Environmental Engineering Reference
In-Depth Information
Flow
rate
Flow
rate
Laminar flow
Turbulent flow due to
open fractures or flow
past packer
Effective
pressure
Effective
pressure
Flow
rate
Flow
rate
Expansion of
fracture in rock
or hydraulic
fracturing
of rock
Washing out of
filling in fracture
Effective
pressure
Effective
pressure
Flow
rate
Flow
rate
Progressive scour
out of fracture
Blocking of fissure
or swelling of rock
Effective
pressure
Effective
pressure
Figure 5.36.
Typical effective pressure versus flow curves for packer tests.
Figure 5.36 shows examples of plots indicating these types of behaviour.
5.15
USE OF SURFACE SURVEY AND BOREHOLE INCLINOMETERS
5.15.1
Surface survey
In the investigation of dam sites and the assessment of existing dams the precise measure-
ment of location and elevation of the ground surface provides information on:
-
Existing mass movement - e.g. landsliding;
-
Foundation settlement;
-
Deformation or displacement of structures.
A range of surface survey methods is included in
Table 5.7
.
The development of computer assisted survey instruments has enabled the determination
of the position of many surface points to be carried out rapidly and with great accuracy.
A vital component of any dam investigation should be the establishment and regular meas-
urement of a network of surface stations. Survey marks should be founded below the level
of reactive soil and away from traffic. The points should be clearly marked and numbered.
