lecture 7

Question 1

subsidence

Answer 1

downwards movement of ground

Question 2

macro voids

Answer 2

larges caves

Question 3

micro voids

Answer 3

small caves

Question 4

what are the three main ground types at risk of subsidence

Answer 4

clay, limestone and mine works

Question 5

why is clay at risk of subsidence

Answer 5

its particles are flat which means they get squashed under a load

Question 6

what is meant by the term expansive

Answer 6

particle that can absorb and release water causing them to swell and shrink

Question 7

what is smectite

Answer 7

a group of mineral found in clay

Question 8

what is montmorillonite

Answer 8

the main smectite mineral that absorbs the most water

Question 9

what is meant by consolidation

Answer 9

when soil reduces in volume under a load and water in removed

Question 10

what is meant by compaction

Answer 10

when air in removed from the soil under a load (becomes denser)

Question 11

what is a settlement

Answer 11

downwards movement of a structure

Question 12

what are the 2 types of settlement, explained

Answer 12

uniform: the whole structure moved downwards at the same rate
differential: one corner moves downward faster

Question 13

name some of the main mining techniques

Answer 13

longwall
pillar and stall
stoping
solution
opencast/quarry