bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application Of Critical State Soil Mechanics To The Prediction Of Axial Capacity For Driven Piles In Clay
Authors: Kirby Robert C. , Wroth C. Peter 
Published: October 2008

ABSTRACT
A companion paper by Esrig et al {1977} describes the initial development of a general effective stress method for the prediction of axial capacity for driven piles in clay. A dominant physical characteristic of driven piles in clay is a zone of severely remolded soil around the pile. The available shear resistance of the soil in the remolded zone controls axial capacity for driven piles in clay. This paper summarizes how critical state soil mechanics was used during an initial study to describe the engineering properties and stress conditions of the soil in the remolded zone.
It is assumed that the reader is not familiar with the concepts of critical state soil mechanics. Those concepts relevant to the pile problem are briefly explained and procedures for estimating the necessary soil parameters by direct testing, or indirectly from correlations with index tests, are presented.
The changes in stress during pile driving and reconsolidation after pile driving are illustrated by stress paths.

INTRODUCTION
A companion paper by Esrig et al {1977} describes the initial development of a general effective stress method for the prediction of axial capacity for driven piles in clay. As noted in that paper, several distinct zones can be identified in the vicinity of a driven pile in clay. These zones are illustrated in Fig. 1. A zone of severe remolding due to pile driving encircles the pile as indicated by Zone A. The soil in this zone has experienced large displacements and has been "turned upside-down" by the pile driving operation. For displacement piles, the zone of severe remolding extends to at least 1.4 pile radii from the center of the pile based on volume considerations.
Outside the zone of severe remolding, the soil has been stressed by the increase in volume caused by pile installation. In this zone {Zone B}, the soil accommodates the pile installation by relatively small radial displacements. The soil in Zone B may become overstressed but it is not "turned upside-down" by the pile driving process. Soil displacements due to pile driving are influenced by the ground surface to some limited depth; below this depth, the soil displacements are in the radial direction only. Near the bottom of the pile the displacements are influenced by the pile tip.
An essential step in the development of a general effective stress method for prediction of axial capacity, of piles driven into clay, is the prediction of the effective stress in Zone A immediately after driving. This requires the use of a model for soil behavior which adequately describes the behavior of soils at large strains. The concepts of "critical state soil mechanics" {Schofield and Wroth, 1968} were developed to permit prediction of the behavior of soils at all strains but the cornerstone of this model is the state of stress at large strains.
Environmental Conditions on the Continental Shelf off West Greenland
Authors: Nielsen Hasle A. , Dietrich J.A. , Fabricius J.A. 
Published: October 2008

ABSTRACT
Petroleum exploration activities started on the Greenland Continental Shelf in 1975 and intensive data collection programs on hydrographic, metrological and ice conditions have been carried out during the summer and fall seasons 1975 and 1976.
The paper describes the environmental conditions in the Davis Strait with emphasis on the concession areas between latitudes 63°and 68°N
The wave climate which is strongly correlated with the storm conditions was found to vary with the location and the seasons with the most severe conditions occurring late fall. During 1975–76 the maximum recorded wave heights was 6,8 m with corresponding wave periods of Tz = 9,5 sec.
The currents on the shelf were found to be governed by a general northward circulation of water and tidal current. The tidal currents vary geographically from weak diurnal currents to strong semidiurnal currents. Variations in currents were also found with the depths. Maximum current velocities were in 1975–76 measured at 80 cm/sec and the daily net drift speed was typically 10–20 cm/sec.
The ice conditions are governed by the "Vestis" and icebergs of glacial origin. The app. one meter thick Vestis" moves southwards during the fall and covers large parts of the Davis Strait during winter and spring.
Icebergs are found in many sizes through out the year. They originate mainly from the east and south coasts and from the Disco Bay in the north. The maximum size and draught of the measured icebergs were 8.5 Mt and 50 m, respectively.

