输液质量管理规定

HSE Health & Safety Executive Guidelines for jack-up rigs with particular reference to foundation integrity Prepared by MSL Engineering Limited for the Health and Safety Executive 2004 RESEARCH REPORT 289 HSE Health & Safety Executive Guidelines for jack-up rigs with particular reference to foundation integrity Adrian Dier BSc., MSc., PhD., CEng, MICE, MASCE Brian Carroll BSc., MSc., PhD., CEng, MICE, MASCE Solmaz Abolfathi BSc., MSc. MSL Engineering Limited Platinum Blue House 18 The Avenue Egham Surrey TW20 9AB A jack-up rig is typically used at a dozen or more sites during its service life. It can therefore be expected to encounter a range of water depths, environmental load conditions and soil types. For each candidate site, an assessment is conducted to determine the suitability of the unit for the site and to provide data for the installation operation. Such assessments are normally conducted using the SNAME Technical and Research Bulletin 5-5A. This report addresses the foundations of jack-up rigs, with the overall objective of determining current knowledge and assessment practices. An exhaustive literature search was initially conducted to establish a database of knowledge. A review of the collated data identified case histories of foundation problems, and in turn the major challenges associated with foundation assessment. Various foundation topics (e.g. punch through, bearing and sliding capacity, existing footprints, rack phase difference, etc.) were then examined in depth and recommendations made. In many cases the recommendations are a reaffirmation of existing guidance; in other cases some improvements to the existing guidance are suggested. In the case of rack phase difference, there is no guidance in SNAME and therefore specific provisions have been developed herein. This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy. HSE BOOKS ii © Crown copyright 2004 First published 2004 ISBN 0 7176 2926 0 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording or otherwise) without the prior written permission of the copyright owner. Applications for reproduction should be made in writing to: Licensing Division, Her Majesty's Stationery Office, St Clements House, 2-16 Colegate, Norwich NR3 1BQ or by e-mail to hmsolicensing@cabinet-office.x.gsi.gov.uk iii CONTENTS Page No 1 EXECUTIVE SUMMARY.......................................................................................1 2 INTRODUCTION.....................................................................................................2 2.1 Background and Need for Study ..................................................................2 2.2 Scope of Work..............................................................................................2 3 AVAILABLE INFORMATION ...............................................................................4 3.1 Guidance Documents ...................................................................................4 3.2 Public Domain Literature .............................................................................5 3.3 Case Histories...............................................................................................7 4 ASSESSMENT OF INFORMATION ....................................................................15 4.1 Initial Penetration and Punch-Through ......................................................16 4.2 Bearing Failure and Settlement ..................................................................20 4.3 Sliding Failure ............................................................................................29 4.4 Previous Footprints ....................................................................................32 4.5 Significance of Rack Phase Difference (RPD)...........................................37 4.6 Scour…………….......................................................................................47 4.7 Layered Soils..............................................................................................52 4.8 Foundation Fixity .......................................................................................54 4.9 Jack-up Spudcan/Jacket Pile Interaction ....................................................57 4.10 Effects of Cyclic Loading...........................................................................59 4.11 Debris and Other Objects on Seabed..........................................................61 4.12 Shallow Gas Pockets ..................................................................................62 4.13 Seafloor Instability .....................................................................................63 4.14 Liquefaction ...............................................................................................65 