bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effects Of Cyclic Loading On The Behavior Of Anisotropically Loaded Soft Clay
Authors: Arango Ignacio 
Published: October 2008

ABSTRACT
While clayey soils subjected to cyclic loading may show a decrease or an increase in undrained shear strength during and immediately after the stress applications, their moduli have been observed to decrease considerably. Cyclic loads produced by earthquake or storm wave action may, even at relatively low strain level cause considerable shear deformations in soft clays which are under initial shear stresses, as in sloping delta and bay deposits.
Laboratory test data are presented which show the effects of cyclic strain amplitude, rate and number of applications on the strength and modulus of clays. The use of the laboratory data to the solution of typical field problems is illustrated with an example.
Laboratory shake table tests on soft clay banks appear to validate the analysis procedure. Moreover, the results of the application of the method to the field case appear to be reasonable. It is concluded that this simplified method is a practical and reasonable way to obtain estimates of the dynamic deformation of sloping soft clay deposits.

INTRODUCTION
The expansion of industrial and commercial installations in highly populated near-water areas requires, in many cases, the use of land with poor subsurface conditions. This situation is illustrated in Figure 1, where fill is shown overlying a soft San Francisco Bay Mud deposit for subsequent use in a highway extension in the area.
Cyclic loading of the clay produced by water wave activity, or ground shaking induced by earthquakes in the region requires that the engineer search for appropriate answers to questions, such as:Is the site stable during and immediately after the cyclic loading?; or,What is the order of magnitude of the permanent deformations that the fill may sustain? Answers to both of these questions can be given at this time with a reasonable degree of confidence.
It is the purpose of this paper to review the experimental evidence that may be utilized to answer the first question, and to present a simplified method which provides an answer to the latter. The experimental validation of the method and its application to a practical case are also presented in the paper.

CLAY STRENGTH UNDER CYCLIC LOADING
Castro and Christian (1) have recently reviewed the findings of various investigators on this subject. The authors concluded that when a saturated undrained soil is subjected to cyclic loading followed by undrained compressive loading to failure, the static shear strength is equal to or very close to the static undrained shear strength for samples that failed without initial cyclic loading. For example, tests on San Francisco Bay Mud (2) indicated that for cyclic strains less than one half of the strain to failure in static tests, the loss of strength after cyclic loading was less than 10 per cent of the original peak strength.
Underwater Survey Using An Inertial Navigation System
Authors: Stankoff Alain , Tait R. A.R. 
Published: October 2008

ABSTRACT
Recent trials of an Inertial Navigation System onboard a manned submersible have proved that underwater distances over several hundred metres can be measured with an accuracy of about ±15 cm.
The system is completely self-contained, independent of transponders or beacons and free of underwater environment disturbances. It permits, in addition, to navigate over very long distances with accuracies comparable to those obtained with long or short base acoustic systems.
This means that a new tool is now available to the offshore industry to simplify and/or improve the efficiency and the accuracy of underwater jobs such as tie-ins, measurement of flow-line position and length, pipe-line surveys, installation of platforms, sea bottom profiling, Navigation in acoustically disturbed environment, etc?

INTRODUCTION
Inertial navigation systems have, in the past, found application in, particularly, fighter aircrafts and space vehicles. Such aircrafts required the system to be light enough, self contained and largely immune from external influences. Navigational data is presented on a plane perpendicularly to the local vertical and oriented with respect to the True North. The system basically measures the components of the acceleration along the reference axes and compute the position by integrating them twice. Due to various imperfections, the resulting integrals are drifting as a function of time, and, for aircraft systems, the order of magnitude of the drift is I Nm/hr which is unacceptable for underwater usage. To offer convenient navigation performances required the system to be completed by an additional information relative to the INS velocity drift. Unlike aircraft, submarines can easily stop during their survey, and stay motionless on the seabed. Then, during such a station, the inertial system is informed that the speed is null, can measure its own drift and takes it into account to correct the navigational data until another stop occurs, where the drift data will be updated. The accuracy of the correction depends on the residual motion of the system during the drift check and of the time interval between two stations. Preliminary laboratory results had shown that such an inertial system, corrected every minute, could give the position within a few centimeters, which was at least one order of magnitude better than conventional underwater positioning systems. Furthermore, in the underwater environment, being self contained and immune from external influences offered immediate advantages over transponder systems. As it was necessary to demonstrate the performances of such an accurate system over significant distances, but impossible to verify the absolute accuracy over pre-determined distances underwater, the present evaluation was performed in two steps :First, the absolute performances were accurately checked on a well-known circuit onshore, with the system mounted on a vehicle and driven at speeds simulating the submarine motion.
The Installation Of A Deep Water Dry Subsea Completion System
Authors: Stone William H. 
Published: October 2008

