specific to our proton unit, proton energy changes of ±1MeV can also be detected indirectly via beam spread measurements. Our combined dosimetric system including an in-house laboratory optical scanner and reusable BaFBr0.85 I0.15 :Eu2+ storage phosphors demonstrated a sufficient spatial resolution and dosimetric accuracy to support its use as an independent proton spot measurement dosimeter system. Its wide dynamic range allows for other versatile applications such as proton halo measurements.

Illuminating the complex role of the added mass during vortex induced vibration

The role of the added mass coefficient in vortex induced vibration (VIV) of the bluff body is complex and elusive. It is certain that decoding the relationship between the added mass and the vibration pattern will benefit the prediction and prevention of VIV. We present a study on VIV of a long flexible cylinder and forced vibration of a rigid cylinder, in a combination of experimental optical measurements and high-fidelity numerical simulation. We focus on uniform flow over a uniform cylinder at a fixed Reynolds number, Red = 900, but systematically varied the motion amplitude in the in-line (Axd) and cross-flow direction (Ayd), as well as the phase angle (θ) between the motions. We show that θ∈[π2,3π2] is associated with negative added mass coefficients in the cross-flow direction (Cmy < 0), and there is a strong correlation between the vortex shedding mode of “2P” or “P+S” and Cmy < 0.

How Wavelike Bumps Mitigate the Vortex-induced Vibration of a Drilling Riser

In this paper, computational fluid dynamics is used to study how wavelike bumps influence the suppression of drilling-riser vortex-induced vibration (VIV). The numerical model involves two-dimensional unsteady incompressible turbulent flow around a cylinder, with the flow characteristics regarded as being constant. The results show that wavelike bumps are effective in mitigating the VIV, but the degree of mitigation does not increase indefinitely with the number of bumps. The mitigation is greatest with either 5 or 7 wavelike bumps, reducing the vibration amplitudes of the cylinder in the in-line and cross-flow directions to negligible levels. To know how equipping a circular cylinder with wavelike bumps affected its VIV response, cases with wavelike bumps of 1, 3, 5, 7, 9, and 11 are studied.

Solid-structure impact pattern of a vortex-induced oscillating flexible pipeline in the vicinity of a bottom wall boundary

The vortex-induced vibration and solid-structure impact of a neutrally buoyant horizontal flexible pipe in the vicinity of a bottom wall boundary are experimentally investigated in a water flume. The pipe with an aspect ratio of 87 is arranged with an oblique angle of 30° and an initial gap-to-diameter ratio of 0.5. A non-intrusive measurement with two high-speed cameras is employed to simultaneously capture the spatial-temporal vibration displacements in both inline and crossflow directions, and the pipe-wall impact process in the reduced normal velocity range of 3.40–14.43 with a maximum Reynolds number of 2780. Experimental results highlight the new pipe equilibrium profiles deviating away from the bottom boundary due to the wall proximity and wall collision. The occurrence of wall-impact is determined by whether the crossflow amplitude is larger or equal to the summation of the new equilibrium position and initial gap. The observed five distinct solid-pipe impact patterns as well as the location and length of the impacting segments are closely associated with the dominant response mode and the space-varying response amplitude. Particularly, the response mode competition contributes to the spatial shift of impacting position over time.

Flow-induced vibrations of a square prism free to oscillate in the cross-flow and inline directions

Abstract

A numerical study on the flow-induced vibrations of flexible cylinders attached with fixed short fairings

Fairings have been used to suppress the vortex-induced vibrations(VIV) of deep water cylinders in the offshore and marine engineering applications. When properly functioning, they can reduce both the cylinder oscillation amplitude in the cross-flow direction and the fluid drag force in the in-line direction. Plenty research reports can be found on the rigid cylinder VIV suppression performances of fairings while very few research work discuss their VIV suppression performances on flexible cylinders. In the present work, a self-developed high-resolution fluid–structure interaction code based on the computational fluid dynamics is used to simulate the flexible cylinder responses attached with differently covered fixed short fairings. The Reynolds number based on the incoming velocity and the bluff body diameter is 1.68×104. The short fairings are found not to induce strong galloping oscillations in the flexible cylinders while the galloping is prominent in the rigid cylinder cases at large reduced velocities. The different short fairing setups are found to influence the local fluid–structure energy transport distributions and the travelling wave directions in the flexible cylinder responses, which eventually influences the flexible cylinder oscillation amplitude distributions, response frequencies and mode orders.