iv 5 KEY FINDINGS AND CONCLUSIONS...............................................................70 5.1 Key Findings ..............................................................................................70 5.2 Conclusions ................................................................................................74 REFERENCES NOTATION 1 1 EXECUTIVE SUMMARY This document summarises a study undertaken by MSL Engineering Limited for the Health and Safety Executive. The study concerns the foundations of jack-up rigs, with the overall objective of determining current knowledge and assessment practices. In addition, some design guidelines on site specific integrity issues have been prepared. The work began with an exhaustive literature review; over 250 documents were sourced for the study. Case histories were collated from the sourced documents and over 50 incidents relating to jack-up foundation problems were identified. Punch-through (rapid penetration through a stronger soil layer overlying a weaker one) has the highest rate in foundation incident causes, accounting for over 50% of all foundation incidents and the great majority of fatalities that have occurred in jack-up foundation related accidents. The second highest rate in foundation incident causes is for uneven seabed / scour / footprints. The information contained in the literature, including existing guidance within SNAME and ISO documents, was assessed under various headings or topics: • punch-through • bearing failure and settlement • sliding failure • footprints • rack phase difference (RPD) • scour • layered soils • foundation fixity • jack-up spudcan and jacket pile interaction • cyclic loading • debris • shallow gas • seafloor instability • liquefaction. For each topic and as appropriate: definitions are given, the effects on foundation behaviour are described, analysis/assessment approaches are summarised, mitigation methods are presented, and recommendations are made. In many cases the recommendations are a reaffirmation of existing guidance; in other cases some improvements to the existing guidance are suggested. In the case of rack phase difference, there is no guidance in SNAME or ISO and therefore specific provisions for RPD have been developed. A number of flowcharts have been prepared. The flowcharts serve the following purposes: • A visual overview of potential problems that may be encountered during the jack-up installation phase • A visual overview of potential problems that may be encountered during in-service operations • A summary of the jack-up foundation design process • Detailed design process for selected topics. 2 2 INTRODUCTION This report has been prepared by MSL Engineering Limited (MSL) for the Health & Safety Executive (HSE) following various HSE/MSL discussions, and relates to the preparation of guidelines on the safety and integrity of jack-up rigs, with particular reference to foundation integrity. 2.1 BACKGROUND AND NEED FOR STUDY Over the past few years, a large number of research and technology development projects have been carried out in the UK and elsewhere on jack-up integrity. One of the primary focuses has been the integrity of jack-up foundation systems and associated risks. Whilst a significant amount of useful information has been generated, there is an increasing recognition that this information is diverse and not easily accessible by the practising engineer. A proposal was therefore prepared for HSE’s review and consideration, with the following target objectives: 1. To review/capture all information on the integrity of jack-up rigs, with specific focus on foundation and soil-structure interaction, including case histories. 2. To prepare a document on current knowledge and assessment practices. 3. To prepare engineering guidelines on site specific integrity issues. 2.2 SCOPE OF WORK The following scope of work was proposed to meet the above stated objectives: i. Capture all documents related to the integrity of jack-up rigs, including standards and recommended practices. ii. Undertake review of the present-day state-of-the-art and state-of-practice. iii. Identify and catalogue all relevant case histories. iv. Undertake a critical appraisal of all the foundation related matters, including the following: • Installation of jack-up rigs in close proximity to jacket structures, i.e. jack-up spudcan/jacket pile interaction • Initial penetration and punch-through • Settlement under storm loading/bearing failure • Foundation fixity • Sliding failure • Scour • Seafloor instability • Shallow gas pockets 3 • Existing debris • Sloping foundation and eccentric loading, and significance of Rack Phase Difference (RPD) • Previous footprints • Layered soils • Effects of cyclic loading • Liquefaction. v. Prepare guidelines with specific focus on foundation related matters. vi. Prepare report covering all work carried out and all findings. 