Which of the three states (solid, liquid, gas) is import for the mechanical properties
Solid
for cohesive soil, the water content is important
What does Vv/ Wv and Vs/ Ws stand for?
The void ratio is 𝑒=Vv/Vs
Is e for loose soil greater or less than for dense soil?
Vv = Volume void (gas + liquid)
Wv= Weight void
Vs = Volume solild
Ws = Weight solid
greater
Which soil Types and corresponding grain sizes are there?
For which kind of soil does liquid change the mechanical properties, and what is the reason for it?
(cohesive soil) clay, silt NOT sand, gravel
The ration of Water “Thickness” to the average grain size is much higher
Fill in the blanks from the American Texture Trinangle
Fill in the blanks for the Grain Size Distribution!
What are the percentages for each soil type of the middle curve?
Curves are monotonously increasing
2: clay 15
silt 35-15=20
sand 97-35=62
gravel 100-97=3
Which 2 techniques enable the separation of different sizes of soil?
sedimentation: put soil into a water cylinder, shake it and the biggest grain will fall the fastest to the ground
sieving: sieves with different grid sizes (finest on the bottom)
What is the Janosi-Hanamoto formula (what relation does it describe)?
Shear-Stress-Shear-Displacement Relation
Pressure Sinkage Relation (Bekker):
describe the influence of b (the smaller dimension of the plate pushing into the ground) on the z (depth) to p (pressure) coordinate system —> drawing two curves with different bs
p = k * z^n
What is the formula for the max Tension on an object experiencing Normal and Tangential Forces
What are the three types of weathering that decreases rocks to grains? With examples.
physical (breakdown by forces)
freezing + melting —> expansion
wind + sand
water
—> no change of chemical structure & mostly larger particles
chemical (reactions mainly of parts of the surfaces)
water H2O
oxygen O2
Acids H3O+
—> change of chemical structure & mostly smaller particles
biological
Categorize the Shape of grains with the sides a, b, c!
How does the realtion between the three axes have to be to obtain
Spherical
Triaxial
Oblete
Prolate
shapes (Zingg-shape types)?
three axes a>b>c (not necessarily one common point of interaction) —> can only roughly describe the shape of the grain
also:
4. a>…>>b≈c
cube is equiaxial
How can the shape of grains be described regarding to Wadell?
real radius divided by the radius of the ideal shape
real surface divided by the ideal surface (obtained from measuring the Volum, calculating radius R)
s/S is for comparison
How can the roughness of the surface grains be measured (according to Powers, Krumbein)?
Describe the 2D illustration of the grain with many circles, then
What is the big difference between the grain shape of silt and sand vs clay
sand and silt: spherical with rough surfaces
clay: bladed/ tabular
what are these formulas?
Mohr-Coulomb
Janosi–Hanamoto
Bekker pressure-sinkage relation
τ_max = (c + σ * tanφ)
τ = τ_max * (1 − e^(-j / K))
j: absolute displacement [length]
K: a soil parameter that represents the shear displacement required to mobilize most of the soil’s shear strength
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