Introduction to Geotechnical Engineering SU - Fall 2015
- 1. Geotechnical Engineering An Introduction and Personal Insights Michael Harney, P.E., P.Eng. Associate Shannon & Wilson, Inc. mdh@shanwil.com www.shannonwilson.com
- 2. My Background BSCE in Structural Engineering - Purdue University (1998) MSCE in Geotechnical Engineering - University of Washington (2000) Special Certificate in Landslide Risk Assessment and Mitigation – University of Salerno (2006) 15 years experience as a geotechnical engineer
- 3. Geotechnical Engineering When traveling by air (mostly in the U.S., because "What do you do?" is an American question), some people in interesting professions have taken to saying their field is "geotechnical engineering" or some such highfalutin endeavor unintelligible to most people. Should an outlier ask, "What's that?" simply say the explanation would take longer than the flight. Margo Howard (“Dear Margo”)
- 4. Geotechnical Engineering Virtually every structure is supported by the earth. Those that aren’t either fly, float, or fall over… Richard L. Handy (1995)
- 5. Geotechnical Engineering Application of technology to solve problems in, on, or with earth materials
- 16. Challenging? Geology at every site is different – can be complicated even at one site!
- 17. Soils are a 3-phase, particulate material… Solid Air Water Challenging?
- 18. Constitutive Law for Steel Challenging? 𝐹 = 𝑘 ∙ 𝑥 𝜎𝑖𝑗 = 𝐶 ∙ 𝜀𝑖𝑗 or
- 19. Relatively simple constitutive law for soil Challenging? 𝑝 = 𝜎1 + 𝜎2 + 𝜎3 3 𝜎𝑖𝑗 = 2𝜀𝑖𝑗 𝐺𝑠 𝜎𝑖𝑗 𝐺𝑠 𝜎𝑖𝑗 = 𝐺0 𝜎 𝑛 𝑝0 1−𝛽 𝜎 𝑛 2 = 𝜎1 2 + 𝜎2 2 + 𝜎3 2 3 𝐹𝑣 𝜎𝑖𝑗 ∙ 𝜀𝑖𝑗 𝑝 = 𝜀 𝑜 𝑐 𝜎 𝑛 𝑝0 𝛽 − 𝜀 𝑣𝑐 𝑝 = 0 𝐹𝑐 𝜎𝑖𝑗 ∙ 𝜀𝑖𝑗 𝑝 = −3𝑝𝐼𝐼2 + 𝐼𝐼𝐼3 𝐴 𝑥 = 0 𝐼𝐼2 = −𝜎1 𝜎2 − 𝜎1 𝜎3 − 𝜎2 𝜎3 𝐼𝐼𝐼3 = −𝜎1 𝜎2 𝜎3 𝐴 𝑥 = 27 3 + ℎ 𝑥 2ℎ 𝑥 + 3 3 − ℎ 𝑥 ℎ 𝑥 = 𝑥2 4 + 𝑐𝑥 − 𝑥 2 𝑥 = 𝛾 𝑝 ∙ 2𝐺0 𝑝0 𝜎 𝑛 𝛽 𝑝0 𝛾𝑝 = 𝑒𝑖𝑗 𝑝 𝑒𝑖𝑗 𝑝 2 0.5
- 20. Challenging? Local soil variability - Outwash Sand
- 21. Challenging? Local soil variability – Glacial Till
- 23. Challenging? Local soil variability – (Slickensided) Glacial Clay
- 24. Challenging? Local soil variability – Fill
- 25. Challenging? Rock is highly variable – behavior controlled by fractures
- 26. Challenging? A relatively new, developing discipline – New technologies
- 28. Challenging? – New test methods
- 29. Challenging? – New measurement methods
- 30. Challenging? – New visualization tools
- 31. Challenging? – New analytical methods
- 32. Challenging? A relatively new, developing discipline – New fields: • Waste disposal and containment • Site remediation and environmental enhancement • Deep ocean, cold regions and space geotechnics • Natural hazard protection and risk reduction (landslides, tornadoes, hurricanes, tsunamis, expansive soils, floods) • Seismic safety – mitigation of seismic risk • Energy • Preservation and restoration of old structures • Sustainable geotechnics
- 33. Geotechnics Integration of geology and civil engineering A joint effort: • Geotechnical engineers • Geological engineers • Engineering geologists • Geophysicists • Hydrogeologists • More… (geochemists, seismologists, mining engineers…)
- 35. Complex Geology
- 36. Complex Geology
- 37. Complex Geology
- 38. Earthquakes
- 39. Historic Seattle Shoreline and Fills 1874 1893 1901 Post WWII
- 40. Liquefaction
- 41. Landslides Why? • TOPOGRAPHY • GEOLOGY • WATER • WATER • WATER • HUMAN ACTIVITIES • EARTHQUAKES
- 42. Landslides
