The amount of offshore pipeline construction work in Russia, in the Black, Baltic, Barents, Kara and Okhotsk. seas, will reach over 6,000 km, according to the predictions available. On Ag.1 - The Plan of transmission of pipelines through the Black Sea, on fig.2 - The structure of transmission of pipelines through the black Sea. Each of the above-mentioned projects has its own specific features. There are currently various options of the gas pipeline system construction from Russia to Turkey. One of the options is to lay the gas pipeline on the Black Sea bottom. The gas pipeline route crosses the Black Sea at depths reaching 2140 m. This option is characterized by the following specific features: large sea depth; complicated shore configuration, subject to seismic and landslide processes; a large amount of hydrogen sulfide (H2S) in water starting with a depth of 200 m and many others. The main problem of laying pipeline in deep sea water is to avoid pipe buckling due to bending under external pressure and its propaga-tion along the pipeline at great distances. The paper is focussed on the problems of determining the required wall thickness of the offshore pipeline. It provides some data related to the design of pipelines and their stability under combined external pressure and bending in accordance with the methods described in the draft Russian standard for design and construction of offshore pipeline systems. Gas Pipeline Design In designing offshore pipelines capability of transporting larger volumes of the product, it is usual practice to elevate the internal pressure to become comparable to external hydrostatic pressure. The hydraulic calculation on the basis of initial data (pipeline system output: 16 billion cu.m., the offshore pipeline length: 386 km, the input pressure: 25 MPa, the output pressure: 5.4 MPa) has shown that it would be desirable to construct either one line with an internal diameter of 700 mm, or two lines with an internal diameter of 534 mm.
For design of a slurred mineral waste retention pond which islocated near the sea-shore, west of Kaohusing fish harbor, Kaohusing city, Taiwan, its storage capacity is related to settling process of sediment which is known as quiescent consolidation which is highly influenced by buoyant force. The one-dimensional finite strain theory has been proved to be superior to conventional Terzaghi''s or Biots consolidation theories. However, comparison between analytical results of 1-D finite strain and field measurement by McVay et al. (1986) indicates that some discrepancies still exit. In this study, a two-dimensional plane strain extension of that consolidation theory is introduced. A governing equation of void ratio is derived and solved by a moving finite element method, in which the geometry is allowed to adjusted. For case study, succeeding theoretical results are verified against McVay''s field measurement and indicates more precise accuracy between them; thus, development of a 2-D plane strain assessment of quiescent consolidation processes is highlighted. INTRODUCTION The phosphate waste clay is the by-product of the benefaction process of the phosphate ore. This phosphate ore (termed "Matrix") occurs in a gravely, clayey sand and contains 113 phosphate, 113 granular materials (sand), and 113 clays. Merely the phosphate is needed as the primary source of phosphorous in inorganic fertilizers. The phosphate waste clay is pumped into large retention ponds and allowed to settle or consolidate (McVay, et aI., 1986). For designing the storage capacity and life cycle of the retention ponds, significant efforts had made to predict the rate of consolidation of the phosphate waste clay subjected to its self-weight and the final height of a retention pond. Proper description of the consolidation behavior would be one of the major abilities processed by the finite strain consolidation theory. It has been proved that the consolidation behavior of soft clays is more precisely descried by the finite strain consolidation theory
In this study, the problem of waves propagating over poro-elastic seabed is studied. The fluid motion is described by the linear wave theory. The poro-elastic seabed is modeled by the Biot theory, and the governing equations of the sixth-order differential equations for the displacements, and the fourth-order differential equation for the pressure are used. The seabed is currently considered infinite. Interfacial boundary conditions at the seabed surface are dynamic pressure and kinematic velocity continuity. In the solution procedure, the fluid motion and the seabed response are assumed to be periodic. General solution forms for the wave motion and the poro-elastic seabed can be derived. The coefficients in the solutions can be determined from the boundary conditions, and a dispersion equation for water waves is also obtained. The present analytic model can be simplified to the ones developed by Hsu and Jeng (1994), and by Tsai (1995). The present analytic solutions compare favorably well with experimental results by Yamamoto et al (1978) for both fine and coarse sands. Using the present analytic solution, effects of the porosity and stiffness of the elastic seabed on the wavelength are studied. Energy dissipation of propagating waves over poro-elastic seabed, and pressure variation along the water depth, can be estimated. INTRODUCTION The study of waves propagating over porous seabed has quite of its tradition. So far, it can be at least classified into two categories. One represented by Chen, Huang and Song (I997) using general equations for the coupled waves and poro-elastic seabed, and the other represented by Seymour, Jeng and Hsu (1996) using higher order differential equations for soil displacements and porous pressure. The two approaches have their benefits and disadvantages, and are therefore worthy of describing them.
All offshore platforms are designed with a specific design life in the Southeast Asia region, the design life is between 20 to 30 years. For operators in the Malaysian waters normally, the lease duration is between 20 to 25 years. The handover of these old platforms related to the superstructure (ageing equipment''s, vessels and other facilities), the Integrity of the substructure is the most Important factor in the safe operation of the platform. The RSR IS an indication of the platform''s integrity and depending on each operator, the minimum RSR value may vary Some operator might adopt a minimum RSR value of 2 0 while another might take a minimum value of 1.32. There is a growing need for reliable assessment method and in this paper a progressive collapse analysis is used to predict the existing platform''s actual capacity. No doubt that powerful computers are a prerequisite to perform this analysis. INTRODUCTION In the Malaysian territorial waters, offshore hydrocarbon producing platforms have been In existence Since the late 1960''s. These platforms were designed using codes and other requirements that was adequate In those days while most of them have updated "as- built" drawings, very few still have their original design documents intact. Although underwater Inspections were performed at specified intervals, not must more in terms of structural integrity is known. Therefore, a majority of operators are embarking on structural integrity assessment for their existing ageing offshore platform. The platforms that were found to be not in compliance with current established design codes and recommendations are considered for further analysis using advanced techniques. Determining a platform''s structural reserve strength ratio (RSR) is a method of assessing the structural Integrity of an existing offshore structure. This paper shall present the findings of testing model of a typical platform. The chosen platform No 1 is a 3-well tripod template jacket.