Foreseen Challenges In Underground Tunneling For Mumbai Metro Line 3. S.K.GUPTA Director (Projects)/MMRCL

Transcription

1 Foreseen Challenges In Underground Tunneling For Mumbai Metro Line 3 S.K.GUPTA Director (Projects)/MMRCL

2 CONTENTS OF PRESENTATION Project Route Project Overview Challenges MML 3 Geology, Mumbai Technical challenges NATM TBMs selection Building Condition Monitoring Quality Assurance

3 PROJECT ROUTE

4 PROJECT ROUTE Fully Underground Length: 33.5 Km Stations: 27 (26 U/G + 1) Completion Cost: US$ 3.5 Billion Phase 1: SEEPZ to BKC- June 2021 Phase 2: BKC to Cuffe Parade- Dec Ridership 1.22 Million 1.70 Million Headway (CP-BKC) 4 min, 16sec 2 min, 55 sec 256 sec 175 sec Coaches 248 (31 x 8 cars) 336 (42 x 8 cars)

5 PROJECT OVERVIEW

6 PROJECT OVERVIEW(CIVIL WORKS) Contract Packages Civil Works Packag e No. Limits Length (K.M.) 1 Cuffe Parade to CST CST to Mumbai Central Mumbai Central to Worli Worli to Dharavi 6.08 Stations Cut & Cover Cuffe Parade, Vidhan Bhavan, Churchgate C.S.T. Mumbai Central, Mahalakshami, Science Museum, Acharya Atre Chowk, Worli Siddhi Vinayak, Dadar NATM Hutatma Chowk Kalbadevi, Girgaoan, Grant Road - Shitaladevi 5 Dharavi to Santacruz Santacruz to CSIA (International) 4.45 CSIA (International) to SEEPZ Total Length of the Corridor 33.5 Dharavi, B.K.C., VidyaNagari Santa Cruz CSIA Domestic, Sahar Road, CSIA International Airport - MIDC, SEEPZ Marol Naka

7 CHALLENGES The Mumbai city will see such a big scale infrastructure intervention, spanning 33.5 km in the city for the first time in recent history. The project poses number of challenges: Administrative Geological Technical Logistics etc. I will cover only the Geological and Technical Challenge(Topographical and QA related)

8 Mumbai Geology Reclamation History of Mumbai City

9 TOWARDS SEEPZ PAREL MAZGAON B.K.C. LITTLE COLABA GIRGAON CUFFE PARADE DADAR RECLAIMED LAND MUMBAI CENTRAL CHURCHGATE MAHIM WORLI BOMBAY Mumbai Geology, Historical Background 9 COLABA

10 Mumbai Geology Mumbai : Seven islands with history of reclamation since 1800 Deccan trap formation 65 Ma ago Parent rocks of Mumbai region are volcanic in nature Basalt, Breccia, Tuff Intertrappean Sedimentary Rocks like Shale (long period of quiescence in volcanic activity) Thickness of overburden soil 1.0 m to 14.0 m. Predominantly: Marine Clay, boulders, filled-up material Ground Water is close to ground level

11 MML 3 GEOLOGY, MUMBAI Anticipated Construction Challenges Geological Condition Compact Basalt Contact Boundary between Basalt and Breccia Tuff, Tuff Breccia Intertrappean Shale Possible Construction Issues High degree of jointing, water bearing strata, rock fall, instability Filling of clay at contact plane, weak rock mass at contact zone Clay minerals in rocks produce sticky muck and may jam cutters affecting progress Unstable due to their inherent softness which may be aggravated by their closely spaced laminations, water seepage along bedding planes, rock fall due to softening in contact with water, swelling behaviour

12 MML 3 GEOLOGY, MUMBAI Varying Geological Conditions Ground Water Table 18.6 m STATION Shale, Breccia, Basalt Grade IV, V Basalt Grade I, II TUNNEL

13 Challenges in TBM Tunnelling - Varying Geological Conditions

14 TECHNICAL CHALLANGES

15 Technical The corridor passes through densely populated and congested parts of Mumbai It is practically unavoidable not to have tunnels passing directly underneath or in a close proximity of existing buildings and existing infrastructure. The alignment is in proximity of : High Rise Buildings (existing) Proposed Development / Redevelopment Heritage Buildings Dilapidated Buildings Flyovers and Metro Viaduct Railway Lines Most of the Stations are on road and very close to buildings There is limited space for planning and implementing: Traffic Diversion Utility Diversion

16 Heritage Buildings HUTATMA CHOWK STATION Arrangement for Cut & Cover Box with One NATM Platform Tunnel outside the Box

17 HUTATMA CHOWK STATION HERITAGE PRECINCT 19

18 Dilapidated Buildings TBM Tunnel s GIRGAON Girgaon

19 Crossing Railway Lines & Water Bodies Stabling Sidings & Cross- Passages by NATM Tunnel Crown 19.0 m below water level Tunnel Crown 15 m below Suburban Railway Tracks

