Soils

Soils

1. Soils not bonded like metals

   • non bonded/weak bonding
     • small stress=infinite strain

2. 3 phase material

   • soil classification=size +shapes of partricles so determinese volume of voids
     • sand rock professor jar analogy
     • Does order of soil layering matter too?
     • void/pores filled with liquid/gas/mix
     • affects performance
   • =Soils made of solid(soil) , liquid and air
     • proportion of each affects performance

3. http://www.intelligentcompaction.com/downloads/IC_RelatedDocs/SoilCmpct_Basic%20definitions%20of%20Soils.pdf

4. EXAMPLE:

   • dry=collapse
     • partially saturated = surface tension enough to keep strong
       • saturated =lubricated movement+water displaces space that solids could take so keeps soil fluid
       • how does a meniscus hold soil together

5. when loaded, soils change 3 phase model

   • takes time to change

6. why different to other materials??

   • steel particles strength correlates with larger elements- soils only large units considered

7. 3.0 Nature of Fluid and Particulate Components of Soil

   • if voids are full of water = CAN
   • cant always use fluid mechanics with soils
   • saturated soil can transmit normal stress(if incompressible,increase pressure) but not shear as water has less/low shear strength(resistance to shear)
   • process of soil(main one) - rocks erode, gravity pulls down 'deposits' = stress vertically not always same as horizontal as frictional contact tends to be greater vertically than horizontally
     • since Fx /=/Fy shear force exists

8. SIMPLE SATURATED: effective stress( the stress that keeps the soil rigid)

   • E.S + P.P = TOTAL
     • pore pressure is NOT effective as it works to displace solid particles

9. Drained & Undrained deform response