Flow-induced vibration of high-mass ratio isolated and tandem flexible cylinders with fixed boundary conditions

Flow-induced vibration of a flexible cylinder placed in the wake of a stationary rigid cylinder is studied, experimentally. The flexible cylinder with an aspect ratio of 47 and a mass ratio of 120 was held fixed at both ends and placed horizontally in the wake of the upstream rigid cylinder in the test-section of a subsonic wind tunnel. The dynamic response of the cylinder is studied in both the streamwise (inline) and transverse (crossflow) directions for center-to-center spacing range from 3 to 9 times the diameter of the cylinder. Amplitudes and frequencies of oscillation, as well as flow forces on the cylinder are studied in the reduced velocity range of U∗=3.3−50.3 and the Reynolds number range of Re=3,057–46,536. The dynamic response observed in this study are presumably the result of two combined phenomena of vortex-induced vibration and wake-interference galloping. Despite the high-mass ratio of the flexible cylinder, higher modes of vibrations up to the fifth mode are excited in both the crossflow and inline directions, owing to the high-flexibility of the cylinder. Both odd and even modes are excited in the crossflow and inline directions. As the separation distance between the cylinders increases, the amplitudes of oscillation increase over a wider range of reduced velocities. Spanwise trajectories of motion are studied and regions along the length of the cylinder that are excited or damped by the flow, i.e., regions with positive and negative flow force coefficient in phase with velocity, are identified.

Numerical investigation on effect of internal flow on vortex-induced vibration dynamics of a full-scale mining riser

The dynamics of a full-scale pipe conveying fluid inside is investigated based on the finite element method (FEM). During the numerical simulation, the Euler–Bernoulli beam equations are used to model the motion of the full-scale pipe while the effect of internal flow is considered. And the semi-empirical time-domain model is applied to simulate the external hydrodynamic forces exerted on the pipe. Then the typical vortex-induced vibration (VIV) characteristics of the full-scale pipe considering both internal and external flows are analyzed. The results show that with the increase of the internal flow velocity, the natural frequencies of the full-scale pipe decrease and the in-line (IL) and cross-flow (CF) dominating modes are increased. Furthermore, the dominating frequencies in both IL and CF directions are not notably changed. And the IL and CF root-mean-square (RMS) values of amplitudes fluctuate at around the stable values due to the stable external hydrodynamic forces. It should be noticed that the IL and CF RMS strain values of the full-scale pipe are increased, especially for high external and internal flow velocities. The maximal RMS strain values in both IL and CF directions appear next to the pipe top, which could have an influence on the motion of the ship on the sea surface.

Vortex-induced vibration of a cylinder with nonlinear energy sink (NES) at low Reynolds number

Vortex-induced vibration (VIV) is a fluid structure interaction phenomena that can lead to the fatigue failure of high-rise structures. To study the basic principles and method of VIV suppression for a cylinder structure, a two-dimensional simulation model using a cylinder with two degrees of freedom in-line and cross-flow directions is presented herewith. A nonlinear energy sink is added to cylinder structures to assess its impact on vibration suppression. As a result, this study aims to investigate the VIV of cylinder under the action of the NES at low Reynolds numbers. The accuracy of the simulation model is verified by the comparison with the experimental results. Particularly, the VIV response is investigated with different mass ratio $$\beta$$ between the NES and cylinder (namely $$\beta$$ of 0.15, 0.2 and 0.3) at Re = 100 in air environment by analyzing the vibration response, phase diagram, time–frequency and vorticity contours of cylinder and NES oscillator. Three distinct function modes of NES for selected mass ratio $$\beta$$ are also observed. The results indicate that the NES can change between resonance capture states, from weak to strong, when the mass ratio $$\beta$$ increases to a defined value. In this case, the main vibration frequency of the cylinder varies over time, and the motion is in the chaotic state. The NES can also effectively reduce the vibration amplitude in both the in-flow and cross-flow directions.

Numerical simulation of flow induced vibration of two rigidly connected cylinders in different arrangements

ABSTRACT The flow induced vibration (FIV) responses of two rigidly connected cylinders at different staggered configurations have been studied numerically. The two cylinders, with an equal diameter of D, can oscillate in both cross-flow (CF) and in-line (IL) directions simultaneously. The center-to-center spacing between the two cylinders has been fixed at 4D. The numerical results demonstrate that as the angle of incidence (α) increases, the wake interference between the two cylinders becomes weak. For α with small values, the FIV responses are dominated by the galloping vibration and the vortex-induced vibration (VIV) simultaneously. However, for α with large values, the FIV responses are obviously dominated by the VIV. As α increases, the maximum vibration amplitude follows a downward trend and the total mean drag coefficient tends to decrease. Furthermore, the vortex shedding flow pattern has apparently different modes for varying α.