INTRODUCTION
The dry subsea completion described in this paper is not the first, but is the initial non-experimental "off the shelf" installation of a deep water one atmosphere air, shirt sleeve environment, dry habitat subsea completion.1–4 The following is a chronological account of this installation from the selection of the dry system to the commencement of actual oil production from the well. The selection of the total production system, the testing at a dry land test site, simulating underwater conditions of the complete system including the platform facilities and the TFL pump down system, the drilling and completion of the actual well, the installation of the wellhead cellar, the flowline connection, the underwater assembly and the start up of the actual production are included.
It is the author's intent that this paper will convey to operational engineering personnel a fundamental understanding of how this project was successfully accomplished. This paper is not a detailed technical treatise of the dry system for the scientific reader as what information is available elsewhere; However, if the reader wishes to delve into details of specific aspects of the system's various components, the many, vendors who contributed to this project are named to provide a means for the reader to obtain this information.

OBJECTIVES OF THE PROJECT
As exploratory drilling advanced into ever deeper waters, the need for sophisticated production systems to produce reserves in deep water became essential. However, the industry has very little experience in deep water production. Deep water is defined as below any depth divers can function effectively. Therefore, in 1974, Union Oil Company of California's management created the "Deep Water Subsea Completion Project" with the following goals:To complete and produce a well on the sea floor that world enable the company to gain experience and expertise in deep water production.To simulate, in an existing shallow water field, conditions below depths that divers can function effectively.To utilize functional hardware and methods whenever possible using "off the shelf", rather than experimental hardware or methods. Functional is defined as having been successfully used in the field.
The project's primary purpose was to gain deep water subsea production experience, not to begin a research and development program. The entire project was planned and implemented by the company's Gulf Coast Regional Operations personnel, not by a research or staff study group. The project was divided into the following phases:A study of- the "state of the art" of available systems.Selection and procurement of equipment.Dry land testing.Offshore installation.Well production.
A New Concept For Single Point Mooring Offshore Terminals
Authors: Di Tella V. , Di Campanile A. , Di Paruzzolo A. 
Published: October 2008

ABSTRACT
The paper describes a new type of offshore tanker terminal and the related specially developed method of analysis of its dynamic behaviour.
The system, called articulated leg mooring system "ARLEMS" is an improved single point moo r in g buoy capable of mooring large tankers and of with standing severe meteorological-oceanographic conditions.
It is essentially formed of an upper structure supporting the rotating table, connected to a basement standing on the sea bottom, by three tubular legs. Two cardan joints at the ends of each leg allow the upper structure to move horizontally.
The advantages of such a system, as well as those of the particular kinematics, are examined in detail. The important role played by cardan joints is pointed out.
Two basic configurations of the system, the "buoy ant body buoy" and the "buoyant legs buoy" and their basic applications are outlined.
The method of analysis of the dynamic behaviour of the buoy is based on the non-linear motion equations of the legs, taking into account the influence of the different forces and the particular kinematics of the system.
A computer program solving non-linear equations by a step-by-step integration technique has been developed; movements of the buoy, as well a s loads on the bow hawser, on the legs and on the joints, are evaluated for two typical water depths: 27,5 meters for the "buoyant body buoy" and 105 meters for the "buoyant legs buoy".

INTRODUCTION
The large amount of oil exchange all over the world has caused a great demand for oil terminals. Because of frequent lack of suitable natural harbours near oil fields, it has been necessary to provide off shore oil terminals; besides, these installations can be located far from port traffic, thus reducing pollution risks.
Various types of offshore oil terminals have been studied, experimented, realized; among the latter:fixed berth;tower mooring system;multiple buoy mooring (M. B. M.);single point mooring (S. P. M.). With the rapid increase of tanker size, the S. P. M. system has prevailed mainly because:fixed berths are very expensive;tower mooring system is expensive and rather exposed to collision hazards;M. B. M. system is not capable of mooring large tankers and requires much time for mooring operations. The catenary S. P. M. system is widely used today; its basic elements are:a cylindrical hull buoy anchored to the seabed by means of four, six or eight chain legs;a turntable, mounted on the buoy body, equipped with lights, valves, piping, floating hoses and bow hawser;a central swivel, mounted on the inner part of the buoy, to transfer the oil from fixed submarine hoses to rotating flow-lines. The growth, in recent years, of offshore oil production has called for oil terminals capable both of operating in great water depths and of withstanding severe meteorological-oceanographic conditions.
Marine Seismic Surveys
Authors: Espey H.R. 
Published: October 2008

ABSTRACT
The frontiers of petroleum exploration are principally in offshore areas where seismic surveys provide the only technical data for prospect evaluation. The marine seismic industry has grown from 15 crews at work in 1960 to 75 crews today. Worldwide expenditures on marine seismic surveys last year totaled $450 million. The average cost per mile of marine seismic data today is the same as it was 9 years ago. New technology has reduced operating costs counteracting inflation. Significant improvements have been made also in data quality and resolution.

