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  • State of California Department of Transportation Engineering Service Center

    Division of Structures

    Foundation Manual

    Issued By Offices of Structure Construction

    November 2008

  • ________________________________________Acknowledgements

    November 2008

    Caltrans Foundation Manual Acknowledgements

    Acknowledgements The 2008 edition of the Foundation Manual was updated by a group of dedicated Senior Bridge Engineers from the Offices of Structure Construction (OSC). Thanks to Rich Foley, P.E., OSC Substructure Committee Chairman, for his contributions and leadership. Thanks to the OSC Substructure Committee members for their valuable contributions and teamwork. Members include: Daniel Dait, P.E., David Keim, P.E., Jeff Kress, P.E., John Walters, P.E., and Mark Woods, P.E. Thanks to Roman Granados, HQ Office Associate for his contributions and hard work. Thanks to Mike Beauchamp, P.E., Supervising Bridge Engineer, OSC Substructure Committee Sponsor, for his contributions and sound guidance. Special thanks to the Caltrans engineers who drafted the original 1984 Foundation Manual and to the Caltrans engineers who drafted the 1996 revision. Their vision, dedication, and research, produced a manual that has been used throughout the Department. Signed,

    Rob Stott, P.E. Principal Bridge Engineer Deputy Division Chief OSC California Department of Transportation

  • _________________________________________ Preface

    November 2008

    Caltrans Foundation Manual Preface

    Preface The Foundation Manual is intended to provide the field engineer with information that may be of some assistance in solving foundation problems and in making engineering decisions. Although the field engineer is required to make engineering decisions throughout the life of a construction project, none is probably more important than the engineers decision regarding the suitability or unsuitability of the foundation material supporting a spread footing foundation. The engineer must decide if the foundation material encountered at the planned bottom of footing elevation is, in fact, representative of the material shown on the Log of Test Borings sheet and therefore suitable for the imposed loads. If not representative, the engineer must decide what action to take. This is not to minimize the importance of pile supported foundations, which have their own unique problems that require decisions based on sound engineering judgement. What action does the engineer take when pile bearing capacity is not obtained at specified tip or reaches refusal ten feet above tip elevation? All types of foundations are discussed in the manual along with related problems and possible solutions. There is no one solution that will always solve a particular problem. Each situation must be reviewed and a decision made based on the available data and ones own experience. There is no substitute for utilizing sound engineering judgment in solving engineering problems. If all problems are solved in this manner, then the engineer can be confident that a good solution was used to solve the problem.

  • _________________________________________Table of Contents

    November 2008

    Caltrans Foundation Manual Table of Contents-1

    TABLE OF CONTENTS Chapter 1 Foundation Investigations 1-1 Introduction 1-1 Who Performs Foundation Investigations 1-2 Foundation Investigation Overview 1-3 Subsurface Drilling Operation 1-4 Log of Test Borings 1-5 Foundation Report 1-6

    Applicability of the Log of Test Borings and Foundation Report to the Contract 1-7

    Basic Soil Properties 1-7 Geotechnical Drilling and Sampling Equipment 1-9 Chapter 2 Type Selection 2-1 Chapter 3 Contract Administration 3-1 Footing Foundations 3-5 Pile Foundations 3-6 As-Built Drawings and Pile Records 3-8 Differing Site Conditions 3-9 Chapter 4 Footing Foundations 4-1 General 4-1 Types 4-1 Bearing Capacity 4-3 Failure Modes 4-4 Factors Affecting Bearing Capacity 4-6 Settlement 4-10 Ground Improvement/Soil Modification 4-10 Construction and Inspection 4-11 Excavations 4-12 Open Excavations 4-13 Cofferdams or Shored Excavations 4-15 Wet Excavations 4-17 Bottom of Excavation Stability 4-19 Foundation Inspection & Construction Considerations 4-20 Foundation Problems and Solutions 4-22 Disturbed and/or Contaminated Material 4-23 Unsuitable Foundation Material 4-23

    Modifications Due to Disturbed, Contaminated or Unsuitable Material 4-24

    Safety 4-26

  • _________________________________________Table of Contents

    November 2008

    Caltrans Foundation Manual Table of Contents-2

    Chapter 5 Pile Foundations General 5-1 Introduction 5-1 Specifications 5-1 Cast-in-Place Piles 5-2 Driven Piles 5-3 Alternative Piles 5-4 Chapter 6 Cast-in-Place Piles 6-1 Description 6-1 Specifications 6-2 Drilling Equipment 6-2 Drilling Methods 6-10 Drilling Problems 6-10 Inspection and Contract Administration 6-12 Pile Defects 6-15 Safety 6-20 Chapter 7 Driven Piles 7-1 Introduction 7-1 General Specifications 7-2 Pile Driving Definitions 7-4 Hammer Types 7-11 The Drop Hammer 7-12 Single Acting Steam/Air Hammer 7-13 Double Acting Steam/Air Hammer 7-14

