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2012 ACES/IES For Qualified Site Supervisors (QSS) 1st Edition Sep 2012 Foundat

2012 ACES/IES For Qualified Site Supervisors (QSS) 1st Edition Sep 2012 Foundation Supervision Guide Foundation Supervision Guide For Qualified Site Supervisors (QSS) Published by: ASSOCIATION OF CONSULTING ENGINEERS SINGAPORE INSTITUTION OF ENGINEERS, SINGAPORE Foundation Supervision Guide 2011 3 Foundation Supervision Guide For QSS - REs and RTOs Table of contents Section 1: Introduction Section Page 1.1 Scope 8 1.2 Pre-Construction/ Pre-Condition Survey 9 1.3 Setting Out 9 1.4 Site Investigation Report 9 1.5 Safety, Nuisance and Damage 9 Section 2: Deep Foundation Works Section Page 2.1 General roles and duties of QSS in Deep Foundation Works 10 2.2 Setting Performance Criteria and Tolerances 11 2.3 Foundation Schedules and Drawings 12 2.4 Damage to Underground Services 12 2.5 Non-Displacement Piles (including Barrettes and Diaphragm Walls) 13 2.5.1 Quality Control in Piling Work 13 2.5.2 Noise Nuisance 27 2.5.3 Damage to Adjacent Structures 28 2.5.4 Damage to Piles 28 2.6 Displacement Piles 28 2.6.1 Quality Control and Site Installation Works 30 Foundation Supervision Guide 2011 4 2.7 Testing of Piles 34 2.7.1 Integrity Testing of Piles 34 2.7.2 Static Load Testing of Piles 35 2.7.3 Pile Instrumentation 48 Section 3: Shallow Foundation Works Section Page 3.1 Safety of Excavation 49 3.2 Trial Pits 49 3.3 Inspection of Founding Soil Layer 49 3.4 Soil Bearing Pressure Tests 50 3.5 Existing Structures and Services 52 3.6 Over Excavation 52 3.7 Dewatering 52 3.8 Excavated Materials 53 3.9 Standard Checklist for Shallow Foundation 53 3.10 Backfilling 53 Appendices Section Page Appendix 1 Checklist for Displacement Pile 55 Appendix 2 Displacement (Driven) Pile Record 56 Appendix 3 Non-Displacement Pile Record 57 Appendix 4 Checklist for Static Pile Load Test using Kentledge Stack 58 Appendix 5 Pile Load Test Record 61 Foundation Supervision Guide 2011 5 Acknowledgements: 1. Surbana International Consultants Pte Ltd 2. Joint Accreditation Committee (JAC), namely: i) Building and Construction Authority (BCA) ii) Association of Consulting Engineers Singapore (ACES) iii) Institution of Engineers Singapore (IES) The retail price for this book is $20. MATERIALS IN THIS GUIDE HAVE BEEN CONTRIBUTED BY RESOURCES SUPPLIED BY THE ABOVE. This guide shall serve only as a quick guide to facilitate construction supervision for Resident Engineers (RE) and Resident Technical Officers (RTO). RE and RTO must still refer to approved drawings, building specifications, codes, other relevant documents and relevant authorities’ requirements for the execution of the works. Technical Editor: Er. Kok King Min Foundation Supervision Guide 2011 6 Foreword by President, ACES The importance of our QSS as part of our consultancy work cannot be underestimated in the Built Environment. We depend heavily on the professionalism of our QSS on the ground to help ensure that our designs are followed through on sites and the products delivered safely and according to specifications to our ultimate clients. In this regard, I must commend the JAC for the superb work that they have contributed in these two sets of guide books that will assist our QSS in their daily work. This is part of the journey towards even more professionalism in our work and I look forward to more such initiatives in the Built Environment. Thank You. Er. Koh Boon Liang President Association of Consulting Engineers Singapore Foundation Supervision Guide 2011 7 Foreword by President, IES Dear Resident Engineer / Resident Technical Officer, A good and solid foundation is the core of any building structure, without which no building will be able to stand firm. Compromised foundation and building quality will be undermined if site supervisors do not adhere to the stipulated guidelines lay down by the authorities. The aim of this Foundation Supervision Guide is to familiarise the site supervisors with the correct and proper procedures when doing foundation work such as deciding on the choice of foundation systems to be used, pre-construction survey, testing of piles, ensuring that foundation works do not have undesirable impact on adjacent structures or services, etc. This Guidebook has been divided into three sections: Section 1 is an introduction to foundation and piling at construction worksites; section 2 touches on deep foundation works while the final section looks at shallow foundation works. REs and RTOs will be able to pick up the necessary information from this guidebook for application in their daily work. We would also like to thank Er. Kok King Min for editing this Foundation Supervision Guide. Er. Ho Siong Hin President The Institution of Engineers, Singapore Foundation Supervision Guide 2011 8 Section One – Introduction 1.1 Scope The choice of foundation system depends on the types of the proposed development, the