1. SPECIALISED BLASTING By Mutale Chipoma- Explosives Engineer
Wealth
Unearthed

2. BRIDGE ACROSS LUAPULA RIVER

3. BACKGROUND
AEL invited to conduct blasting under water across the Luapula river
A total of 8 points under water for the construction of abutment pillars were blasted.
The areas to be blasted were surrounded by sheets of steel to keep the water from flowing through.

4. BLAST DESIGN The first area to be blasted was 16m x 16m.
Drilling was achieved by pneumatic drills with hole diameters of 45mm
A walk-way 1m wide was to be left around the blasted area to be used during construction
Holes drilled at 1m burden and spacing
Perimeter holes drilled at 0.5m around the blast area
Hole depth of 1.5m

5. CHOICE OF EXPLOSIVES
The rock at the river bed was classified as medium to soft material and powder factor was selected on this basis
A technical powder factor of 0.39 kg/m3 was selected
A water-proof explosive was needed because blast holes were in water
Magnum bustergel 32 x 200 was selected

6. CHOICE OF EXPLOSIVES CONT’ND
Uncharged collar of 0.5m was left in the main blast holes
Holes charged with five cartridges
Two cartridges tied to cordtex10 at a spacing of 0.8m centre to centre were charged in the perimeter holes.
For the perimeter holes, cordtex10 was used to connect the de-coupled charge only. Initiation was done using Smartdets

7. CHOICE OF INITIATING SYSTEM
In order to reduce vibration , single-hole firing was required
Use of Smartdets was decided upon to achieve single-hole firing and to blast perimeter holes as pre-split together with the ‘production’ holes
Hand lashing using buckets was employed therefore fine fragmentation required

8. CHALLENGES
Choosing a Powder factor to produce fine fragmentation without causing damage to steel works that kept water away
To reduce to minimum the blast induced vibrations so as to keep the steel works intact
Communication difficulties with customer during operations as only one was able to speak English.

9. BLAST PATTERN

10. DRILLED AREA READY FOR CHARGING

11. CHARGING IN PROGRESS

12. TIMING WITH SMARTDETS

13. BLAST AREA CHARGED

14. LAST PILLAR READY FOR CHARGING

15. FRAGMENTATION

16. FRAGMENTATION

17. FIRST PILLAR CONSTRUCTED

18. PILLAR CONSTRUCTED

19. COMPLETED PILLARS ACROSS THE RIVER

20. COMPLETED BRIDGE

21. COMPLETED BRIDGE

22. CUSTOMER SIGN - OFF

23. WITH CUSTOMER

24. Thank You
Thank you