    Differential Acting Steam/Air Hammer (External Combustion Hammer 7-16

    Diesel Pile Hammers 7-17 Vibratory Driver/Extractor 7-21 Hydraulic Hammer 7-23 General Hammer Information 7-24 Nominal Resistance/Bearing Capacity 7-25 Pile Load Testing 7-26 Dynamic Analysis by Wave Equation 7-26 Manufacturers Energy Ratings 7-29 Battered Piles 7-30 Preparing to Drive Piles 7-30 Verification of Hammer Energy 7-32 Materials Checklist 7-33 Steel Piles 7-33 Timber Piles 7-34 Logging of Piles 7-34 Driving Challenges 7-36

  • _________________________________________Table of Contents

    November 2008

    Caltrans Foundation Manual Table of Contents-3

    Difficult or Hard Driving 7-36 Soft Piles and Re-Drive 7-39 Alignment of Piles 7-41 Overdriving 7-41 Safety 7-42

    Chapter 8 Static Pile Load Testing & Dynamic Monitoring 8-1

    Introduction 8-1 Reasons For Static Load Testing and Pile Dynamic Analysis 8-1 Static Pile Load Tests 8-3 Pile Dynamic Analysis (PDA) 8-4

    Contract Administration of Static Pile Load Testing & Pile Dynamic Analysis 8-6

    Inspection Requirements During Static Load Testing and PDA 8-7 Chapter 9 Slurry Displacement Piles 9-1 Introduction 9-1 History 9-1 Slurry Displacement Method 9-2 Principles of Slurry Usage 9-4 Sampling and Testing Drilling Slurry 9-8 Density 9-10 Sand Content 9-11 pH Value 9-12 Viscosity 9-12 Types of Slurry 9-13 Water 9-14 Mineral 9-15 Synthetic 9-20 Equipment 9-25 Specifications 9-29 Minimum Pile Diameter Requirements 9-29

    Concrete Compressive Strength & Consistency Requirements 9-30

    Slurry Testing and Cleaning Requirements 9-30 Pile Acceptance Testing Access Requirements 9-33 Pile Concrete Placement Requirements 9-33 Inspection and Contract Administration 9-35 Pile Acceptance Testing 9-38 Defective Piles 9-41 Pile Mitigation and Acceptance 9-45 What Happens When a Pile is Rejected 9-45 Pile Mitigation Methods Repairs, Replace, Supplement 9-45

  • _________________________________________Table of Contents

    November 2008

    Caltrans Foundation Manual Table of Contents-4

    Pile Mitigation Plan Development and Approval Procedures 9-48

    Responsibilities of the Engineer 9-48 Responsibilities of the Contractor 9-49

    Responsibilities of the DES Pile Mitigation Plan Review Committee 9-51

    Pile Mitigation Field Procedures and Pile Acceptance 9-52 What to Expect in the Field During Pile Mitigation 9-52

    Procedures For Approving the Pile Mitigation Work Performed in the Field and Pile Acceptance 9-53

    Safety 9-53 Chapter 10 Pier Columns 10-1 Description 10-1 Specifications 10-2 Construction Methods 10-2 Excavation 10-2 Problem Areas 10-3 Safety 10-4 Chapter 11 Tiebacks, Tiedowns & Soil Nails 11-1 Introduction 11-1 Tiebacks 11-1 Components 11-1 Sequence of Construction 11-3 Safety 11-4 Tiedowns 11-4 Sequence of Construction 11-5 Testing of Tiebacks and Tiedown Anchors 11-6 Performance Tests 11-7 Proof Tests 11-7

    General Acceptance Criteria Proof & Performance Tests 11-7

    General Construction Control 11-8 Soil Nails 11-8 Sequence of Construction 11-10 Engineers Responsibility 11-11 Contractors Responsibility 11-11 Testing of Soil Nail Walls 11-11 Verification of Nails 11-11 Proof Testing 11-12 Supplemental Testing 11-12 Safety 11-12

  • _________________________________________Table of Contents

    November 2008

    Caltrans Foundation Manual Table of Contents-5

    Chapter 12 Cofferdams and Seal Courses 12-1 General 12-1 Sheet Piles and Bracing 12-1 Excavation 12-5 Seal Course 12-5 Concrete Deposited Underwater (Tremie Placement Method) 12-6 Seal Course Inspections 12-7 Thickness of Seal Course 12-7 Contractors Responsibility 12-8 Engineers Responsibility 12-8 Dewatering 12-8 Safety 12-9 Chapter 13 Alternative Piles and Special Considerations 13-1 Introduction 13-1 Micropiles 13-1 Micropile Definition and Description 13-1 Applications 13-2 Caltrans Applications 13-3 Seismic Retrofit 13-3 Earth Re


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