CAE 370 Study Guide - Final Guide: Clastic Rock, Engineering Geology, Shear Strength
17 May 2018
School
Department
Course
Professor
RACHEL DERADOORIAN --------------------------------
GEOTECHNICAL ENGINEERING FINAL STUDY GUIDE
I. Engineering Geology / Soil Mechanics
a. Geotechnical Engineering
i. Studies the behavior of soil masses subject to various types of forces
ii. Classification of rocks and soil
iii. Establish engineering properties
iv. Ascertain the compressibility
v. Ascertain the shear strength
b. Geology
i. Science of rocks, minerals and subsurface water
ii. The formation and behavior of rocks – the rock cycle
c. Engineering geology
i. Deals with application of geologic principles to geotechnical work
d. Karl Terzaghi
i. Father of modern soil mechanics
e. Rock Types
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2
i. Igneous
1. Formed from the cooling of molten magma / lava
2. Granite, basalt, diorite, andesite
3. Excellent engineering properties
4. Good to build on
ii. Sedimentary
1. Formed by gradual deposition
2. Formed in layers
3. Clastic rocks – sandstone, shale
4. Carbonates – limestone, chalk, dolomite
5. Shear failures can easily occur due to steep bedding planes
6. Sinkholes occur in sedimentary rocks
7. Sandstone has good qualities
8. Hard to excavate
9. Fine grained rocks are not hard to excavate, but are problematic
iii. Metamorphic
1. Formed by alteration of igneous and sedimentary rocks from
pressure and temperature
2. Foliated – slate, schist
3. Non-foliated – marble, quartzite
4. Hardened with heat and pressure
5. Non-foliated are stronger and better to build on
iv. Bedding Planes
1. Layers that are formed in sedimentary rocks
v. Folds
1. Caused by horizontal compressive forces
vi. Fractures
1. Cracks that appear in a rock mass
2. Joints, shears, faults
f. Weathering
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3
i. Physical
1. Disintegration of rocks through physical processes
ii. Chemical
1. Disintegration of rocks through chemical reactions
iii. Biological
1. Disintegration of rocks by biological activities
g. Soil Formation from Parent Rock
i. Residual soil
1. In situ weathering (by physical and chemical agents) of the
parent rock
ii. Transported soil
1. Weathered and transported far away
2. Glacial soils
a. Polished rock surface from moving ice
3. Alluvial soils
a. Carried by water, usually a river
4. Marine soils
a. Carried by oceanic currents or tides
5. Aeolian soils
a. Transported by wind
6. Colluvial soils
a. Slowly formed by creep
b. Quickly formed by landslides or mudslides
II. Site Exploration and Characterization
a. Foundations
i. Deep
1. used when top soil layers have poor load bearing capacity
2. Piles
3. Caisson
ii. Shallow
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Document Summary
Site exploration and characterization: foundations, deep, used when top soil layers have poor load bearing capacity, piles, caisson, shallow. (cid:883)(cid:882)(cid:882: considered undisturbed if ar is less than 10, cpt test, measures the required force to advance the cone, applicable for soft clays and fine to medium sand. = (cid:1839)(cid:1848)(cid:3020)(cid:3050)= (cid:1849)(cid:1848)(cid:3020)(cid:3050: water content, porosity, natural unit weight, saturated unit weight ix. 10 (cid:1874)=(cid:4666)(cid:1830)(cid:2870) (cid:1859)(cid:1853)(cid:1865)(cid:1865)(cid:1853) (cid:1875) (cid:4666)(cid:1871) (cid:1838)(cid:4667)(cid:4667)/(cid:883)8: used to plot a particle size distribution curve, plotted in log scale, correspond to a percent finer of the soil, effective particle size (d10, corresponds to 10% finer soil particles, uniformity coefficient. Cu=d60 / d10: well-graded soils, cu > 4 for gravels, cu > 6 for sands, coefficient of curvature. 12: corresponds to the moisture content required to close the. Casagrande device after 25 blows: plastic limit, moisture content where soil will begin to crack in 3-mm diameter sections ix.
