Definitions

Question 1

effective stress

Answer 1

inter-granular stress between soil particles

Question 2

pore pressure

Answer 2

stress in pore water (buoyancy)

Question 3

hydrostatic conditions

Answer 3

static - no flow

Question 4

void ratio

Answer 4

volume of voids in volume of solids

Question 5

degree if saturation

Answer 5

how much water occupies void space

Question 6

strain hardening

Answer 6

elastic modulus of soil steadily increases with load

Question 7

preconsolidation pressure

Answer 7

maximum vertical pressure the soil has experienced in the past

Question 8

unconfined aquifer

Answer 8

material not fully saturated so water table can rise and fall

Question 9

confined aquifer

Answer 9

layer of low permeability soil/rock retards the vertical flow of water

Question 10

darcy’s law

Answer 10

q=kiA

Question 11

normally consolidated soil

Answer 11

when current effective stress is the maximum the soil has ever experienced

Question 12

over-consolidated soil

Answer 12

when current effective stress is smaller than the maximum the soil has experienced in the past

Question 13

cohesion

Answer 13

bonds holding particles together: chemical bonds, electrostatic forces, magnetic forces.

Question 14

volumetric dilation

Answer 14

volume increase due to rearrangements of particles due to shear

Question 15

volumetric contraction

Answer 15

volume decreasedue to rearrangements of particles due to shear

Question 16

effect of rapid laoding on pore pressure

Answer 16

water forces particles apart and prevents frictional contact - phi = 0

Question 17

drained conditions

Answer 17

water can flow freely thorugh soiol during loading. change in u = 0

Question 18

undrained conditions

Answer 18

water is not able to flow freely through sample

Question 19

consolidated undrained

Answer 19

stage 1: u = 0; stage 2: u increases

Question 20

unconsolidated undrained

Answer 20

stage 1: undrained stage 2: undrained, phi_u = 0

Question 21

critical state

Answer 21

angle of shearing resistance from shearing at constant volume

Question 22

residual state

Answer 22

when a shear plane is formed in a clay, the adjacent particles tend to align parallel to the plane

Question 23

residual strength

Answer 23

strength exhibiited by clays after shearing to very large displacements.
should be used in situations where large movement has occurred in the past

Question 24

compaction

Answer 24

desnification of soil by mechanical plant such that soil particles pack closer together with a reduction of air voids

Question 25

consolidation

Answer 25

reduction of void volume by removal of water, noirmally due to the application of sustained loading

Question 26

benefits of compaction

Answer 26

increase strength, decrease permeability, decrease compressibility

Question 27

compaction techniques

Answer 27

smooth roller, grid roller, vibrating roller, pneumatic tyred roller, tamping plates

Question 28

in-situ density tests

Answer 28

core cutter, sand replacement test, ballon density test, nuclear method

Question 29

methods for providing resistance force in retaining walls

Answer 29

friction at base (gravity), shete piles, anchoring/nails

Question 30

stress path

Answer 30

graph used to plot successive states of stress for soil element

Question 31

failure envelope

Answer 31

line on mohrs circle or stress path plot used to separate admissible from inadmissible states of stress