The document discusses risks associated with an underground metro project and strategies to mitigate those risks. It identifies key risks in engineering, construction, procurement, and execution phases. It analyzes specific risks that occurred, such as a diaphragm wall trench collapse and cavity formation in diaphragm walls. Mitigation strategies are proposed, such as modified excavation sequences, installation of bore wells, and micro-concrete grouting. Overall project risks are assessed using a risk matrix. Innovations to construction methods are also discussed to streamline utility diversion and reduce risks of soil collapse and sink holes.

1. Project
Execution
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one step towards project management excellence...
Palla Narasimhudu

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Introduction:-

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Objectives:-
Identify, Analyze the Risk Factors
Perform Qualitative and Quantitative Analysis
Plan for Risk Mitigation
Monitor and Control throughout the project life cycle
Control of future risks and Pro-activeness
Develop Risk Response strategies and Contingency plans for unexpected
Risk register for further similar projects

4. Scope :-
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5. Risks in EPC Project:-
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Engineering
• Project Feasibility
• Viability
• Technology selection
• Design
• Joint venture
• Geographical
conditions
• Funding
Construction
•Utility and Traffic diversion*
•Survey works
•Diaphragm Walling*
•Excavation
•Decking and steel struts*
•Tunnel mining and cross passage*
•Accidents/ Losses of lives
•Non- availability of manpower
•Confined space
•Quality
•Clarity less communication
•Soil condition
•Bad Infrastructure
Procurement
• Underestimate the
need
• Quality supplier
selection
• Offers fail to meet the
needs
• Insufficient funds
Unforeseen
• Sudden collapse of soil
• Heavy rains and floods
• Sudden settlements
• Extreme temperature
Execution
• Delay in land acquisition
• Inexperience project
management/ team
• Ineffective decomposition
of work
• Regulatory issues
• Failure to forecast
• Design changes
• Stake holder management
• Safety/ Environmental
• Political
• Decision making
• Currency / commodities
fluctuation
*varies for different projects

6. 228m
24m19m
228m
24m19m
228m
24m19m
EGMORE NEHRU PARK KMC PACHAIPPA SHENOY
NAGAR
Station Length = 228m + 228m + 228m = 684m
Tunnel Length = 947m + 573m + 898m + 966 = 3384m
22m 22m 24m
Cross Passage = 3nos + 2nos + 3nos + 3nos = 11nos
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Case Study- UAA-04 CMRL Project

7. Risk identification and action plans- UAA-04
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Existing Diverted-1 Diverted-2
Impact- Road diversion and D-Wall Construction
Mitigation-
1) Stage wise diversion
2) Interchange and inter-displacement of utilities for D-Wall construction
Risk-
Space constraint in Utility diversion
Utilities running across station

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Risk-
Space constraint in traffic diversion
Impact-
D-Wall Construction
Shaft Handover for TBM launching
Mitigation-
1) Stage wise diversion
2) Decking for traffic

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UG Metro Station - Plan
20m 20m
40m
60m
Risk- Excavation with strut Impact- Possible Delay in shaft handover for TBM launch
Mitigation-
1) D-Wall design change without strut
2) Modified excavation sequence of 12m max with additional centre opening
12m

11. Post Risk Analysis-
• Poly-mud level was 1.5mt below the Ground Level
• Due to heavy rain there was contamination of seepage water and polymer properties may reduce which may be
insufficient to withstand the top loose strata
• Continuous rain, rise in ground water level immediately below the guide wall due to the heavy rain, higher than the
poly-mud level
• Vibration due to chiselling
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Diaphragm Wall Trench Collapse- P147
Impact-
1) Progress hamper for other panels
2) Plan for mitigation
Mitigation-
1. Bund making over the guide wall and Keeping poly-mud level always
higher than the GW level
2. Equal quantity of crusher dust was stoked for immediate risk mitigation.
Immediate risk response-
Collapsed trench filled with M5 grade concrete
Bund
Risk factor-
Likelihood- 0.25
Potential impact- Time- 1 week delay, Cost- Rs 14 Lacs
Risk cost= 14 Lacs x 0.25= 3.5 Lacs
Risk Time= 1 week x 0.25= 0.25 Week

12. Post Risk Analysis-
1. Volume losses due to water ingress from the joint locations
2. Under cut/ Over cut while grabbing of D-Wall Panels
3. Honey comb formation due to underwater concreting
4. Chances of soil collapse while concreting affecting quality of concrete
5. Improper fixing of Water bars at joints
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Cavity formation at base level of P101 and 102
Impact-
1) Sink hole formation on road
2) Dangerous occurrence
3) Ingress of water and slush inside station
Immediate risk response-
Traffic diversion
Backfilling near affected area
Sink hole filled with concrete
40mm Plate laid over top surface of road

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Risk factor-
Likelihood- 0.25
Potential impact- Time- 4 week delay, Cost- Rs 44 Lacs
Risk cost= 44 Lacs x 0.25= 11 Lacs
Risk Time= 4 weeks x 0.25= 1 Week
Mitigation-
1. Installation of bore-well adjacent to the affected D-Walls
2. Lowering the water table with the help of installed bore wells
3. Excavating inside the station box near the affected panel up to a depth of 1m
4. Steel plate fixing at the affected location
5. Micro-concrete grout in the affected panels.
Action taken-
1. Contiguous pile
2. Provision of grouting column around the Contiguous pile

14. Risk Assessment Matrix
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15. Innovations in Method of Constructions
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Utility Diversion
Inter displacement and interchange of Utility diversion Methodology to expedite
Diaphragm wall Construction for streamlining with the planned programme.
Training of one team to take off the diversion works internally to reduce the contractor
dependency risk
Provision of a new opening at Roof for carrying excavation without struts
Elimination of struts at Base level by modified design for D-Walls
By making bund over the guide wall
Keeping the poly-mud level always higher than the ground water level
Installation of bore-well adjacent to the affected D-Walls and lowering water table to
reduce the ingress of water and micro-concrete at 1m at intervals as a control measure to
avoid the risk of sink hole
Excavation Sequence
Soil Collapse in D-Walls
D-Wall Cavity formation

16. Conclusion and Learnings:-
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