INTRODUCTION
Until offshore petroleum exploration began in 1975 only little attention had been paisa to the environmental conditions on the continental shelf in the Davis Strait off West Greenland
Only very limited hydrographic data was found to exist at the concession areas located up to 160 km off the coast between latitudes 63° and 68°N, and data on ice conditions which as the most critical factor for offshore operations in Ghese areas, was also found to be scarce.
In order to provide data on currents, icebergs, ice drift and weather conditions comprehensive environmental data collection programs were therefore carried out in 1975 and 1976 both by the Concessionaires (with Chevron Petroleum of Greenland as operator) and by the Ministry for Greenland. The Programs of the Concessionaires aimed primarily at providing sufficient data for planning and execution of drilling operations and was concentrated on the concession Ares while the programs of the Ministry also emphasized the effects of possible oil spills upon the sensitive arctic environment.
The Ministry's program in 1975 and 1976 was executed by the Danish Hydraulic Institute (DRI) and in 1976 DRI also performed the Industry's Weather ship program. Special iceberg profiling equipment was used in 1976 and a total number of 7 wave rider buoys and 35 Andrea recording current meters were deployed in water depths up to 600 m. The area involve in the 1975 and 1976 measuring programs are shown on Figs. 1-2.
The Neutrabaric Method For One-Atmosphere Working In Subsea Environments
Authors: Ball Kenneth 
Published: October 2008

ABSTRACT
This paper outlines a previously undisclosed and percents developed technique putting men into a working environment on the seabed. In essence it consists of encapsulating equipment to be accessed with one or more pressure vessels, leaving the vessels full of water but depressurizing them to a nominal one atmosphere absolute pressure. The NEUTRABARIC working entwinement so created is a safe, simple, easily controlled and easily purged environment requiring the minimum energy and support facilities for its pupation and maintenance. These factors mean that a submersible with its intently low carried envy capability can be used as a significant economic invention device. In the paper the basic Logia of the NEUTRABARIC method is developed and a typical application to a seabed washed completion is outlined.

INTRODUCTION
It is a characteristic of many of the most significant developments of our time that once one has passed through that phase of "seeing through the problem" -a saying common in educational capsizes on this side of the Atlantic mope so than in Europe or elsewhere - there is a tendency to self-examination on the parrot of the developers through questions such as "why didn't we see that before?" and to skepticism on the part of those with whom the development is shared by observations to the effect that "but that is obvious.? The more obvious it is after definition the more assured one can be that a fundamental step has been made.
So it has been with the NEUTRABARIC method for one atmosphere invention to subsea installation. In retrospect, one can say that the developers of the concept. Intertek Technical Slices Ltd., had lived on the edge of the solution for many years in connection with early developments of manned underwater vehicles and systems; solving specific problems related to certain preconceived overall project definitions; and watching such solutions become eve mope complex as routine development proceeded
No doubt out of frustration caused by the constant mergence of interlinked problems in development of underwater systems a measure of lateral thinking was applied to the situation, stated in its simplest terms, of man working underwater.
So it was that in early 1972, the concept of NEUTRABARIC ACCESS was born out of soon Latah investigation. Since 1972, a quiet but steady application and development of the NEUTRABARIC METHOD OF ACCESS has been proceeding. However, this present OTC is the first time that a formal publication of the concept has been made.
In this paper, it is proposed to build-up the problems, to which the NEUTRABARIC METHOD provides solutions, in a series of stages. The pattern to be followed bears a resemblance to man's history of seeking to work deep under water and it win then be more apparent that the significance of the NEUTRABARIC METHOD is the of basic principle as distinct from time-sequenced problem solving and development.
Concrete Offshore Structures - Behavior Of Full Scale Shells, Hydrostatically Loaded
Authors: Gausel E. , Hafskjold P.S. 
Published: October 2008

ABSTRACT
Findings from a pilot study of the strain development in the first Concept concrete platform, Mobil Beryl A, installed in the North Sea in 1975, were presented at OTC-75, Paper 2405, and OTC-76, Paper 2435.
The Cement and Concrete Research Institute The Norwegian Institute of Technology has continued and intensified these investigations on the third Concept platform, Stat fjord A, which is to be installed this summer(l977).
The objective of the research program is to study the strain development and the relationship between the strains and the external loads.
The conclusions drawn should also be valid for hydrostatically loaded shells in general and not only to this particular type of concrete platforms.