4 3 AVAILABLE INFORMATION 3.1 GUIDANCE DOCUMENTS There are two principal sets of guidance documents covering design and assessment engineering of jack-ups, and these are discussed below. In this report, they are generally referred to as SNAME (1) and ISO (2) for simplicity. 3.1.1 SNAME The primary guidance used by the jack-up industry is “Society of Naval Architects and Marine Engineers Technical and Research Bulletin 5-5A”. The first edition of SNAME was issued in May 1994 and was based on a Joint Industry-Funded Project involving all sections of the industry. The background to the project was disseminated at a seminar (3) held at City University, London, in September 1993. There have been two revisions since the first edition. The first revision was issued in May 1997 and the second in January 2002. Unless noted otherwise, in this report a reference to SNAME implies the latest version (2002). The SNAME T&R Bulletin 5-5A 2002 contains four documents: • T&R5-5—“Guideline for Site Specific Assessment of Mobile Jack-Up Units” (First Edition – May 1994) • T&R5-5A—“Recommended Practice for Site Specific Assessment of Mobile Jack-Up Units” (First Edition – Rev 2, January 2002) • Commentaries to Recommended Practice for Site Specific Assessment of Mobile Jack-Up Units (First Edition – Rev 2, January 2002) • Example (“Go-By”) Calculation Using Recommended Practice For Site Specific Assessment of Mobile Jack-Up Units (Preliminary Issue – May 1994). The stated purpose of the guideline (T&R5-5) is to identify the factors that are likely to be the main concerns for any site assessment of a jack-up unit. It is not intended to be used as guidance for design or construction. The Recommended Practice document (T&R5-5A) provides specific provisions for use with the T&R5-5 Guideline. Each assessment should cover the areas of the Recommended Practice as appropriate for the particular jack-up and location. The Recommended Practice does not intend to impose calculation methods or procedures and leaves the engineer freedom to apply alternative practices within the framework of the accompanying Guideline. The Commentaries to the Recommended Practice provide background information, supporting documentation, and additional or alternative calculation methods as applicable. A summary of the coverage within SNAME for the topics investigated in this study is included in Table 1. 3.1.2 ISO The working draft ‘C’ of International Standard ISO, Part 1, entitled ‘Petroleum and Natural Gas Industries—Site specific assessment of mobile offshore units (ISO/WD 19905-1.4)’, was issued in October 2003 for review and comment. Part 2 of this document is the associated commentary. These documents are to be published as international standards in the future. They are very largely based on the SNAME documents, the main difference being purely one 5 of format. Unless noted otherwise, in this report a reference to ISO implies the working draft ‘C’, ISO/WD 19905-1.4 (2). There is also an ISO standard “ISO 19901-4:2003(E)” (4) on geotechnical and foundation design. However, this document does not cover all investigated topics in this study. A summary of ISO coverage for the topics investigated in this study is included in Table 1. Table 1 SNAME and ISO coverage of foundation issues No Topic Relevant Clause in SNAME Relevant Clause in ISO/ WD 19905-1.4 Level of Detail (SNAME) Level of Detail (ISO) 1 Punch-Through 6.2.6;8.3.5 A.9.3.2.7 Detailed Detailed (mainly follows SNAME) 2 Settlement under Storm Loading 6.3.3.4 A.9.3.3.2.4 Mentioned Mentioned 3 Sliding 6.3.3; 6.3.4; 8.3.1 13.7.2; A.9.3.3.2; A.9.3.3.3 Detailed Detailed (mainly follows SNAME) 4 Previous Footprints 6.4.2 9.3.4.2 Partly detailed Partly detailed (mainly follows SNAME) 5 Rack Phase Difference - - No mention No mention 6 Scour 6.4.3 9.3.4.3 Mentioned Mentioned 7 Layered Soils 6.2.6 A.9.3.2.7 Detailed Detailed (mainly follows SNAME) 8 Foundation Fixity 5.3; 6.3; 8.3 13.7.4; A.8.6.3; A.9.3.3.3; A.9.3.3.4 Detailed Detailed (mainly follows SNAME) 9 Spudcan/Pile Interaction 6.4.6 9.3.5; A.9.3.5 Mentioned Mentioned 10 Cyclic Loading 6.4.4 9.3.4.5 Mentioned Mentioned 11 Existing Debris 3.13.1 A.9.2.1.2 Mentioned Mentioned (mainly follows SNAME) 12 Shallow Gas Pockets 6.4.5 9.3.4.6 Mentioned Mentioned 13 Instability of Seafloor 6.4.4 9.3.4.4 Mentioned Mentioned 14 Liquefaction/Pore-pressure 6.4.4 9.3.4.5 Mentioned Mentioned As suggested by Table 1, ISO is very similar to SNAME since it is based on SNAME. However, ISO has more guidance than SNAME in some areas. 