20 Tunnels under Flyovers A CSIA International A Variation in rock head SECTION A-A Foundation Details of Sahar Elevated Road based on actual piling records

21 Tunnels in Proximity of High Rise Buildings 70 m ROCK LEVEL 25 m 4.7 m 2.8 m 4.9 m

22 New Austrian Tunneling Method (NATM)

23 NATM TUNNELING New Austrian Tunneling Method (NATM) is being employed extensively in stations to excavate where ground access is not available. Seven stations out of 26 have a component of NATM in 4 structural forms Reversal siding at Cuffe Parade as well as siding at BKC below a large water body are to be done by NATM NATM requires less land, and are chosen based on the type of locality /land availability/geology Cross-Overs proposed at CST and Sahar Road All Cross passages are by NATM

24 Contract Packages NATM Work Scope Package No. UGC-01 UGC-02 Limits Cuffe Parade to CST CST to Mumbai Central NATM Work Scope Turn back/stabling siding tunnels at Cuffe Parade, Hutatma Chowk station Cross Passages Kalbadevi station Girgaoan station Grant Road station Cross Passages UGC-03 Mumbai Central to Worli Cross Passages UGC-04 UGC-05 Worli to Dharavi Dharavi to Santacruz Shitaladevi station Cross Passages Santacruz station Two stabling siding tunnels at BKC Cross Passages UGC-06 Santacruz to CSIA (International) Cross Passages UGC-07 CSIA (International) to SEEPZ Marol Naka station Cross Passages

25 NATM TUNNELING

26 KALBADEVI -CROSS SECTION Cross Section at Cut & Cover Box Cross Section at NATM

27 TBM For Mumbai Metro Line 3

28 TBM Design Approval Process - Introduction Design Challenges Complexity of Geology and Hydrogeological conditions Heritage, religious, high rise and dilapidated building Extremely congested city Fast Track Project Approval Process TBM selection by contractors Standardised Design Approval process o Integrated approach to design approval o Re-iterative design review process as more geotechnical data became available o Collaborative debates and discussions TBM by Category TBM by Contractor and Supplier

29 TBM Design Requirements Following TBM design approval parameters were established during Kick-off meetings Initial TBM design was based on Tender Geotechnical Data, GIR & GFR Geometric parameters o Alignment, excavation diameter, segmental lining preliminary design, minimum radius of curvature etc. Geotechnical and hydrogeological parameters o Rock Types and Class, water table, permeability, cohesion etc. Mechanical requirements of the TBM o Thrust pressure, torque, cutter head design (Particularly on Used TBM), main bearing loads, thrust pad and annular grouting requirements Other TBM Design Requirements o Transportation through congested and constrained road network o Geo-statical, dead loads, and erection loads

30 TBM TYPES SELECTED DUAL MODE HARD ROCK TBM ROCK EPB TBM

31 Building Condition

32 Principle Control Process to Protect the Existing Heritage Buildings and Adjacent Structure MML3 Project has established a very stringent process in design and construction stages to safeguard and protect existing heritage buildings, weak buildings and adjacent structures with respect to structures integrity and safety. The control process broadly consists of four(4) stages: 1. Assessment of existing building condition and assigning allowable impact limit categories. 2. Design the station and tunnelling excavation method impacts to be within limits of the adjacent buildings categories 3. Design and installation of protection and mitigation measures where necessary. 4. Close and continuous monitoring duration construction and revising designs as per steps 2 and 3

33 Keeping watch on and getting early warning of any excessive and undue movement and/or distortion of adjacent ground and buildings is the underlined principle of the monitoring philosophy. Instrumentations are installed on the buildings and ground before commencement of work to monitor vital parameters of the building and ground during Construction: Settlements Tilting Distortions Ground water level Stress and displacement in excavation and support system Vibrations

34 Monitoring Mumbai Metro Line 3

35 Monitoring and TBM Active Control Control System Controlling of Boring Process: guide parameters from interdisciplinary processing of geotechnical, geodetic and machine data

36 QUALITY ASSURANCE

37 Quality Assurance General Quality Assurance of MML3 is implemented on a well structured state-of-art System, monitored and recorded to ensure 120 years Infrastructure Design Life. Mainstays for assuring quality: Contract Documents ISO, BIS,DIN, EN Project Quality Plan Design Quality Plan Manufacturer Quality Plan Approved Design and Drawings Approved Method Statements & ITPs Instruments used for ensuring quality: Routine Audits & Construction Monitoring Approval Process Assessment Process Request for Inspection (RFIs) Contractor s Surveillance Inspections Non Conformance Report (NCRs) Corrective Action Report (CARs)

38 Conclusion

39 Conclusion Dealing with advance geology within an urban environment, similar to Mumbai, can be problematic, leading to significant tunnelling delays if not foreseen. In variable ground conditions this can prove demanding depending on Stress State, Rock Competence and Groundwater inflows. Mitigating delays associated with bad ground at significant depth requires foresight, comprehensive design solutions and advance planning. Tunnelling operations has commenced with 8 TBMs with all TBMs performing satisfactorily.

40 General Consultants

41 Thank you