INTRODUCTION
It is a fact that the dimensions of the structural shell elements in the concrete platforms designed for The North Sea have a magnitude beyond our empirical knowledge. The structures are statically indeterminate to a very high degree.
Correspondingly the structural analysis is complex and tedious, especially concerning the construction period, and the question has been raised.
How reliable are these calculations and the resulting reinforcement?
The instrumentations done at Mobil Beryl A and Stat fjord A are steps to approach this problem by direct measurements on full scale structures
The construction methods used made it possible to study the response of clearly defined hydrostatic loads acting on the concrete structures during the construction stages, Fig. 1.

SCOPE OF THE STUDY
When the Cement and Concrete Research Institute started up the instrumentation in April 1974 on the Mobil Beryl A platform, previous instrumentation installed in offshore concrete structures had been confined to the foundation slab in order to monitor the contact pressure between the subsoil and the structure.
The following study mainly comprises the instrumentation started up in March 1975 on the Statfjord A platform.
This instrumentation is located higher up in the structure, and is aiming at the study of the structural behavior of the concrete proper.
The main objective in the research program on Mobil Beryl A as well as Statfjord A was to study the relationship between the measured strains and the external loads. This includes a study of the correlation between the response of the structure and the modulus of elasticity of the concrete determined from standard tests. The loading conditions are in this case unique since the external load is a pure hydrostatic pressure.
Fig. 2 and Fig. 3 indicate the hydrostatic loading during the stages of construction of Statfjord A.
Second End Flowline Connection Without Length Adjustment
Authors: Pras S. , Levallois E. , Gouraud O 
Published: October 2008

ABSTRACT
In order to reduce the cost of flowlines laying and connecting, by decreasing the duration of operations and the size of the supporting vessels, a new method of building the lines onshore, towing them to the site, and connecting both extremites without length adjustment on site has been set up and successfully tested in 50 meters of water depth in the Mediterranean sea, in May 1977.

INTRODUCTION
The french research association Deep Sea Production, formed by the three companies TOTAL - COMPAGNIE FRANCAISE DES PETROLES, INSTITUT FRANCAIS DU PETROLE and SOCIETE NATIONALE ELF-AQUITAINE, is studying the different subjects to be worked out to set up a complete scheme of development of an oil field by water depth beyond the reach of divers. One of these subjects is the flowlines installation.
Previous operations performed by ELF-AQUITAINE in Africa have shown that the cost of flowline laying could be considerably decreased by building the lines onshore, rigging them with pontoons and chains, launching and towing them to the site, instead of using lay-barges.
A flowline being designed to link two sub-marine structures, the last problem to be solved was the second end connection: because of the impossibility to build a line at the exact length necessary to reach the second structure, after having connected the other extremity of the line to the first one, the second end connection was performed by divers, who cut the over-length and installed cumbersome spool pieces. If these time-consuming operations are workable by shallow water, they become rapidly too costly and too hazardous by great depth.
The new way of connection that has been investigated consists of:building the line with a planned over lengthlaying the second end of the line in a well determined abandonment area,pulling this second end towards the subsea structure,locking the pulling head into the structuresettling the pulling head in the right position by hydraulic actuators,establishing the fluid connection by a connector like those used in drilling.
All the points 1 through 5 were experienced twice during the test, an accurate measurement of the position of the flowline hub taking the place of the fluid connection.

