ASUC Underpinning and Mini Piling Guidelines
Total Page：16
File Type：pdf, Size：1020Kb
ASUC | Guidelines on Safe and ecient UNDERPINNING AND MINI PILING OPERATIONS 3rd Edition ASUC Underpinning & Subsidence Repair Techniques | Engineered Foundation Solutions | Retro Fit Basement Construction Kingsley House, Ganders Business Park , Kingsley, Bordon, Hampshire GU35 9LU Tel: +44 (0)1420 471613 www.asuc.org.uk ASUC ASUC is an independent trade association formed by a number of leading contractors to promote professional and technical competence within the underpinning industry. Members offer a comprehensive range of specialist domestic services in: underpinning and subsidence repair techniques, engineered foundation solutions and retrofit basement construction. Any contractor wishing to join ASUC must first undergo a technical, health & safety, insurance and financial audit and make a commitment to prescribed safety procedures. It publishes a number of useful documents on underpinning and related activities and a comprehensive directory of members all of which are freely available to download via the website. ASUC members offer 10 or 12 year, depending on the nature of the works, insurance backed latent defects guarantees. Main authors Rob Withers - ASUC Executive Director David Kitching – Stress UK Ltd Lewis O’Connor – Abbey Pynford Group Industry comments from Hurst Pierce and Malcolm Abbey Pynford Group Morcon Foundations Photographs and Diagrams Abbey Pynford Group Falcon Structural Repairs Ltd Force Foundations Ltd t/a Basement Force Kixx Ltd – Mike Darby Larsen Foundations Ltd Neil Foundations Ltd Patterson Construction Ltd MJ Rooney Construction U&M Group Although care has been taken to ensure, to the best of our knowledge, that all data and information contained in this document is accurate to the extent that it relates to either matters of fact or accepted practice or matters of opinion at the time of publication, neither ASUCplus, the authors or contributors nor the co-publishers will be liable for any technical, editorial, typographical or other errors or omissions in or misinterpretations of the data and information provided in this document. Since this document may be subject to change and updating, the data and information which it contains is only correct at the time of publication. Compliance with this document does not of itself infer immunity. Part-funded by This project has been delivered with support from the CITB Growth Fund, which aims to ensure that the construction industry has the right people, with the right skills, in the right place, at the right time and is equipped to meet the future skills demands of the industry Guidelines on safe and efficient Underpinning and Mini Piling works directly below or near to existing structures ISBN: 978-0-9545370-0-5 © ASUC: revised March 2015, October 2014 First issued ASUC 2003. ASUC GUIDELINES On safe and efficient Underpinning and Mini Piling works directly below or near to existing structures CONTENTS 1. EXECUTIVE SUMMARY ......................................................................................................................... 3 2. INTRODUCTION ................................................................................................................................... 5 3. DEFINITIONS ........................................................................................................................................ 7 4. TYPES OF UNDERPINNING AND MINI PILING ...................................................................................... 8 5. TECHNIQUES USED IN UNDERPINNING AND MINI PILING WORKS ................................................... 16 6. MINI PILING ....................................................................................................................................... 19 7. GROUND IMPROVEMENT ................................................................................................................. 24 8. TEMPORARY WORKS ......................................................................................................................... 27 9. IMPACT ON OTHERS .......................................................................................................................... 33 10. FACTORS AFFECTING CHOICE OF CONSTRUCTION TECHNIQUE AND METHOD ............................... 37 11. HEALTH AND SAFETY ......................................................................................................................... 39 12. THE PROJECT TEAM ........................................................................................................................... 49 13. PROCUREMENT ................................................................................................................................. 52 14. INSURANCE ....................................................................................................................................... 55 15. GUARANTEES .................................................................................................................................... 59 16. DOMESTIC PROPERTY OWNER CONSIDERATIONS ............................................................................. 61 17. LIST OF APPENDICES .......................................................................................................................... 64 18. APPENDIX A - SITE INVESTIGATIONS .................................................................................................. 65 19. APPENDIX B - BUILDING DAMAGE CLASSIFICATION .......................................................................... 69 20. APPENDIX C - SAFETY HAZARDS AND MITIGATING ACTIONS ............................................................ 69 21. APPENDIX D - HEALTH HAZARDS AND MITIGATING ACTIONS ........................................................... 77 22. APPENDIX E: PLANNING FOR RISK MANAGEMENT –DETAIL ON INFORMATION REQUIRED .......................................................................................................................................... 82 23. APPENDIX F: ASUC UNDERPINNING AND MINI PILING WORKS INDEMNITY GUARANTEE (DIG) POLICY ..................................................................................................................................... 83 24. APPENDIX G: Construction (Design and Management) Regulations 2015 – CDM 2015. ................. 90 25. GLOSSARY OF TERMS......................................................................................................................... 93 26. REFERENCES ...................................................................................................................................... 94 1 SPECIAL NOTE RELATING TO CDM REGULATIONS AND PUBLICATION The principle reason for issuing a 3rd Edition is to enable the section in Appendix G to be added in relation to CDM 2015 and the changes to the law with effect from 6th April 2015. In addition it has enabled changes due to some of the industry comments, for which ASUC is very grateful. Published by ASUC Kingsley House, Ganders Business Park, Kingsley, Bordon, Hampshire GU35 9LU www.asuc.org.uk 2 1. EXECUTIVE SUMMARY 1.1 The Association of Specialist Underpinning Contractors (ASUC) is publishing these guidelines to improve the safety and efficiency of underpinning and mini piling construction to reduce negative impact on others, especially people living or working near to underpinning projects. 1.2 The objective of these guidelines is to enable clients, designers, engineers and others involved in Underpinning and Mini Piling works projects to instruct safe and efficient work. 1.3 Underpinning and Mini Piling works are a complex form of building involving geotechnical, hydrological, structural and civil engineering and health and safety expertise that even those with significant construction experience may not have encountered previously. 1.4 The single leading principle throughout these guidelines is the absolute priority that health and safety has over all other aspects of a project. 1.5 Temporary works (support to existing buildings and to the ground around excavations) is critical and is often overlooked or addressed superficially. 1.6 The main construction techniques used for Underpinning and Mini Piling works structures are mass concrete , pile and beam and/or piled rafts 1.6.1 There are two main types of underpinning: mass concrete underpinning and reinforced concrete (RC) underpinning (underpinning piers with reinforced concrete beams). Mass concrete underpins provide vertical support underneath existing . RC underpins can usually provide vertical support underneath existing walls and retain the ground outside the Underpinning and Mini Piling works . Piers and beams provide a more cost effective solution in some circumstances whereby piers are cast at approx. 3m centres and tied together with an RC beam which is inserted into the existing structure using specialist temporary supports known as “stools” 1.6.2 In Underpinning and Mini Piling works two main types of piles are used; reinforced concrete (RC) bored piles and driven piles. Mini piles are constructed in sections with augers typically 1 m in length; this enables piles up to say 15m deep to be constructed in restricted headroom situations. Driven piles will typically be 100-150mm diameter steel tubes driven either from the top with a percussion drill (like a kango hammer) or more likely bottom driven using a grundomat. A technique used for the spoil less drainage technology in placing gas pipes etc. underground without the need for a lot of excavation.