02 - Soil Mechanics Review Continued (1)

02 - Soil Mechanics Review Continued (1) - CEE 452...

Info icon This preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Daniel Rosenbalm, Ph.D., P.E. Geotechnical Services Manager Smith & Annala Engineering Co. June 30, 2016 CEE 452 Foundations
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Agenda Soil Classification Broad classification USCS Index Properties Applied Stresses Compressibility Shear Strength
Image of page 2
Soil Classification Geology Soils classified based upon geologic origin, mineralogy, grain size and shape Engineering Classification based upon engineering behavior There are two broad classes of soils from an engineering perspective: Fine grained and coarse grained soil. The dividing line is the #200 sieve (0.075 mm opening). Broad classification is based upon % by weight passing the #200 sieve.
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
“Fine Grained” Cohesive Soils These include silts and clays. The primary engineering characteristics of these soils are: Water drains slowly from (or flows into) the pores, so excess pore pressures develop when loaded and then dissipate over time as water drains out (or flows in). Time is an important factor in engineering behavior (the time it takes for water to drain from (or move into) the pores and for the excess pore pressure to dissipate). It takes time for all of the settlement (or heave/swell) to occur There may still be some initial undrained (“elastic”) settlement Strength changes with time (as the pore pressure changes) The soil will have short term (“undrained”) strength and long term (“drained”) strength.
Image of page 4
“Fine Grained” Cohesive Soils Soft saturated fine grained soils will want to compress when loaded, developing positive excess pore pressure and expelling water from the pores. Strength will increase with time as the pore water is expelled, excess pore pressures dissipate, and the soil compresses (consolidates). Stiff saturated soils will want to expand in volume (dilate) when sheared , generating negative excess pore pressures. Strength can decrease with time as the negative excess pore pressure dissipates, causing swell (heave or expansion) and a decrease in shear strength. Can have peak and residual shear strength They will still compress under normal loads (though not very much) Unsaturated soils will have negative pore pressures due to capillary action. When free water is available, water will be sucked into the pores, causing swell (heave or expansion) and strength will decrease with time.
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
“Coarse Grained” ( Cohesionless) Soils These include sands and gravels, some coarse, cohesionless silts (“rock flour’). There primary engineering characteristics are : Water drains freely from their pores Very little capillary rise cohesionless soils are usually saturated or essentially dry Time is not generally an issue Pore pressure dissipation and settlement occur essentially instantaneously upon load application Short and long term strength are essentially the same Very rapid loading (earthquakes, blast and impact loads) can be an exception Loose cohesionless soils are contractive (compress when loaded) Dense cohesionless soils are expansive (dilative) when sheared Can get heave in some situations Can have peak and residual shear strength
Image of page 6
“Coarse Grained” ( Cohesionless) Soils
Image of page 7

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern