bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ice/Berm Interactions
Authors: Dunwoody A.B. , Losch J.A. , Been K.B. 
Published: October 2008

ABSTRACT
A physical model study was undertaken to develop a better understanding of ice-berm interactions. After reviewing the important considerations in the problem, a simple apparatus was constructed to model the main physical phenomena involved. Thirty-four tests were run over a range of floe face geometries and vertical stiffnesses of the leading edge of the floe. The main conclusions from the model tests were that the horizontal load is proportional to the stiffness for low values of stiffness and that the floe face geometry has minimal influence on the loads.

INTRODUCTI ON
One of the primary considerations in the design of an exploration or production facility in the arctic environment is the loading condition by thick ice features. Most artificial islands incorporate sand or gravel slopes as either a conventional fill island or as a berm that supports a caisson. The larger ice features will initially contact this sand slope and the ensuing ride-up and/or dig-in of the floe results in a dissipation of some or all of its kinetic energy. However, there exists little of either small-scale or full-scale data on ice-berm interactions. Therefore, predictions of ice-berm interactions must be based on untested numerical models.
This paper details a physical model study, the objective of which was a better understanding of ice-berm interactions. A simple apparatus was constructed to model the main physical phenomena involved. Force and deflection data were recorded for a number of simulated interactions. Two of the parameters of the ice floe were varied between interactions. Qualitative observations were a1so made during the interact ions. The results of the test program were applied to a full-scale problem through the appropriate scaling laws.
The physical model test program was carried out during the summer of 1983 under the auspices of APOA study #205.

TEST DESIGN
Before describing the test procedure or results, it is necessary to describe the rational that went into the design of the test program. An idealized ice-berm interaction was desired so that the main physical phenomena involved could be studied without distractions from secondary effects. To understand what the main physical phenomena are, consider what would happen during an interaction between ice floe and a herm. As the floe makes initial contact with the berm, the floe would begin to displace some of the soil. The soil would apply some horizontal, and possibly some vertical, reaction to the floe. The vertical component of the reaction would cause the leading edge of the floe to be deflected upward. As the floe continued to advance, greater horizontal and vertical reactions would be generated. The leading edge of the floe would be deflected upward further. After sufficient uplift, the ice floe would crack at some distance behind the leading edge.
Self-Bored Pressuremeter Testing in the Arctic Offshore
Authors: Hughes J.M.O. , Jefferies M.G. , Morris D.L. 
Published: October 2008

ABSTRACT
Self-bored pressuremeter (SBP) tests are an important part of site investigations for gravity base structure (GBS) foundations. This applies in particular when such structures are expected to experience significant lateral loads, as most arctic structures are. The SBP data is used for both serviceability state analysis and for providing fundamental information on undisturbed soil behavior.
SBP testing has been carried out offshore for Gulf Canada Resources Inc. (GCRI) during the past two years (1982-1983 arctic open water seasons). Testing has been carried out in a variety of soil conditions across the GCRI land interest on the Canadian continental shelf in the Beaufort Sea. The paper outlines the equipment used, operational successes and difficulties, and presents productivity data. Techniques and equipment for improving productivity are outlined. Experience with SBP operations has shown that the SBP is no more difficult to use offshore than the electric static cone penetrometer (CPT).
One result in particular of the SBP testing stands out; the in-situ geostatic stress ratio (Ko) has been found to be not a unique function of past overburden hi story. This result is discussed in the geological context. It appears prudent to regard as an independent variable for engineering purposes.

INTRODUCTION
An estimated 12 percent of the worlds untapped hydrocarbon reserves occur with in the Canadian Offshore regions (Beaufort Sea, Labrador Coast, Scotian Shelf and Arctic Islands). Gulf Canada Resources Inc. (GCRI) has significant interest in all these areas and is a major operator in the Beaufort Sea.
The Beaufort Sea is characterized by being frozen and ice covered for about 9 months each year. This ice cover presents the principal environmental constraint in offshore operations because of the large forces it may exert on stationary structures [1].
Artifical islands have proved successful in resisting large, horizontal ice forces in shallow waters. However, the average water depth of the GCRI land interest is about 35 m (115 ft). Artifical islands would be very expensive in such water depths so caisson technology has been developed as a technique for gaining the performance of islands without their cost. The GCRI system is called the Mobile Arctic Caisson (MAC). The MAC is a hybrid soil-steel structure and the principles of its design and operation have been presented elsewhere [2], [3]. A prerequisite to deployment of the MAC is a site investigation paying particularly attention to the foundation response under inclined and dynamic load vectors.
GCRI has carried out site investigations at various sites within its land interest during 1981, 1982 and 1983. However, it was found during 1981 that conventional laboratory tests gave scattered and ambiguous results at some sites.
Cyclic Pressuremeter Tests for Cyclic Lateral Loads
Authors: Briaud J.L. , Riner K.B. , Ohya S. 
Published: October 2008

ABSTRACT
The results of thirteen cyclic pressuremeter tests performed in hand augured holes on a stiff clay are presented. These tests show that the slope of the unload-reload loop stabilizes after only a few cycles but that the strain at the peak of the cycle continues to cumulate long after the slope of the loop has stabilized. It is also shown that the ratio of the peak pressure of the cycle to the net limit pressure is a major factor influencing the rate at which the cyclic strain cumulates with increasing number of cycles, while the ratio of the pressure range of the cycle to the net limit pressure is only a minor factor. Finally, recommendations are made to obtain the degraded cyclic pressure meter curves from the static pressure meter curve, and potential applications are discussed.

INTRODUCTION
In situ testing is becoming more and more useful in offshore geotechnical engineering (4). The remote vane was the first in situ tool to be used in the early 1970's, then the cone penetrometer followed, and more recently the pressuremeter has emerged as the third generation of in situ testing devices. Already two pressuremeters have been developed and used offshore. They are the PIP from Stress probe (16) and the PAM from the French Petroleum Institute (11). Others are-in the phase of development by companies such as Fugro and OYO.
The pressuremeter has advantages and drawbacks. Used in the proper situations, the pressuremeter can be extremely useful and save money. One of the most obvious applications of the pressuremeter test is the design of laterally loaded piles. Several methods have been developed (6). The purpose of this research was to study in details the soil response to cyclic pressuremeter testing; this represents the first step in the extension of an existing pressuremeter method for piles subjected to static lateral loads (7,8,10) to one for piles subjected to cyclic lateral loads.

SOIL CONDITION
The site was the Texas A&M University Research Annex. The soil at the site is a stiff clay with the following soil characteristics: liquid limit 50%, plastic limit 20%, natural water content 25%, total unit weight 128 lb/ft3 The undrained shear strength from unconfined compression tests varies from 1000 to 4000 lb/ft2 and averages 2000 lb/ft2. The water table is approximately 15 ft deep.
The average pressure meter limit pressure was 5 tsf and the average pressure meter modulus 100 tsf for a modulus over limit pressure ratio of 20 indicative of an over consolidated clay.

PRESSUREMETERS USED AND BOREHOLE PREPARATION
Two pressure meters were used at the site: The OYO Elastmeter 100 and the TEXAM Pressure meter. The OYO Elastmeter 100 (14) is a gas inflated mono cell Pressure meter which is used in a prebored hole.
Ambient Pressure Sampler System for Deep Ocean Soil Investigations
Authors: Zuidberg H.M. , Schrier W.H. , Pieters W.H. 
Published: October 2008

ABSTRACT
In the course of the preparation for a major offshore soil investigation in potentially gas-charged clayey sediments in the Norwegian Trench in the North Sea, a special sampler was built. The tool can retrieve soil samples under ambient (downhole) pressure to allow a quantitative assessment of the amount of gas in the sediment. This "Ambient Pressure Sampler" forms part of the routinely available soil testing package and allows the quick retrieval of a 65 cm3 pressurized sample. The sampler consists of a ball-valve placed at the lower end of a remote-controlled hydraulic push-sampling device. The tool can be operated on a routine basis in the course of a standard soil investigation program. This paper describes the design parameters of the tool and the actual design and the working procedures. Operational experience offshore is discussed as well as the general test results.

INTRODUCTION
In 1983 A/S Norske Shell awarded Fugro B.V. a soil investigation program in the Troll field offshore Norway. The site is located in the Norwegian Trench, which has a water depth of about 330 meters. The soil stratigraphy consists of 60 meters of normally or slightly over consolidated clays overlying hard clays, sand, and gravels.
The general area is covered with pockmarks and geophysical records showed typical anomalies. Both of these facts led the client to believe that shallow gas could be present, which may have migrated through the soft top layers. They requested a study to determine whether it would be possible to sample the soft clay in such a way that gas, potentially entrapped in the clay, could be preserved during retrieval and storage of the samples. The total soil investigation program and its objectives have been described. In this paper, the specific problem of gaseous soil sampling and its solution in terms of hardware and procedures is discussed. The sampler that was newly designed and constructed has been named the Ambient Pressure Sampler (APS).

THE PROBLEM OF GASEOUS SOILS
If gas molecules or free gas is present in the soil, it has either been generated locally by the decomposition of embedded organic matter or it has migrated from a petrogenic reservoir. Soil engineers, geologists, and geochemists are interested to know about the origin, nature, and quantity of the gas for various reasons: The local generation or migration of gas, if present in enough quantity, can pose a hazard to a platform.
Gas present in the soil can affect the soil behavior and results of a soil investigation.
Normal soil samples are subject to decompression during retrieval to the surface. Vaporization of the gas molecules in the pore water and expansion of the gas during decompression will disturb the soil samples, thus affecting the quality of subsequent laboratory tests.
The Distribution of Ice Pressure on Offshore Pile Structure and the Failure Mechanics of Ice Sheet
Authors: Saeki H. , Tanaka S. , Ono T. 
Published: October 2008

ABSTRACT
The total ice force acting on offshore pile structures, located in cold regions, has already been investigated by many researchers. However, few papers have described the distribution of ice pressure on the structures and the failure mechanics of ice sheet. It is necessary to study them in order to design the pile structures, keeping in mind safety and economic factors. The results of our experiments on failure mechanics of an ice sheet are useful for dynamic analysis. For analysis of stress and, especially, local buckling of structures, it is essential to examine the distribution of ice pressure acting on the structures.
This paper describes a systematic study of these aspects through field tests with three rectangular piles (20, 40, 60 cm in width) in Saroma Lagoon to clarify the effect of aspect ratio. It is clear from our experiments on ice pressure that the distribution of ice pressure can be classified into two types according to the strain rate ë (= v/4B, v: penetration velocity of piles B: pile width) defined by Michel and Toussaint in each aspect ratio, B/h (h: ice thickness). It is our hypothesis that the failure periods of ice sheet are determined by the strain rate and the aspect ratio mentioned above.

INTRODUCTION
In order for exploration and production in the oil begins of the offshore Arctic to be possible, it will be necessary to build structures capable of withstanding forces caused by the movement of the surrounding ice sheet. It is important to explain the interaction between the structures and the ice sheet so that they may be designed more rationally.
Total ice force acting on the structures has previously been discussed, mainly in regard to the interaction. However, they can't be properly designed only on the basis of the total ice force. Stress analysis of local buckling on structures, especially those having a large diameter and thin wall, should be carried out. The equation for the total ice force acting on the structures, arrived at by the authors, can be expressed as follows:(Mathematical equation available in full paper)
If local buckling occurs at the area of contact with the ice sheet, the value of the above shape factor, namely C, will increase and the total ice force is considered to become larger. The distribution of ice pressure must be obtained in order to examine whether or not local buckling occurs on the wall of the structures.
Moreover, the structures are severely damaged by the interactive interference between them and ice sheet. In fact, the marine lighthouse in the Bosnia Sea has received such damage. Dynamic analysis through numerical simulation should be carried out in order to prevent structures from receiving this damage. Maattanen, and Matlock et al. have studied the above problem, however, few papers have been issued, which describe the dynamic analysis from the perspective of failure periods and failure modes of ice sheet.
Shear Strength of Adfreeze Bond and Its Effect on Global Ice Load Applied to Mobile Offshore Drilling Units Under Arctic Conditions
Authors: Gershunov E.M. 
Published: October 2008

ABSTRACT
Theoretical results of calculating the global ice load which can be imposed on a conical and/or cylindrical type offshore structure as a result of the shear failure of the ad freeze bond are discussed. It is shown that the ice load required to fail the adfreeze bond essentially depends upon the shear strength of the adfreeze bond and the cone angle of the structure. If the adfreeze bond is strong enough, the ice load required to fail it in shear can be greater than the load imposed on the structure due to ice which fails in bending. In other words, under certain circumstances, the global ice load caused by the shear failure of the adfreeze bond, rather than the load due to the bending failure of ice, can govern the design. Experimental results confirm that conclusion.

INTRODUCTION
A major feature of a sloping sided structure is that it provides the possibility for the ice to ride up on the structure and fail in bending rather than in compressive crushing. Due to the fact that the ice fails in bending, the global ice load imposed on the structure is substantially less than the load which would be imposed on the same structure if it did not have a sloping side. Generally, this is true if one makes the simple assumption that the adfreeze bond between the structure and ambient ice field does not exist or is very weak. However, if the ice forms a strong adfreeze bond around the structure, the bending failure of the ice can occur only after this adfreeze bond fails. The primary objective of this paper is to show that under certain circumstances the structure can be exposed to a substantially larger global ice load due to adfreeze than it would be simply due to the load associated with a bending failure of the ice.
This phenomenon is the direct consequence of a strong adfreeze bond which can .be formed at the structure-ice interface.