Laboratory measurements of the effects of interlaminar slip on vortex-induced vibrations of the unbonded umbilical

Laboratory tests were performed to investigate the influence of interlaminar slip on the vortex-induced vibrations (VIV) of the unbonded umbilicals. Two types of umbilical models with the same size were fabricated by using an acrylic tube enclosing seven-core spiral copper cable, in which the unbonded umbilical contains relative slip between its tube and cable, and the interior structure of the bonded one was fixed as a contrast. Both umbilical models under a same top tension were excited respectively in a flume with current velocity varying from 0.1 m/s to 0.7 m/s. Fiber Bragg Grating (FBG) sensors were employed to measure the VIV response in both cross-flow (CF) and in-line (IL) directions. Experimental results confirm that the unbonded umbilical is more susceptive to the reduced velocity in terms of displacement, frequency and trajectory, which is attributed to the nonlinear variation in bending stiffness resulting from the relative slip. Furthermore, the onset of lock-in region for the unbonded model occurs at a lower velocity than that for the bonded model, but with a similar width of lock-in region. Although VIV displacement in the mode transition is relatively small, the interlaminar slip still works due to the influence of its high frequency.

Experimental study on wave isolation performance of periodic barriers

A wave barrier—combining the advantages of trench-type wave barriers and metamaterials—is made by infilling the trench-type wave barrier with metamaterials. In this research, a series of full-scale field experiments are conducted to investigate the screening effectiveness of both empty trench and periodic barriers. The precast unit cells of periodic barriers are arranged to form one long barrier with a length of 2.44 m, one short barrier with a length of 1.22 m, or two short barriers with a length of 1.22 m to examine the influence of barrier length and the number of unit cells on the wave isolation performance. The state-of-the-art high-force triaxial (T-Rex) shaker truck is used to generate excitation in the vertical, horizontal inline, and horizontal crossline directions. Three excitation inputs are tested, including fix-frequency harmonic excitations, frequency sweeping excitations, and the earthquake excitation. For each test, a benchmark test is conducted prior to the barrier installation. The ground surface responses at each geophone location are recorded in all three directions. The normalized response of each point, the responses in front of the barrier and behind the barrier, and the frequency response function (FRF) are presented in detail. Test results show that the various excitation inputs lead to similar results. The performance of the periodic barrier is found to depend on the excitation directions due to the dominate wave form. By comparing the FRF between the benchmark case and the case with periodic barriers, the screening effectiveness of periodic barriers can be identified in some frequency ranges, which are expected to be the frequency band gaps of the periodic barriers.

Vortex-Induced Vibrations of a square prism free to oscillate in the inline direction

We study the response of a prism placed in flow and free to oscillate in the direction of flow (the inline direction) for different possible angles of attack. The tests were conducted in a water tunnel for a range of reduced velocities of 2.4 <U* < 5.8 and Reynolds numbers of 757 <Re < 1900, and over angles of attack of 0° ≤α≤ 45°, where α= 0° corresponded to the case where one of the square’s sides was perpendicular to the incoming flow. We observed Vortex-Induced Vibrations in the inline direction for angles of attack of α= 0°, 2.5°, 5°, 7.5°, and we showed that lock-in has occurred in the cases where oscillations are observed, by showing that the shedding frequency and the oscillation frequency were equal in this range. Throughout the lock-in range, the fluctuating force and the displacement remained in phase as well. The width of the lock-in range and the maximum amplitude of oscillations decreased with increasing angles of attack, and no oscillations were observed for α > 7.5°. The wake structures were found to be predominantly symmetric for α= 0°, and transitioned toward asymmetry with increasing α. By calculating the ratio of the fluctuating lift force to the fluctuating drag force, we quantified how the asymmetry in fluid forces increased with increasing both the angle of attack and the reduced velocity. We also showed how for larger angles of attack where oscillations were not observed, giving an initial disturbance to the prism resulted in formation of vortices for only few cycles and the prism’s oscillations decayed and were damped by the fluid forces.

Experimental study on elastic behaviors of two tandem risers in constant flow

Multiple pipes bundled with a certain distance are used for deep ocean development for such as lifting seafloor massive sulfides (SMS), pumping up a large amount of cooling water for onboard natural gas liquefaction, and production of oil/gas. To understand the vortex-induced phenomenon of fluids and the structural mutual interference among pipes in a steady flow, a towing tank test using a model of two vertical elastic pipes in tandem is performed. The parameters of this test are: the distance between the two pipes, the incident angle of crossflow with the inline direction of the pipes, the flow velocity (towing speed), and the boundary conditions of the tops of the pipes. The two horizontal accelerations of the towing direction and perpendicular direction are measured with synchronization. Then, the motion of the two pipes in each direction was measured, and the influence of the distance between the two pipes on the motion from the amplitude and phase information was analyzed. The results are investigated relatively in detail about the tandem arrangements of the two pipes to the incident flow. It is found that the major motion pattern of the two pipes in the tandem case is a rotational motion around the midpoint of two pipes.

