scholarly journals STABILITY ANALYSIS OF SEAFLOOR FOUNDATIONS

1980 ◽  
Vol 1 (17) ◽  
pp. 109 ◽  
Author(s):  
Tokuo Yamamoto ◽  
Tasumasa Suzuki
Keyword(s):  
Stability Analysis ◽  
Wave Length ◽  
Field Measurements ◽  
Senior Author ◽  
Effective Stresses ◽  
Design Storm ◽  
Storm Waves ◽  
Effective Stress Analysis ◽  
Concrete Blocks ◽  
Wave Induced

Stability analysis of homogeneous and inhomogeneous seabed foundations under attack by storm waves are made by calculating the wave induced effective stresses. Wave induced effective stress analysis of homogeneous seabed is made using the theory previously developed by the senior author which is based on the poro-elastic theory by Biot. Effective stresses in inhomogeneous seabeds induced by waves are calculated by approximating an inhomogeneous bed by many layers of homogeneous soils each of which has different geotechnical properties of soils. A good agreement is obtained between the theory and the pore pressure data in situ field measurements. For a given wave length, it is found that there exists a most unstable thickness of homogeneous seabed when the seabed thickness is one-fifth of the wave length. As a realistic example of an inhomogeneous bed, the effective stresses in a typical seabed formation at the Mississippi Delta area of the Gulf of Mexico under the attack of design storm waves are calculated. The numerical results indicate that the storm waves induce a continuous submarine landslide which extends as deep as 9 m from the mud line. Numerical calculations also indicate that such landslides and liquefaction of seabeds can be prevented by placing a layer of concrete blocks or rubbles on the top of the seabeds.

scholarly journals Development of an analytical model to predict oil reservoirs performance using mechanical waves propagation

2021 ◽  
Author(s):  
Hesham A. Abu Zaid ◽  
◽  
Sherif A. Akl ◽  
Mahmoud Abu El Ela ◽  
Ahmed El-Banbi ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Field Measurements ◽  
Field Trials ◽  
Oil Field ◽  
Reservoir Properties ◽  
Actual Performance ◽  
Reservoir Performance ◽  
Mechanical Waves ◽  
Incremental Oil Recovery ◽  
Wave Induced

The mechanical waves have been used as an unconventional enhanced oil recovery technique. It has been tested in many laboratory experiments as well as several field trials. This paper presents a robust forecasting model that can be used as an effective tool to predict the reservoir performance while applying seismic EOR technique. This model is developed by extending the wave induced fluid flow theory to account for the change in the reservoir characteristics as a result of wave application. A MATLAB program was developed based on the modified theory. The wave’s intensity, pressure, and energy dissipation spatial distributions are calculated. The portion of energy converted into thermal energy in the reservoir is assessed. The changes in reservoir properties due to temperature and pressure changes are considered. The incremental oil recovery and reduction in water production as a result of wave application are then calculated. The developed model was validated against actual performance of Liaohe oil field. The model results show that the wave application increases oil production from 33 to 47 ton/day and decreases water-oil ratio from 68 to 48%, which is close to the field measurements. A parametric analysis is performed to identify the important parameters that affect reservoir performance under seismic EOR. In addition, the study determines the optimum ranges of reservoir properties where this technique is most beneficial.

scholarly journals WAVE-INDUCED SHOCK PRESSURES UNDER REAL SEA STATE CONDITIONS

1988 ◽  
Vol 1 (21) ◽  
pp. 173 ◽  
Author(s):  
Joachim Grune
Keyword(s):  
Peak Pressure ◽  
Field Measurements ◽  
Breaking Waves ◽  
Sea State ◽  
Pressure Time ◽  
Time Histories ◽  
Wave Induced

This paper deals with a study on shock pressures, which occur on sloping seadykes and revetments due to breaking waves. Results from field measurements are presented with respect to peak pressure values as well as to characteristics of pressure-time histories.