anticipated loadings and on the strength and stiffness of the ground strata. In general, the foundation system must satisfy the following two principles: i. Adequate factor of safety against Ultimate Limit State Criteria. i.e. To transmit the worst possible combinations of dead, live, lateral or other forms of loads from the structure to the ground without causing soil or foundation failure. ii. Adequate factor of safety against Serviceability Limit State Criteria. i.e. To withstand the design load without causing excessive total settlement and such that differential settlement is within tolerable limits. The proposed foundation works should not give rise to undesirable effect on adjacent structures or services. The choice of a particular type of foundation depends on the column load, ground conditions, availability of foundation materials and acceptable workmanship, environmental considerations and the constraints of the site. Issues on site with regards to the supervisory and interfacing roles of the QSS with the other stakeholders such as the Builder, Builder's PE and the design Qualified Person (QP) in foundation works would be discussed in this guide. Foundation Supervision Guide 2011 9 1.2 Pre-Construction/ Pre-Condition Survey • Pre-construction/ Pre-condition survey shall be carried out by the builder on the surrounding buildings or structures before execution of works • This helps the builder to differentiate and identify the damages that could arise from the proposed works • Whenever the QP deemed necessary, selected monitoring measures shall be carried out during the course of the works • The builder shall carry out all necessary protective and strengthening measures to ensure that surrounding structures and facilities are not damaged 1.3 Setting Out • Sufficient lines and level pegs to enable each column, footing, pile, etc., to be accurately positioned shall be set out by the builder • The site supervisor shall check the accuracy of the setting out • Certification from a registered surveyor shall also be obtained for the setting out of foundations • The responsibility of the setting out shall lies with the builder 1.4 Site Investigation Report • A set of site investigation report shall be kept on site 1.5 Safety, Nuisance and Damage • Reference shall be made to the statutory provisions in the Building Control Act and Regulations, the Workplace Safety and Health Act and the Environmental Pollution Control (Control of Noise at Construction Sites) Regulations Foundation Supervision Guide 2011 10 Section Two - Deep Foundations Works Deep foundation work includes the construction of structural elements in the soil for transferring of superstructure loadings through weaker or compressible soil strata onto a stiffer bearing layer beneath the surface. This section covers the general supervision requirements of all types of deep foundation systems but is not limited to small and large displacement driven piles, non-displacement bored piles, barrettes or diaphragm walls. 2.1 General roles and duties of QSS in Deep Foundation Works The following items shall be supervised and controlled during the various phases of construction: • Check the location of proposed deep foundations, materials, reinforcement cages (dimensions, assembly and length) and other elements • Determination of penetration depth based on actual site conditions under the direction of the QP • Check foundation eccentricities plan and report to QP (where applicable) • Obtain soil sample at every 3m (approximate) interval • Keep records of all works done, including records of tests, inspections, status of work, material tests, etc. on site • Check overall building orientation, dimensions and corner pegs as set out by registered surveyor • Check platform levels before commencing works and after backfilling • Check that steel cover and other materials are in accordance to specifications / drawings • Take level of pile or barrette before and after load test • Standing supervision to ensure boring operation is installed according to the approved method statement (concrete characteristics; concrete placement: quantity, duration, rise and final level recovery of the tremie pipe, etc.) • Keep a complete record of every foundation installed (Refer to the recommended forms and checklist in the Appendices) Foundation Supervision Guide 2011 11 • Check ready-mixed concrete plant batching time for concrete delivered to the site (usually less than 2 hours including concreting into bored hole) 2.2 Setting Performance Criteria and Tolerances • QP shall set the performance criteria • Settlement of a deep foundation member depends on the load distribution between the shaft and the base • Pile group effects could also govern the settlement of working piles • Specific requirements of the structure could influence the total tolerable settlement and differential settlements • uploads/Management/ guide-foundation-supervision.pdf