3.2 PUBLIC DOMAIN LITERATURE An extensive literature search was conducted to obtain comprehensive information regarding jack-up foundations. Data has been collected from the early years of jack-up use to the present-day. The following methods to identify and subsequently source documents were followed during this stage of the work: 6 (a) Internet Searches by keyword The World Wide Web was searched for information using keywords in Internet search engines. A number of keywords were used in the searches including: • Spud-can, spud can, spudcan • Jack-up, jackup, jack up • Footing • Fixity • Initial penetration • Debris • Scour • Footprint • Shallow gas, etc. (b) Internet searches of specific sites Also, a broad search has been done within specific websites that were thought likely to contain relevant information. These sites include: • Health and Safety Executive (HSE) website for OTO, OTH, OTI, RR reports, safety notices and more. • Minerals Management Service (MMS) website • International Association of Drilling Contractors (IADC) website • United Kingdom Offshore Operators Association (UKOOA) website • Centre of Offshore Foundations Systems (COFS) website, University of Western Australia. A large amount of relevant information and papers are available for downloading from this website. (c) MSL Engineering in-house library (d) Conference papers • Offshore Technology Conference (OTC), 1969-2003 • Jack-Up Platforms Conference, 1987-2003 • International Society of Offshore and Polar Engineers Conference (ISOPE), 1991- 2003 • Offshore Mechanics and Arctic Engineering Conference (OMAE), 1994-2003 • Behaviour of Offshore Structures conference (BOSS), 1976-2003 These conferences were checked for all years they have been held. (e) Journals and magazines Journals/magazines listed from citation and Internet searches were examined. The journals and magazines included: Oil and Gas Journal, Offshore Magazine, Journal of Offshore Mechanics and Arctic Engineering, Marine Structures, Japanese, Canadian and British Geotechnique magazines. Marine Structures and British Geotechnique journals were looked at with a greater effort as these appeared to have a greater proportion of relevant articles. 7 (f) Authors were contacted directly for further information on tracked papers and research. (g) Cited references Further documents were found from the reference lists of sourced papers and documents. Over 350 references were initially identified. Following a screening process, based mainly on document title, a total of 250 documents were thought to be of particular interest and were therefore sourced to form a “project library”. The documents in the project library were then reviewed, categorizing each document according to one or more of the various topic areas discussed in this report, and entered into a database. This stage of work is summarised in Table 2, which shows the breakdown by topic area and publication year. (Note, some documents cover more than one topic area.) Table 2 Classification of references by topic area and publication date Topic Area Before 1980 1981- 1990 1991- 2000 After 2001 Total Spudcan / Pile Interaction 0 8 8 7 23 Punch-Through 0 15 13 11 39 Settlement 1 4 14 10 29 Sliding 1 3 13 6 23 Scour 0 3 2 6 11 Instability of Seafloor 0 3 2 2 7 Shallow Gas 0 0 4 1 5 Debris 0 1 1 1 3 Rack Phase Difference 0 5 1 7 13 Footprints 0 3 2 10 15 Layered Soils 1 6 3 3 13 Cyclic Loading 0 7 20 8 35 Liquefaction / Pore-Pressure 1 1 9 2 13 Fixity 2 17 54 23 96 Fatigue 0 0 1 4 5 Risk of Impact with Jacket 0 0 4 4 8 Case History 0 10 13 10 33 Unclassified 3 2 13 9 27 Total No. of Documents 7 44 108 71 230 3.3 CASE HISTORIES During the collation and classification of obtained literature, those documents identifying case histories of failure incidents were tagged. Some of these incidents are discussed in detail in these references but the majority of them are just merely mentioned as having occurred. A table of the available data including jack-up name, location, date and cause of accident was prepared. Further investigation was carried out using the Internet to acquire more information (where available) about missing data for each case. It should be noted that in reality there might be many other incidents that have never been reported in the public domain. Therefore, the following set of data is not a complete database 8 and only reflects a limited experience. However, it is a complete collection of all available data on case histories in the project library. The data is compiled into Table 3. One third of jack-up accidents have been associated with foundation problems (5 & 6). Causes are classified to categories such as punch-through (during preloading or hurricane/storm events), uneven seabed / scour /