Characterization and dosimetry of photon multileaf collimated electron beams using Gafchromic film measurements

Previous studies indicated that clinical electron beam shaping involving a photon multileaf collimator (MLC) can be achieved. It is usually applied in Modulated Electron Radiation Therapy or MERT. This technique requires accurate clinical electron beam characterization before implementation in advanced treatment planning techniques. This study presents the dosimetric characterization of clinical electron beams shaped by an Elekta Synergy linear accelerator equipped with a 160 leaf Agility MLC for electron beams energies of 4, 6, 8, 10, 12, and 15 MeV. Dosimetric parameters of regular fields ranging from 1 × 1 to 20 × 20 cm2 were investigated to reflect those fields used in electron beam therapy at two source-to-surface distances (SSD) of 60 and 70 cm. Percent depth doses (PDDs), in-line, and cross-line beam profiles and output factors (OFs) were measured. Beam profiles were found to be wider compared to electron beams collimated by standard applicators. Penumbrae formed by the pMLC in cross-line direction was wider compared to penumbrae formed by the back-up jaws in in-line direction. The jaws are located below the MLC and are closer to the plane of measurement. The beams produced at 60 cm SSD also produced smaller penumbra. Beam spacing was also investigated and a clinical case was investigated for total scalp treatment in a head phantom and measured with Gafchromic film. The clinical investigation result showed good dose distribution over the therapeutic region and the treatment time is 3 times faster compared to the use of standard applicators for field greater than 5 × 5 cm2. All the measurements for beam dosimetric characterization were performed using Gafchromic EBT3 film and solid phantoms.

Time-domain analysis of vortex-induced vibration of a flexible mining riser transporting flow with various velocities and densities

Vortex-induced vibration (VIV) can be inevitably encountered in deep ocean mining. As the internal flow is transported axially in the flexible riser, complicated VIV dynamics occurs undergoing both the internal and external flows. Therefore, the object here is to explore the effect of the internal flow with different velocities and densities on VIV response under various uniform current. In this study, a semi-empirical time domain prediction method for VIV dynamics of flexible risers considering both internal and external flows is introduced and adopted. The governing equations are discretized and solved by using finite element method. Firstly, validations are made for VIV without internal flow based on the numerical results and experimental data. Comparisons prove that the simulation could reproduce the VIV dynamics of a flexible riser. Then with the increase of the internal flow velocities and densities, the effect of the internal flow on VIV response is examined. It is found that the dominating frequency and the root mean square (RMS) displacement in both in-line (IL) and cross-flow (CF) directions are notably influenced by the internal flow velocity and density. Besides, the drag coefficient and IL mean deflection are detected magnified while the internal flow velocity and density are increased under different external flow velocities. It should be noted that the change of the internal flow velocity and density could trigger new mode response of the flexible riser, leading to mode transition for the IL and CF dominating modes. In addition, VIV dynamics shows a similar changing trend with the increase of the internal flow velocity and density when the flexible fluid-conveying riser is subjected to different external flow velocities.

Environmental hazard assessment for ground failure in Jeddah city, western Saudi Arabia, through cross-hole seismic testing

The environmental threats of soil subsistence in Jeddah city have been assessed using cross-hole seismic testing. These threats affect the state of health of roads, buildings, near-surface foundations ensuring a reliable and economic infrastructure design, as unanticipated site conditions can cause significant traffic problems, soil subsidence, and structural collapse. Cross-hole seismic testing is of utmost importance in determining velocity profiles of P- and S-waves for environmental hazard assessment. These velocity profiles are required to calculate the geotechnical parameters of soil nearby important structures. A cross hole seismic survey was conducted at boreholes close to Jeddah desalination plant. A sledgehammer horizontally striking a wooden plate was used to generate S-waves polarized in the crossline and inline directions. A vertical hammer hitting a metal plate to generate the P-wave then the first break arrival times were inverted for the P- and S-wave velocity structure estimation. The equipment and procedures comply with the American Society for Testing and Materials (ASTM) D 4428/D 4428M-91 standard test method for cross-hole seismic testing. The estimated velocities were utilized to calculate the elastic moduli, geotechnical parameters and density variations within the mapped area. These parameters agree with the lithological variations of near- surface sediments from borehole logs. Finally, the study area illustrated soft, fractured, and poorly graded sediments, which, in turn, require special treatment from engineering point of view before establishing the important facilities in the area. These results are highly recommended and have to be considered to mitigate the environmental hazards in Jeddah city.