A Theoretical Model for Ship–Wave Impact Generated Sea Spray

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Shafiul Mintu ◽  
David Molyneux ◽  
Bruce Colbourne
Keyword(s):  
Theoretical Model ◽  
Field Measurements ◽  
Operating Conditions ◽  
Ship Motions ◽  
Wave Impact ◽  
Fishing Vessels ◽  
Semi Empirical ◽  
Wave Induced ◽  
Analytical Expressions ◽  
Ship Speed

Abstract Spray generated by ships traveling in cold oceans often leads to topside icing, which can be dangerous to vessels. Estimation of the spray flux is a first step in predicting icing accumulation. The amount of spray water, the duration of exposure to the spray, and the frequency at which the spray is generated are all important parameters in estimating the spray flux. Most existing spray flux formulae are based on field observations from small fishing vessels. They consider meteorological and oceanographic parameters but neglect the vessel behavior. Ship heave and pitch motions, together with ship speed, determine the frequency of spray events. Thus, the existing formulae are not generally applicable to different sizes and types of vessels. This paper develops simple methods to quantify spray properties in terms that can be applied to vessels of any size or type. Formulae to estimate water content and spray duration are derived based on principles of energy conservation and dimensional analysis. To estimate spray frequency considering ship motions, a theoretical model is proposed. The model inputs are restricted to ship’s principal particulars, operating conditions, and environmental conditions. Wave-induced motions are estimated using semi-empirical analytical expressions. A novel spray threshold is developed to separate deck wetness frequency from spray frequency. Spray flux estimates are validated against full-scale field measurements available in the open literature with reasonable agreement.

Ship-Wave Impact Generated Sea Spray: Part 2 — Formulating Spray Frequency

2020 ◽  
Author(s):  
Shafiul A. Mintu ◽  
David Molyneux ◽  
Bruce Colbourne
Keyword(s):  
Field Measurements ◽  
Operating Conditions ◽  
Sea Spray ◽  
Ship Motions ◽  
Empirical Formulas ◽  
Wave Impact ◽  
Quick Estimate ◽  
Semi Empirical ◽  
Wave Induced ◽  
Analytical Expressions

Abstract In certain, but not all, circumstances a cloud of spray forms after a wave impacts a ship. The frequency of spray events affects the icing process. Previous spray frequency formulas are derived empirically from field observations considering only the ship’s forward speed and oceanographic conditions. The significance of various degrees of ship motions on the spray frequency is ignored. However in reality, the interrelationships of heave and pitch motions under wave actions together with surge motion determine the number of spray events that a ship may experience in a given period of time. This paper introduces a theoretical model for estimating the frequency of sea spray considering ship motions. Ship motions can be easily estimated by strip/panel methods. However, in this work, the aim was to develop a simple framework for a quick estimate of spray frequency. The model inputs are, therefore, restricted to ship’s principal particulars, its operating conditions, and the environmental conditions. The wave-induced motions are estimated by semi empirical analytical expressions. A novel spray threshold is developed to keep the deck wetness frequency separated from the spray frequency. The proposed spray frequency formula is validated against available full-scale field measurements from a Russian fishing vessel, MFV Narva, and reasonable agreement is found. Limitations of previous empirical formulas are also discussed.

scholarly journals The thermal structure of the anoxic trough in Lake Untersee, Antarctica

2018 ◽  
Vol 30 (6) ◽  
pp. 333-344 ◽  
Author(s):  
James Bevington ◽  
Christopher P. McKay ◽  
Alfonso Davila ◽  
Ian Hawes ◽  
Yukiko Tanabe ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Solar Radiation ◽  
Water Temperature ◽  
Energy Input ◽  
Thermal Structure ◽  
Field Measurements ◽  
Maximum Depth ◽  
Antarctic Lake ◽  
Thermal Maximum ◽  
Anoxic Basin

