Geoscience Reference
In-Depth Information
Table 12.6
Diggability index rating (adapted from, Scoble and Muftuoglu, 1984).
Parameter
Symbol
Ranking
Weathering
W
Complete
High
Moderately
Slight
Fresh
Rating
0
5
15
20
25
Strength (MPa): UCS
S
20
20-50
40-60
60-100
100
<
>
Is (50)
0.5
0.5-1.5
1.5-2.0
2-3.5
3.5
<
>
Rating
0
5
15
20
25
Joint spacing (m)
J
<
0.3
0.3-0.6
0.6-1.5
1.5-2
>
2
Rating
5
15
30
45
50
Bedding spacing (m)
B
<
0.1
0.1-0.3
0.3-0.6
0.6-1.5
>
1.5
Rating
0
5
10
20
30
12.7 Diggability classification
•
The Diggability in terms of the type of plant required uses the Index obtained
from the previous table.
Table 12.7
Diggability classification for excavators (adapted from, Scoble and Muftuoglu, 1984).
Class
Ease of
Index
Typical plant which may be used without blasting
digging
(W
S
J
B)
+
+
+
Type
Example
I
Very Easy
40
Hydraulic backhoe
3m
3
CAT 235D
<
<
II
Easy
40-50
Hydraulic shovel or backhoe
3m
3
CAT 235FS, 235 ME
<
III
Moderately
50-60
Hydraulic shovel or backhoe
3m
3
CAT 245FS, 245 ME
>
IV
Difficult
60-70
Hydraulic shovel or backhoe
>
3m
3
:
CAT 245, O&K RH 40
Short boom of a backhoe
V
Very difficult
70-95
Hydraulic shovel or backhoe
4m
3
Hitachi EX 100
>
VI
Extremely
95-100
Hydraulic shovel or backhoe
7m
3
Hitachi EX 1800,
>
difficult
O&K RH 75
12.8 Excavations in rock
•
The assessment of open excavations is different from excavations in limited space,
such as trenches or drilled shafts.
•
Seismic Wave Velocity - SWV
•
Unconfined Compressive Strength - UCS
•
For drilled shafts:
-
Limit of earth auger is 15cm penetration ina5-minute period
→
Replace
with Rock Auger.
- Rock Auger to Down-the-hole hammers (Break).
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