- 43. Local Projects
- 44. Local Projects
- 45. Local Projects
- 46. Local Projects
- 47. Local Projects
- 48. Local Projects
- 49. Local Projects
- 50. Local Projects
- 51. A Typical Project • A new underground combined sewer overflow storage tank
- 52. A Typical Project • A new underground combined sewer overflow storage tank
- 53. • A new underground combined sewer overflow storage tank
- 54. • How do we make the excavation?
- 55. A Typical Project • What properties or behavior of the ground will be important to design the tank? – Can the ground support the applied load? – How will the ground deform under load? – How much pressure will the ground apply to the walls? – How much pressure will the groundwater apply to the walls? – How much water will flow into our excavation? – How will we excavate the ground?
- 57. • Surface exposures (outcrops)
- 59. • Downhole geophysics – map bedrock fractures
- 60. • Downhole water pressure tests
- 61. • Review rock core
- 62. A Typical Project • Laboratory testing – what do we need to know about the rock? – Strength – Deformability – Joint strength – Behavior when excavated
- 63. • Laboratory testing – rock strength
- 64. • Laboratory testing – rock joint strength
- 65. • Laboratory testing – rock degradation • •
- 66. • Prepare boring logs
- 67. • Map rock discontinuities - stereonets
- 68. A Typical Project • Subsurface characterization
- 70. • Recommendations – load on the walls
- 71. • Recommendations – uplift resistance
- 72. • Recommendations – dewatering
- 73. • Recommendations – instrumentation
- 74. • Construction
- 75. • Construction
- 76. • Construction
- 77. • Construction
- 78. • Construction
- 79. • Construction
- 80. • Construction
- 81. • Construction
- 82. • Construction
- 83. Opportunities for Geotechnical Engineers • Consulting firms • Environmental agencies • Contractors • Geo-resource firms • Oil industry • Federal & State labs/agencies • Research, teaching
- 84. Geotechnical Career • 0 to 2 years – About 80% in the field (outdoors) – 20% lab testing, logs, profiles, some writing…
- 85. Geotechnical Career • 2 to 5 years – About 50% in the field – Other • Lab Testing • Logs/Profiles • Calculations • Report Writing • Meetings – Start learning project management
- 86. Geotechnical Career • 5 to 10 Years – About 20% in the field – Responsible for Design – Manage small to medium projects
- 87. Geotechnical Career • > 10 years – Manage all types of projects – Manage and mentor younger staff – Perform marketing to get more work
- 88. Geotechnical Career • > 10 years
- 89. So you want to… • MSCE in Geotechnical Engineering • BS in related field (BSCE preferred) • Broad background – Civil engineering: structures, hydro, pavements – Environmental: contaminants, transport, remediation – GIS • Geology! • EIT, PE
Editor's Notes
- #4: Dear Corn: The way to get yourself out of these conversations is not to get into them. Because you are referring to people you've just met, I offer you The Airplane Trick. When traveling by air (mostly in the U.S., because "What do you do?" is an American question), some people in interesting professions have taken to saying their field is "geotechnical engineering" or some such highfalutin endeavor unintelligible to most people. Should an outlier ask, "What's that?" simply say the explanation would take longer than the flight. -Margo