Environmental Engineering Reference
In-Depth Information
Figure 18.4.
Grouting downstage with packer (WRC, 1981).
Commonly grout stages will be 5 m to 8 m but may be increased in length lower in the
foundation, e.g. Houlsby (1977) suggests:
Stage
Depth Range (m)
1
0 to 8
2
8 to 16
3
16 to 30
4
30 to 50
While this reduces the number of drill setups and grout hookups, it may result in unnec-
essarily deep holes, particularly for smaller dams.
Smaller than the predetermined stage lengths should be used when:
- Drilling water is lost, indicating a relatively large fracture or opening has been encoun-
tered, or