STRENGTH OF ADFREEZE BOND
Reference 1 is an extensive literature search in which over 20 sources of experimental information were reviewed. The results of that study (Reference 1) show that the strength of the adfreeze bond depends upon numerous conditions including such things as salt concentration in water, temperature differential between air, water, ice and structural wall which is subjected to the ice, surface characteristics, freezing rate and crystal formation in ice, method used to apply protective coatings and the types 'of coating used. Since there is no reliable means of calculating the strength of the adfreeze bond, the designer must obtain data from model or actual field tests. However, at the present time, there is a lack of uniformity in the test conditions and procedures which have been used.
Analysis and Design of an Ice Wall Framing System for an Arctic Drilling Structure
Authors: Schlechten J.R. , Fernandes R.L. , Dolan D.K. , Bivens H.R. 
Published: October 2008

ABSTRACT
The exterior shell of a concrete base structure for an arctic oil drilling platform must be designed to resist extremely high local ice pressures. Stringent draft criteria for deployment of these structures in shallow waters require that the exterior shells, commonly called ice walls, have minimal weight in conjunction with maximum strength.
These conflicting requirements are satisfactorily balanced by the selection of an arch shape on the interior face of the wall. This geometry induces arching action within the ice wall plate to resist ice loads in compression, thereby minimizing principal tension within the concrete. The development of principal tension in a concrete structure limits its ability to resist external forces. This paper describes the design of a pre-stressed concrete ice wall which satisfies these load, weight, and material constraints.

INTRODUCTION
An exploratory oil drilling rig for use in Harrison Bay of the Beaufort Sea of Alaska is being designed for SOHIO Construction Company. This facility is intended for use in the ice-infested waters of Harrison Bay in water depths ranging from 40 to 60 ft.
The SOHIO Arctic Mobile Structure (SAMS) consists of a 345-ft octagonally shaped concrete base structure. (See Figure 1.) The height of the base structure varies from 50 ft in the central bays (under the drilling facility) to 70 ft in the exterior bay. A steel perimeter superstructure extends the exterior bay of the structure to a total height of 112 ft above the bottom of the concrete base. The drilling facility for SAMS is located in the 257-ft octagonally shaped area enclosed within the perimeter superstructure and above the concrete base structure. Spuds (shear piles) 7 ft in diameter are to be driven into the underlying soils to prevent SAMS from sliding due to a combination of high ice forces and weak soils.
The global ice forces and local ice pressures were the primary loads that controlled the design of the concrete base structure. Design of the structure's exterior shell (or ice wall) is controlled by the extremely high local ice pressures that develop as an ice feature is crushed against it.
The exterior shell of the base structure is the primary ice-resisting element and constitutes approximately 20% of the base structure weight. Thus, considerable effort was expended to minimize its weight to meet stringent draft criteria, including the use of light weight concrete. The fully saturated, reinforced concrete is expected to have an average in-place unit weight of 133 pcf. The design strength of the lightweight concrete is for 7000 psi (measured at 90 days).
An arch shape on the interior face of the ice wall was selected to induce an arching action within the ice wall. The arching action resists ice loads by compression, thereby minimizing principal tension.
Predicting Offshore Soil Conditions
Authors: Campbell K.J. 
Published: October 2008

ABSTRACT
This paper describes a practical method for developing predictive soil models for large offshore areas. The models are developed by synthesizing geologic background information, high-resolution seismic reflection data, and soil boring results. The geologic information provides reasonable limits for the predicted range in soil conditions. Seismic data define the three-dimensional relationships among soil units and provide a framework for relating soil borings to one another. The soil borings 'calibrate' the model by defining soil stratigraphy and geotechnical properties at key locations. Components of a soil model are: a soil province map showing areas where soil conditions are similar; soil cross sections to show the vertical relationships among soil units; and a representative soil profile for each soil province. Soil models can be used to predict general soil conditions throughout a study area, but not exact soil conditions at specific sites. Reliability of predictive models varies according to geologic complexity; the amount, type, and quality of data used; and the experience of those who develop the model. The method described has been used successfully to develop models for several Alaskan OCS areas and other frontier areas.

INTRODUCTION
The purpose of this paper is to describe a practical method for predicting general soil conditions offshore, and to discuss the limitations and factors affecting the reliability of this method. The method is most applicable for predicting soil conditions of large frontier areas tens of miles on a side, but ranging downwards to areas about the size of an individual lease block. Knowledge of general soil conditions is needed for conceptual and preliminary design of foundations, for various pre-lease economic analyses, for feasibility studies, for preliminary drilling and construction planning, and for planning geotechnical site investigations. Predicting soils at individual sites is not specifically addressed here, but aspects of the general method and its limitations as described here would also apply to site investigations.
The method consists of first developing a geologic model and then transforming the geologic model into a predictive soil model. The models are developed by synthesizing geologic background information, high-resolution seismic reflection data, and soil boring data. The method involves considerable interpretation and judgment, but is the most rational method readily available today for predicting general soil conditions for large areas.
Geophysical techniques are being developed that will complement the seismic data now used. These techniques are anticipated to provide direct identification of materials and to significantly increase the reliability of regional soil models. However, none of these techniques are expected to be perfected for geotechnical applications and be routinely available on an operational basis for at least several years and probably much longer.

GENERAL APPROACH
The method described here involves three basic steps;