MARINE SEISMIC SURVEYS
In offshore areas such as the Atlantic OCS and the Bering Sea, seismic surveys commonly provide the only source of technical data on which decisions can be made concerning lease acquisition. In such frontier areas few wells are available for use in conventional exploration techniques. Other methods used on land, such as surface geology, photo mapping, and satellite imagery, are not applicable in marine areas. Last year, the petroleum industry spent more than $450 million on marine seismic surveying, including the associated data processing and interpretation. This may seem like a large amount of money, but it is almost negligible compared with the additional outlay that is made based on the geophysical data. For example, the Atlantic offshore sale last year was preceded by 68 crew months of seismic work at a cost of $35 million. In that sale the petroleum industry bid $3.5 billion based principally on the seismic data.
Geophysics for many years has played a key role in petroleum exploration, but it is only in the past 15 years that its use in offshore areas has become significant. In terms of the number of seismic crews in the field, most of the activity is onshore (Fig. 1). Only 15 marine crews were at work in 1960, but this has increased to an average level of 75 in 1976. These figures are for the free world only. Essentially all of the work in 1960 was carried out in the Gulf of Mexico, while today marine crews are surveying the shelf areas off of every continent. Due to higher mobility, a marine crew typically records 10 times as much data as a land crew. For this reason, it is more useful to look at statistics in terms of line-miles of data recorded (Fig. 2).
In 1960, only 21 percent of the seismic data was recorded by marine crews. Last year, more than 800,000 line-miles of data were recorded offshore and this represented 67 percent of the total seismic activity. This reflects the increased dependence on offshore areas for new major discoveries. The increases in activity in 1973 and 1974 reflect the response to the energy crisis. The drop in activity in 1975 and 1976 is principally due to adverse government regulations and tax policies in the United States, Canada, and the Far East.
In 1971, the petroleum industry began placing an increased emphasis on finding new reserves in the United States.
A New Offshore Pile Aligning System
Authors: Boyadjieff George , House Horace , Roussel Herbert 
Published: October 2008

ABSTRACT
In offshore construction work related, to platforms, one of the difficult operations has been the connection of add-on sections to pin piles as they are driven into the sea floor. The reason for this difficulty has been the relative motion of the derrick barge and the fixed platform. This paper describes the design of and the application of a pile aligning system that makes this operation much easier to accomplish. It emphasizes the design of the system and its field operation conducted in the Gulf of Mexico. It describes the design concepts, the actual hardware used to implement these concepts, and the successful operation of this hardware on the actual job site.

INTRODUCTION
Steel platforms are conventionally pinned to the ocean floor with large diameter piling, either driven through the legs of the platform and/or through guides around the base of the platform. When platforms are set in appreciable water depth it is not feasible to handle the pipe in one section and it becomes necessary to add-on additional sections as the pile is advanced to the ocean floor and then driven into the ocean floor. The platform itself is grounded to the ocean floor, whereas the derrick associated with a derrick barge for handling the pile add-on sections is floating on the ocean surface. Consequently, there is relative motion between the section of piling to be added-on and the pile that has already been installed in the leg or guides around the platform itself. The amount of motion is, of course, a function of the wave action or sea state on the derrick barge. When the weather becomes a factor, it becomes a common practice to wait for calm seas even though the operation may be costing upwards of $50,000 per day to stand by.
Piling commonly used today is either 48" diameter or 54" diameter, with some piling over 90" in diameter. The accepted method of joining the add-on sections to the pile is by welding. Because this welding must be performed in the field, the connection time can approach three to twelve hours per connection, or longer depending on wall thickness. A time saving solution has been to use mechanical type connectors which theoretically eliminate the welding time and pay for themselves even though they may never be recovered. Experience to date, on the other hand, has proven that the motion described above makes it virtually impossible to align the connectors and successfully connect them. Sometimes the operation can take longer than welding would have in the first place; consequently, there has been a reluctance to use these connectors.
Finally, in the case of pile that is driven' through guides around the base of the platform (skirt piles), it is sometimes desirable to cut off the piles at the base of the platform and to remove the upper section of the pile since it is not needed to improve the stiffness of the jacket and thus considerable savings can result.
An Approach to the Maximum Storm
Authors: Goldman Joseph L. 
Published: October 2008