AbstractLake Untersee is a perennially ice-covered Antarctic lake that consists of two basins. The deepest basin, next to the Anuchin Glacier is aerobic to its maximum depth of 160 m. The shallower basin has a maximum depth of 100 m, is anoxic below 80 m, and is shielded from convective currents. The thermal profile in the anoxic basin is unusual in that the water temperature below 50 m is constant at 4°C but rises to 5°C between 70 m and 80 m depth, then drops to 3.7°C at the bottom. Field measurements were used to conduct a thermal and stability analysis of the anoxic basin. The shape of the thermal maximum implies two discrete locations of energy input, one of 0.11 W m-2 at 71 m depth and one of 0.06 W m-2 at 80 m depth. Heat from microbial activity cannot account for the required amount of energy at either depth. Instead, absorption of solar radiation due to an increase in water opacity at these depths can account for the required energy input. Hence, while microbial metabolism is not an important source of heat, biomass increases opacity in the water column resulting in greater absorption of sunlight.

scholarly journals Study of Current- and Wave-Induced Sediment Transport in the Nowshahr Port Entrance Channel by Using Numerical Modeling and Field Measurements

2020 ◽  
Vol 8 (4) ◽  
pp. 284 ◽  
Author(s):  
Ayyuob Mahmoodi ◽  
Mir Ahmad Lashteh Neshaei ◽  
Abbas Mansouri ◽  
Mahmood Shafai Bejestan
Keyword(s):  
Numerical Modeling ◽  
Caspian Sea ◽  
Recirculation Zone ◽  
Numerical Models ◽  
Field Measurements ◽  
Sediment Sources ◽  
The Caspian Sea ◽  
Access Channel ◽  
Negative Impacts ◽  
Wave Induced

The Nowshahr port in the southern coastlines of the Caspian Sea is among the oldest northern ports of Iran, first commissioned in the year 1939. In recent years, this port has been faced with severe sedimentation issues in and around its entrance that has had negative impacts on the operability of the port. The present study aims at identifying major reasons for severe sedimentation in the port entrance. First, field measurements were evaluated to gain an in-depth view of the hydrodynamics of the study area. Numerical models then were calibrated and validated against existing field measurements. Results of numerical modeling indicated that wind-induced current is dominant in the Caspian Sea. The numerical results also indicated that in the case of an eastward current direction, the interaction between current and the western breakwater arm would lead to the formation of a separation zone and a recirculation zone to the east of the port entrance region. This eddying circulation could transport suspend settled sediments from eastern shoreline towards the port entrance and its access channel. The results of this paper are mostly based on the study of current patterns around the port in the storm conditions incorporate with the identification of sediment sources.

scholarly journals The Method for Evaluating Cross-Shore Migration of Sand Bar under the Influence of Nonlinear Waves Transformation

Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 214
Author(s):  
Margarita Shtremel ◽  
Yana Saprykina ◽  
Berna Ayat
Keyword(s):  
Sediment Transport ◽  
Nonlinear Wave ◽  
Maximum Amplitude ◽  
Field Measurements ◽  
Wave Transformation ◽  
Sandy Bottom ◽  
Divergence Point ◽  
Sand Bar ◽  
Wave Induced ◽  
Second Wave

Sand bar migration on the gently sloping sandy bottom in the coastal zone as a result of nonlinear wave transformation and corresponding sediment transport is discussed. Wave transformation on the intermediate depth causes periodic exchange of energy in space between the first and the second wave harmonics, accompanied by changes in the wave profile asymmetry. This leads to the occurrence of periodical fluctuations in the wave-induced sediment transport. It is shown that the position of the second nonlinear wave harmonic maximum determines location of the divergence point of sediment transport on the inclined bottom profile, where it changes direction from the onshore to the offshore. Such sediment transport pattern leads to formation of an underwater sand bar. A method is proposed to predict the position of the bar on an underwater slope after a storm based on calculation of the position of the maximum amplitude of the second nonlinear harmonic. The method is validated on the base of field measurements and ERA 5 reanalysis wave data.

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