Engineering Geo Exam 2

Front 1

Why is the saturation of rocks usually less than that of soils?

Back 1

Rocks have smaller and less pores and are less permeable than soils bc of compaction and cementation

Front 2

Preferable rock characteristics

Back 2

High sp. Grav, high density, lower absorption

Front 3

Why low absorption?

Back 3

Less freeze thaw

Front 4

Specific gravity

Back 4

Indicates how heavy a rock is compared to an equal volume of water

Front 5

What does unconfined compressive strength depend on?

Back 5

Mineral composition, texture, degree of weathering, degree of saturation

Front 6

Tensile strength

Back 6

1/10 compressive strength

Front 7

Brazilian test

Back 7

Tensile strength, disk of sample is put into a compressive machine and fails from tension as it's squished

Front 8

Smaller youngs modulus

Back 8

More deformation

Front 9

Straight line on stress v. Strain plot

Back 9

Elastic deformation (temporary)

Front 10

Curved line of stress v. Strain plot

Back 10

Plastic deformation (permanent)

Front 11

What does poissons ratio tell you?

Back 11

The direction rock will deform

Front 12

LA abrasion test

Back 12

Measures abrasion resistance and is a strength test

Front 13

Specs for LA abrasion test

Back 13

40% for concrete agg., 45% for base course material

Front 14

Sulfate soundness test

Back 14

Durability test, simulates freeze thaw action of water where the growth of crystals acts as the ice

Front 15

Sulfate soundness specs

Back 15

12% for concrete, 15% for base course material

Front 16

Absorption test specs

Back 16

Aggregate fails if absorption is greater than 3%

Front 17

Saturation specs

Back 17

Passes if S <.85

Front 18

Rip rap

Back 18

Large stones and boulders used as a protective layer on the upstream face of earth dams or along river banks to protect shores from erosion

Front 19

Dimension stone

Back 19

Stone cut into specific sizes to be used for facing buildings

Front 20

Flag stone

Back 20

Thinly bedded, slab like pieces of rock frequently used in fire places

Front 21

Strength

Back 21

Resistance to failure

Front 22

Durability

Back 22

Resistance to climatic changes

Front 23

Flat joints

Back 23

Joints parallel to foliation

Front 24

Cross joints

Back 24

Perpendicular to foliation

Front 25

Longitudinal joints

Back 25

Strike parallel to the foliation and dip at steep angles

Front 26

Why is guage dangerous in foundations?

Back 26

Impermeable, hinders the movement of ground water and creates distros hydrostatic heads. Can reduce sliding friction in tunnels along fault plane and once sliding occurs, water behind the gauge will flood the tunnel

Front 27

Popouts and pitting

Back 27

Aggregate particles break in half and pop out, many pop outs create a pit

Front 28

D cracking

Back 28

Water percolate through construction joints and high hydraulic pressure from freezing causes cracks

Front 29

Air entrainment

Back 29

Artificially induced air bubbles in cement paste decreases strength but increases durability

Front 30

Purpose of subsurface investigations

Back 30

To find depth, thickness, comp of soil, location of water table, engineering properties of strata

Front 31

Reconnaissance stage

Back 31

To collect as much available info as possible

Front 32

Exploratory stage

Back 32

Drilling and sampling

Front 33

Auger boring

Back 33

Work in dry, moist soils, provide soil for visual examination and basic lab tests

Front 34

Shelby tube

Back 34

Used for deep, undisturbed samples

Front 35

NX sized diamond bit

Back 35

3" outter diameter, 2 1/8" core diameter

Front 36

What does penetration resistance tell us

Back 36

Indicates the density of cohesionless soils and strength of cohesive soils

Front 37

Spacing of sample holes

Back 37

1 hole per 2500 ft ^2

Front 38

3 ways stratigraphy controls engineering

Back 38

1. Slope angles, 2. More of failure, 3. Drainage

Front 39

Pre splitting

Back 39

Closely spaced holes are drilled and lightly charged, then blasted without millisecond delay and the rock breaks at the desired plane of excavation. Used to minimize overbreak

Front 40

Shot Crete

Back 40

Thick concrete w fine aggregate shot under pressure onto weak rock faces

Front 41

Spacing of holes for highway investigation

Back 41

300 ft

Front 42

Depth of holes for highway investigation

Back 42

6 ft below desired grade and 2/3 max embankment height

Front 43

Rigid pavement system

Back 43

Portland concrete, sub base coyrse, original soil; transfers load through beam action

Front 44

Flexible pavement

Back 44

Asphalt, base course, sub base course, sub grade; load is transferred between particles

Front 45

Plate load test

Back 45

Metal plate is placed on compacted sub grade soil and loaded to 10 psi, settlement in measured

Front 46

California bearing ratio

Back 46

Helps determine thickness of load beating layer of pavement system

Front 47

Fall

Back 47

Travels through air with little to no shear displacement

Front 48

Topple

Back 48

Involved rotational movement, occurs when w/h <tan(theta)

Front 49

Slides

Back 49

Movement occurs along a distinct shear surface or shear zone

Front 50

Driving forces

Back 50

Weight of material, weight of water, weight of structures

Front 51

Resisting forces

Back 51

Shear strength , retaining structures, nailing

Front 52

7 aspects of discontinuities

Back 52

Geometry, continuity, spacing, surface roughness, properties of adjacent rocks, infilling material, presence of water