ABSTRACT
Four models of extreme storms were constructed that could retain their dynamic stability long enough to generate a fully developed sea. Two time-dependent distributions of wind, wave and swell are computed for each model for use in a realistic computation of directional wave spectra. The G-4 storm model in its stationary mode contains a maximum deep-water combined sea of over 200 ft. height with over 30 second-period.
While the 4 models, G-I ' through G-4', may not represent the ultimate conditions that can be realistically contemplated, they have been prepared to represent a step in the direction of determining the ultimate extreme conditions for a given location. These models represent storms that can occur within our present major climatic cycle based on global climatological and weather information of periods less than 200 years and on near continuous records of daily Northern Hemisphere pressure distributions of about 75 years.
Soaring costs due to limited resources, dictate greater care in attaining the proper design of offshore structures. When applied covertly these models can provide the environmental design criteria to help decrease the range between over-design and under-design.

INTRODUCTION
Prior to the advent of semi-permanent offshore operations that were fixed to a particular site, the hostility of the offshore environment was confined to accounts in ship's logs. A summary of these accounts by Bigelow and Edmondson (1947) indicated that extreme conditions in the Pacific were about twice as severe as in the Atlantic. The Pacific maxi= wave height was 112 ft., and the Atlantic maximum wave height was 60 ft. The famous Arakawa and Suda report (1953) of the 1935 typhoon that affected the 28 ships of the Japanese Fleet indicated 81 ft. significant waves. At the time of their report, all wave observations over 65 ft. were discounted. A later comparison of the 1935 typhoon with Hurricane Carla by Freeman and Davis (1972) indicates that the high waves may indeed have been accurate observations.
Historical accounts of high waves encountered by ships in the Atlantic indicate an increase with time. In January, 1894, a ship off the west coast of Scotland reported many 30 ft. (significant) waves during a storm with some reaching 43 ft. (maximum). In February, 1900, in a storm off the northwest coast of Scotland, waves of 35 ft. were reported offshore from Peterhead. During February, 1907, an ocean liner 400 miles southwest of Iceland encountered a 'huge swell with waves up to 41 ft. (maximum). During December, 1911, a ship encountered up to 40 ft. waves (maximum) indicating a storm in the Bay of Biscay. Calculations of wave heights, from data supplied by ships officers, indicated a wave of 60 ft. (maximum) encountered southwest of Iceland during February, 1923. Photographic evidence of multiple waves over 36 ft. (significant) were obtained from a ship south of Newfoundland during March, 1929. These storm events have been confirmed by Freeman and Davis (1972) with weather maps.
Bottom Stability as a Factor in Platform Siting and Design
Authors: Garrison L.E. , Bea R.G. 
Published: October 2008

ABSTRACT
The stability of bottom sediments is a critical factor in the emplacement of offshore platforms. It should first be investigated early in the pre-sitting stage when reconnaissance surveys might reveal areas to be avoided or conditions that must be accommodated. More detailed studies of specific sites should follow to characterize local soil properties. In the design process, sea floor soils and the foundation elements of the platform should be considered as two components of a single system that together comprise the platform substructure. The strength and load-deformation characteristics of the soils, just as any other element of the platform system, must be determined for the projected lifetime of the facility.
Principal sea floor instabilities are downslope mass movements of sediments, sediment moved about by various transporting agents, and faulting. These can be recognized and characterized by a five-part program of interdisciplinary study consisting of geology, geophysics, environmental mechanics, soil reconnaissance, and the development of analytical models.
To provide the basic research for understanding these problems, acquire adequate information on bottom stability in frontier areas, and build and maintain a data base for input to analytical models, a cooperative effort between industry and government will be necessary.

INTRODUCTION
Experience in Outer Continental Shelf (OCS) areas has shown that in many cases a primary factor in platform sitting and design is the potential instability or the bottom sediments. Moreover, available information on sea floor conditions in frontier OCS areas indicates that similar concerns exist there. These problems are, for the most part, being successfully resolved with available technology, but at a considerable cost in overdesign and redundant measures. Although rapid progress is being made toward understanding the nature of bottom instability and improving the means of quantifying it, much remains to be learned. Meanwhile, the economy and safety of platform design can be improved simply by the early identification of sea floor stability problems, and by the careful assessment of expected soil performance.
The following discussion will briefly review the problems of bottom instability as they affect platform sitting and design, the techniques for recognizing and analyzing soil performance, and a possible approach by government and industry toward gathering the information necessary to resolve these problems.

THE PLATFORM SYSTEM
An offshore platform consists of two major components. They are:The substructure, which consists of the soils in the vicinity of the platform and the foundation elements and well-conductors that receive their support from these soils, andthe superstructure, which consists of the braces, legs, and other steel and concrete elements that bridge the distance from sea floor to deck level, as well as the deck girders and beams that support the drilling and production equipment.