Guidelines for Performing Foundation Investigations for Miscellaneous Structures U.S. Department of the Interior Bureau of Reclamation December 2004 Guidelines for Performing Foundation Investigations for Miscellaneous Structures Technical Service Center Denver, Colorado 2004 United States Department of the Interior Bureau of Reclamation MISSION STATEMENTS The mission of the Department of the Interior is to protect and provide access to our Nation’s natural and cultural heritage and honor our trust responsibilities to tribes. The mission of the Bureau of Reclamation is to manage, develop, and protect water and related resources in an environmentally and economically sound manner in the interest of the American public. Any use of trade names and trademarks in this publication is for descriptive purposes only and does not constitute endorsement by the Bureau of Reclamation. The information contained in this document regarding commercial products or firms may not be used for advertising or promotional purposes and is not to be construed as an endorsement of any product or firm by the Bureau of Reclamation. Acknowledgements Michael Szygielski and Jeffrey Farrar of the Earth Sciences and Research Laboratory, Technical Service Center, Denver, Colorado wrote this manual. Numerous sources of information were used, including sources from the Bureau of Reclamation and authoritative geotechnical engineering text books. Allen Kiene and Robert Davis of the Geotechnical Services Group performed a technical review of this manual, along with Richard Fuerst and Stephen Robertson of the Water Conveyance Group. The editor was Lelon A. Lewis. We hope that this document will be useful to all area offices, construction offices, regional geology and engineering offices, and geologists and geotechnical engineers in the Bureau of Reclamation, as well as geotechnical engineers worldwide. Contents page Acknowledgements ...............................................................................................................iii Scope .......................................................................................................................................xi Introduction ............................................................................................................................1 Chapter 1—Foundation Considerations for Structures....................................................3 1.1 Point Structures ..........................................................................................................3 1.2 Line Structures............................................................................................................4 1.2.1 Canals....................................................................................................................4 1.2.2 Pipelines ...............................................................................................................5 1.3 Roadways.....................................................................................................................8 1.4 Backfill Materials ........................................................................................................9 Chapter 2—Background Study...........................................................................................11 2.1 Soil Characterization ................................................................................................11 2.2 Maps and Photo Information.................................................................................16 2.3 Surface Land Form Types.......................................................................................16 2.3.1 Surface Water ....................................................................................................16 2.4 Subsurface Considerations......................................................................................16 2.4.1 Soils.....................................................................................................................17 2.4.2 Ground Water ...................................................................................................18 2.5 Existing Structures ...................................................................................................19 2.5.1 Adjacent Structures...........................................................................................19 2.5.2 Road Cuts and Fills...........................................................................................19 Chapter 3—Site Investigation.............................................................................................21 3.1 Initial Surface Site Reconnaissance........................................................................21 3.2 General Considerations for Specific Site Investigations.....................................21 3.2.1 General...............................................................................................................21 3.2.2 Surface Water ....................................................................................................22 3.2.3 Ground Water ...................................................................................................22 3.2.4 Sampling Depth ................................................................................................23 3.2.5 Soil Engineering Properties.............................................................................23 3.2.5.1 Soil Property Correlations........................................................................24 3.2.5.2 Permeability................................................................................................30 3.2.5.3 Compressibility..........................................................................................38 3.2.5.4 Strength.......................................................................................................44 3.2.6 Bearing Capacity of Structures........................................................................49 3.2.7 Settlement ..........................................................................................................51 3.2.8 Slope Stability ....................................................................................................55 3.2.9 Seismic Stability.................................................................................................61 3.2.10 Backfill Material ..............................................................................................61 3.3 Surface Investigations..............................................................................................64 3.3.1 Surface Geophysics ..........................................................................................64 v Guidelines for Performing Foundation Investigations for Miscellaneous Structures 3.4 Subsurface Exploration ...........................................................................................65 3.4.1 Test Pits and Dozer Trenches ........................................................................71 3.4.2 Hand Auger .......................................................................................................72 3.4.3 Standard Penetration Resistance Testing ......................................................73 3.4.3.1 Other Drive Sampling and Penetration Tests.......................................78 3.4.3.2 Becker Penetration Test...........................................................................78 3.4.4 Cone Penetration Testing................................................................................78 3.4.5 Drilling—Power and Bucket Augers .............................................................80 3.4.6 Rotary Drilling—Hollow-Stem Auger...........................................................83 3.4.7 Rotary Drilling—Samplers ..............................................................................84 3.4.8 Rotary Drilling—Diamond Rock Coring......................................................84 Chapter 4—Problem Soils ..................................................................................................87 4.1 Silts and Low Plasticity Soils...................................................................................87 4.2 Clays ...........................................................................................................................93 4.2.1 Firm, Consolidated Clays.................................................................................93 4.2.2 Compressible Clays...........................................................................................93 4.2.3 Expansive Clays ................................................................................................94 4.3 Sands...........................................................................................................................97 4.4 Liquefaction...............................................................................................................97 4.5 Gravels .......................................................................................................................97 4.6 Rock............................................................................................................................99 4.7 Shales..........................................................................................................................99 4.8 Loessial Soil...............................................................................................................99 4.9 Organic