PURPOSES OF THE TEST
The opportunity of the test has been taken to get some information on other subjects related to the second end connection. Therefore this test had a threefold purpose :To perform the second-end connection by drag-inTo check that the trajectory of the pipe on the bottom during towing was consistent with the results obtained by model tests,To monitor the shape of the line by acoustic beacons during the above mentioned operations.

GENERAL DESCRIPTION OF THE TEST
In order to make easier the understanding of the results of the test, we shall first go through the main steps of it, and come back after to peculiar technical points.
Super Short Baseline Hydroacoustic Navigation System
Authors: Vestgaard Karstein , Hansen Kaare 
Published: October 2008

ABSTRACT
Underwater navigation with a super short baseline hydroacoustic navigation system is described.
The description contains design criterium and field experiences.
Offshore activities have a great need for transportable underwater navigation systems with a minimum time for set up and calibration.
Among such activities are tracking of submarines, divers, underwater towed pipes and structures, and as a position reference for dynamic positioned ships and semisubmersibles.
The paper deals with field experiences from operations mentioned above using a hydroacoustic navigation system based on the super short baseline (SSBL) prinsip for position reference.
The system has been used for tracking of pipeline during pull out from onshore base (STAVANGER TO STATFJORD A). Tracking of underwater plough for trenching and for navigating the pipeline into the trench (150 m depth). The system has been used for tracking submersibles during underwater inspection and survey operations. The system is installed onboard a diving support vessel and semi submersible where it is used as a stand alone position reference system.

INTRODUCTION
Hydroacoustic navigation systems are today used as a local positioning reference for ships and submersibles. The systems can also-provide a relative position reference between submersibles and surface ships.
The system can be used by itself as a stand alone navigation system, or it could be integrated with a surface navigation system to give absolute position.
The simplest obtainable hydroacoustic navigation system consists of display and control unit, a transducer unit on the ships hull and a transponder on the sea bed as shown in figure 1.
The system described in this paper is of this type. However, this system could be used in a more complex configuration.
The system is based on the super shortbase line (SSBL) prinsiple with all the acoustic transmit/receive elements housed in one single unit, providing a very simple compact installation. The SSBL system comprises the following main units figure 2.display and control unittransducer containing all the acoustic transmit/receive elementstransponders being the acoustic referende sourcevertical reference unit
The calculated position is based on range and direction measurements to one transponder giving the relative position between the transducer and the transponder. The system can measure relative position to five or more different transponders within the same area.
This is possible because each transponder has its own interrogation and reply frequency.
The system has been employed on project in the NORTH SEA during 1977, where it has been used on several tasks like:position reference for dynamic positioning on diving support vesseltracking operations (bottom tow of pipeline)positioning of a underwater trenching plowtracking of unmanned submersibles
Signature Measurements On The Water Gun Marine Seismig Source
Authors: French W.S. , Henson C.G. 
Published: October 2008

ABSTRACT
Source signature data for the water-gun marine seismic source were collected 45 miles south of Grand Isle, La., in water depths of 1,800 ft. Signatures were digitally recorded using calibrated near-field and far-field hydrophones for both a single water gun and a pair of interacting water guns. Single-gun tests were recorded for all combinations of the following two parameters: firing pressures of 2,400, 2,000, 1,800, and 1,000 psi; firing depths of 10, 20, 27, 40, and 80 ft. Gun interaction tests were conducted at 10-ft and 20-ft depths with a firing pressure of 2, 000 psi and gun separation of 4, 8, 12, and 20 ft. In addition, repeatability tests were conducted. The experimental procedures and test results are presented.

