Geology Reference
In-Depth Information
Rock to Soil and Soil to Rock
Rock to Soil and Soil to Rock
Erosion
Erosion
Sediment
transport
Sediment
transport
Porosity(%)
Porosity(%)
Weathering
of rock to
soil
Weathering
of rock to
soil
0
50
100
0
50
10
sea
sea
1,000
1,000
deposition
dep
osition
Rock
Rock
Selfweight
compaction
Selfweight
compaction
2,000
2,000
Self weight
consolidation
for mud /
mudstone
leads to much
closer packing
Self weight
consolidatio
for mud /
mudstone
leads to muc
closer packin
Soil
Intermediate
Soil
Intermediate
3,000
3,000
Rock
Roc
k
4,000
4,000
Subsiding
Subsid
ing
Mostly vertical, orthogonal
fractures from due to over-
pressure of fluids once
sediment gains some tensile
strength (brittle fracture)
Mostly vertical, orthogonal
fractures from due to over-
pressure of fluids once
sediment gains some tensile
strength (brittle fracture)
basin
basin
Bonding between
mineral grains
Bonding between
mineral grains
Gra
cem
the
tens
true
add
stre
Grain bonding and
cementation leads to
the development of
tensile strength and
true cohesion in
addition to frictional
strength
φ
φ
Cementation from pore
fluids and plastic
migration from highly
stressed grain contacts
Cementation from pore
fluids and plastic
migration from highly
stressed grain contacts
cohesion, c
cohesion, c
Weak sandstone
andsto
ne
We
a
k s
k
Tensile
strength, σ
t
Tensile
strength, σ
t
Normal stress, σ
Normal stress, σ
Clay-rich layer
Cl
y-rich layer
Cla
Figure 1.4 The cycle of rock to soil and soil to rock. Diagenetic and lithi
cation processes cause soft
weathering.
both soil and rock mechanics, which are tools to be adopted, as
appropriate, within the engineering geological model.
1.6 Quali
cations and training
Engineering geologists generally begin their careers as earth science
graduates, later becoming engineering geologists through postgradu-
ate training and experience. Within civil engineering, in many coun-
tries including the UK, Hong Kong and the USA, there is a career
pathway that is measured through achievement of chartered status or
registration as a professional, as summarised in
Table 1.3.
The aim is
that engineering works should only be designed and supervised by
competent persons who have received adequate training and experi-
ence. Chartered or registered status generally requires a recognised
university degree followed by a period of training under the super-
vision of a senior person within a company. The practice of engineer-
ing is often legally de
ned and protected by government regulations.
In some countries, only registered or chartered engineers or engineer-
ing geologists are permitted to use the title and to sign engineering
