Water Ingress and Reduction Measures in the HRT of the Uma Oma Multi Purpose Project

1. Presented by H. Wannenmacher ; GGE 2016
WATER INGRESS AND
REDUCTION MEASURES
IN THE HRT OF UMA OYA MPP.

2. Project Information – Sri Lanka

3. Uma Oya Multipurpose Project Head Race Tunnel
500 m
1000 m
L= 15‘000 m

4. Water Inflow and Consequences
Dez 2014: Water Inflow of 370 l/s
Drainage of aquifer with settlements and
falling dry of wells on the surface

5. Water Inflow per Section :
24. Dez. 2014 – 370 l/s
Mai . 2015 – 170 l/s
Okt. 2015 – 20 l/s
Water Inflow and Consequences
Grouting

6. Grouting Works: Initial Works- Work Preparation

7. Grouting Works: Initial Works
Injektionsserie
Dichtinjektion Versalstollen II
Injektionsschema A
Dichtinjektion Versalstollen II
Injektionsschema B

8. Grouting Works: Initial Works
Wash Out Effects of Invert Mortar
Wash Out Effects of Pea Gravel
Sealing of Joints
The completion of initial works is a demand to start rock mass grouting !

9. • .
Grouting Works: Initial Works

10. Grouting Works: Rock Mass Grouting

11. Grouting Works: Rock Mass Grouting
• Water Pressure Relief before and after the grouting works

12. Grouting Works: Rock Mass Grouting
Grouting Criteria:
àPmax : 10 bar (above actual ground water pressure)
àVmax : 1000 l per 3 m borehole
àTotal Amount: 565‘000 l for 600 m tunnel section
(cement based grout mixes)

13. Takk!
Thank you for your audience!