INTRODUCTION
The water-gun marine seismic source generates an acoustic signal by means of an implosive mechanism rather than an explosive mechanism. The following characteristics are claimed by the inventor of the water gun (SODERA-Societe pour le development de la Recherche Applique, Toulon, France). (1) The source is a purely implosive device and the bubble pulse effect characteristic of explosive sources is eliminated; (2) the output spectrum is expanded toward higher frequency relative to an air gun while maintaining an output power comparable to an air gun; and (3) the water gun can be interfaced with the same onboard equipment as used for air guns. The above claims quite naturally catch the attention of those of us interested in petroleum exploration by the seismic reflection method. As a result, Amoco, Geophysical Service, Inc. (GSI), and SODERA conducted a joint test to measure the signature characteristics of both a single water gun and pair of interacting water guns. Mica T water guns with 80-cu in. air consumption were used. The tests were conducted in July 1976 aboard a conventionally rigged seismic reflection vessel in about 1,800 ft of water in the Gulf of Mexico.
Fig. 1 shows the operation of the water gun. The water gun is constructed much like an air gun except that one of the chambers is filled with water prior to firing. Upon firing, compressed air accelerates a shuttle through the water-filled chamber, ejecting the water at high velocity through exit ports. The shuttle stops instantly upon reaching the exit ports, while the ejected water continues to move away creating a cavity. The cavity increases in size until the outward velocity of the ejected water is reduced to zero by hydrostatic pressure. Sea water then collapses implosively into the cavity creating the acoustic signal. With the water gun, no air is released into the water to produce subsequent bubble oscillations.
Pressure signatures radiated by the water guns were measured for different firing pressures and firing depths. The single-gun tests were recorded for all combinations of the following two parameters: firing pressures of 2,400, 2,000, 1,800, and 1,000 psi; firing depths of 10, 20, 27, 40, and 80 ft. Signatures from two interacting water guns also were Measured.
Model Tests On Continuous Line Bucket Mining System
Authors: Yamakado Norio , Handa Keiji , Usami Takeshi 
Published: October 2008

ABSTRACT
Authors have been studying the continuous line bucket (CLB) mining system, which is one of the mining methods to mine manganese nodules from deep sea floors, mainly through the model tests in an indoor test tank.
According to the results of the indoor tests, very small-scale field tests of the CLB mining system were carried out in depths of 50 to 8O m to pick up problems due to natural phenomena such as currents, winds, and waves and to understand an actual CLB mining system affected by these phenomena.
It is significant to circulate the loop line, which hangs many buckets, between the sea floor and the ship smoothly at the operation of the CLB mining system. The traction machine using umbrella-type wheels was adopted for these field tests.
As a result, satisfactorily smooth circulation of the loop line, which hung 75 buckets (about 1,500 cc in volume each), was obtained. It becomes clear that smooth circulation of loop line results in stable operation without the rope being tangled even when the ship alters her course. However, it may be entangled when the circulation is not smooth.
In order to avoid tangling the rope, some experiments on the method not to reduce the span between the descending and ascending lines were examined in these field tests. A continuous monitoring for behavioral patterns of buckets and rope line on the sea floor also was tried by using a pinger.

INTRODUCTION
Authors have been studying model tests of the continuous line bucket (CLB) mining system in order to have a deeper understanding of this system as one of the mining methods used for recovering manganese nodules found distributed over the deep sea floors. The model tests mostly were conducted in an indoor test tank. In such tests, however, there are limits to detection of the problem area resulting from alteration of natural phenomena such as currents, winds, and waves. For further development of the CLB mining system, it should be considered important that we find solutions for problems that surfaced on the basis of the experimental results obtained from field tests.
In this context, we conducted small-scale field tests on the applicability of the CLB mining system in Sagami Bay in water depths of 50 to 8O m.
In such field tests, the bucket behavior on the sea floor cannot be observed as in laboratory tests. It will have to be an indirect observation through the use of some measuring instruments. When a field test was conducted in 1975 at a site with 430 m of water depth, a Bucket Behavior Recorder, which was developed for this particular field test, was used to measure the dredging path of the bucket and the shape of the dredging line took on the sea floor. The data obtained by this Bucket Behavior Recorder were almost identical to those already obtained through laboratory tests.