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Events at HP04 PK24.862 - Coggle Diagram
Events at HP04 PK24.862
1. Execution
16/02/2020 ~10h00 Technical problem (machine)
Night 15/02/2020 - 16/02/2020 Hyperbaric intervention
2. Construction breakdown
16/02/2020 Ground: extracted materials (60t)
16/02/2020 Ground: settlement, D=1.5m hole, filled with sand-cement
16/02/2020 Movement of cutterhead: blocked
Pursuit of other activites --> Connection in slurry of TBM interrupted for 1.5-2 weeks
16/02/2020 - 08/03/2020 stoppage of TBM
3. Immediate Mitigation
16/02/2020 Slurry circuit: fllush & back-flush
19/02/2020 intervention in bubble to close chimney (equilibriation pipe)
19/02/2020 Complete survey of slurry circuit + trials: V20/21 clogged
19/02/2020 Mechanical check on motors: successful
23/02/2020 Hyperbaric intervention: lower bentonite level in bulkhead -> materials on other side of gate
17/02/2020 Slurry circuit: back-fllush, pipes pop, risk of further damage
4. Mitigation
Date?? New trials to unclog valves + Investigations of surface + nearby utilities disconnected -> trenches are excavated
Modifications on motor
Conclusion: 110 tons fallen in excavation chamber (gradual)
Date?? Soil investigations (cored borehole, destructive boreholes, geophysical survey)
09/03/2020 Restart of cutterhead (slow) --> analysis + materials extracted (50t)
08/03/2020 valves repaired -> new elements are flushed
Monitoring of ground interrupted on 24/02/2020 --> restarted on 09/03/2020
09/03/2020 Materials extracted --> analysis