Documents pédagogiques internes au Mastère TOS. Tunnel Boring Machines (TBM) an introduction. Conventional and TBM Tunnelling

Transcription

1 Tunnel Boring s (TBM) an introduction Professor Jian ZHAO EPFL ENAC LMR 1 Conventional and TBM TBM and Use of TBM in Switzerland Conventional Volume Length D&B 2 TBM TBM D&B 3 1

2 Boom Excavator Rock TBM Non- for weak weathered rock and firm with Soil TBM Mixed ground conditions of rock and Ground from competent rock to Basic Functions 1. Excavation of the ground Partial Face excavation 2. Support the ground Full Face excavation 4 5 Basic Functions 6 2

3 Basic Functions 3. Mucking of Excavated Materials 7 Advantages and Risks ADVANTAGES Enhanced health and safety conditions for the workers. Industrialization of the tunnelling process, with ensuing reductions in cost and construction times. Possibility of crossing complex geological and hydrogeological conditions safely and economically. Good quality of finished product (surrounding ground less altered, precast segment lining). Boom Excavator Non- RISKS Lack of flexibility: Once the technique has been chosen it is virtually impossible to change it throughout the construction of the tunnel. Therefore, a correct analysis of different parameters is needed for the choice of the correct mechanized tunnelling technique 8 for weak weathered rock and firm with Mixed ground conditions of rock and Ground from competent rock to 9 3

4 s and Mobile Excavators Rock excavation machine for moderate rock strength (up to 120 MPa), consisting of: Cutterhead Extension arm or boom Muck conveyor Crawler chassis Loading apron 10 s and Mobile Excavators Continuous Mining ADVANTAGES Flexibility. Possibility of excavating tunnels of different sizes and shapes. Low capital investment. No installation time needed. Relatively short time from order to delivery at the site. s LIMITATIONS Mobile Miner 11 No protection or support given to the rock while excavating. Limited to stable ground. Suitable to excavate rocks of UCS up to 120 MPa. Excavation coverage is limited by the size of the machine. 12 4

5 Boom Excavator Non- for weak weathered rock and firm with Mixed ground conditions of rock and Ground from competent rock to 13 Tunnel and Enlarge s boring machine bores the final section from an axial pilot tunnel from which it pulls itself forward by means of a gripper unit. 14 Tunnel Bore Extender (TBE) used at Uetliberg Tunnel in Switzerland. Tunnel is enlarged from a 5 m pilot tunnel to 14.4 m. 15 5

6 Boom Excavator Non- for weak weathered rock and firm with Mixed ground conditions of rock and Ground from competent rock to Rock excavation machine for competent and hard rocks. Movement of machine uses the grippers. Double gripper TBM Gripper Rock is fragmented by chipping between cutters. 18 6

7 Single gripper TBM MOVIE ADVANTAGES Rapid excavation rate in hard rocks. Capable to excavate hard rocks of UCS up to 300 MPa. For tunnels of diameter up to 14 m. Flexible rock support measure according to ground conditions. Boom Excavator Non- Double gripper TBM LIMITATIONS 19 No protection or support given to the rock while excavating. Limited to stable ground. Gripper may have difficult in poor rock masses with low strength. Dedusting is needed. 20 for weak weathered rock and firm with Mixed ground conditions of rock and Ground from competent rock to 21 7

8 and TBM Boom Excavator Non- Platform 22 for weak weathered rock and firm with Mixed ground conditions of rock and Ground from competent rock to TBM with 23 Open face TBM can be for rock and firm without the need of face pressure. 24 8

9 TBM with Flood doors closed It usually does not have a chamber to provide pressure support to the excavation face. Excavated materials can be transported directly from the cutterhead. However, it can often to be combined with pressurised TBM but to operate without pressure (open mode). Flood doors open Boom Excavator Non- 25 for weak weathered rock and firm with Mixed ground conditions of rock and Ground from competent rock to 26 When open face shield excavating -bearing, water penetration can be prevented by having the shield and a section of the tunnel protected by a lock system using compressed air. The required pressure is monitored continuously and adjusted automatically where necessary by a compressed air system consisting of two control circuits. 27 9

10 Boom Excavator Non- for weak weathered rock and firm with Mixed ground conditions of rock and Ground from competent rock to The largest slurry shield φ15.43m (2006), used for Shanghai Changjiang Under River Tunnel Project TBM excavation face is supported by pressurizing bentonite in cutterhead chamber. Circulation of the fluid flushes out the muck. Pressure is maintained by controlling discharge rates. 1. Cutting wheel 2. Air bubble 3. Bentonite suspension 4. Drive unit 5. Stone crusher 6. Push cylinder 7. Air lock 8. Steer cylinder/ shield tail 9. Segment erector 10. Segment conveyor MOVIE 30 10

11 ADVANTAGES Equal distribution of pressures against mixed-face conditions. Good performance in sands and gravels. Gives better face stability (formation of mud-cake). Allows access to the face with compressed air. Boom Excavator Non- LIMITATIONS Need of large separation plants for bentonite separation and treatment. Not suitable for clayey-silty grounds. 31 for weak weathered rock and firm with Mixed ground conditions of rock and Ground from competent rock to 32 The largest EPB machine φ15.2 m (2006) for Madrid M-30 project

12 TBM excavation face is supported by pressurizing earth inside the cutterhead chamber. Earth pressure in the chamber is regulated by the rate of earth discharge through the screw conveyer. ADVANTAGES Very well adapted for excavating silty and clayey grounds. No need of separation plant. The use of additives (foams) enables EPB s to be used with sandy-gravely s. MOVIE Foams and chemical additives are used to conditioning for better control of pressure and muck discharge, in sandy grounds. LIMITATIONS Irregular distribution of pressure against mixed face conditions. Problems when boulders are encountered: no possibility of fitting a rock crusher. Wearing of the screw can lead to bad pressure distribution. More difficult access to the face than for slurry shields (no mud-cake is formed)

13 Selection of Boring Based on Soil Grain Size Distribution EPB Slurry Boom Excavator Non- EPB Selection of Boring Increase of EPB Use in Gravelly Grounds Slurry 37 EPB used Chengdu Metro 38 for weak weathered rock and firm with Mixed ground conditions of rock and Ground from competent rock to 39 13

14 The cutterhead has combined features for hard rock and excavation. It enables the shield TBM to excavate through both rocks and s, and rock- mixed face. Mix-shield can be EPB or slurry based. ADVANTAGES Flexible in excavation of rock,, and mixed ground. Face pressure features are maintained by either EPB or slurry. Other advantages of EPB or slurry shields. Boom Excavator Non- Slurry LIMITATIONS EPB 40 Maintaining face pressure may be difficult, particularly for EPB based machine. Cutter wear and damage is generally high. Muck discharge may be difficult due to mixing of rock and. Other limitations of EPB or slurry shields. 41 for weak weathered rock and firm with Mixed ground conditions of rock and Ground from competent rock to 42 14

15 It combines the features of gripper and shield in a TBM, and enables fast excavation even in varying rock formations. Gripper 43 In poor ground condition, it works as a single shield machine. When in rocks, grippers are used for forward movement, so segment can be simultaneously installed while excavating. ADVANTAGES Good flexibility for varying grounds. High advancement rates. The increase depends on operation. Possibility to have different support measures, e.g., segmental lining, and bolts-sc. Possibility of ground treatment and/or probing through the gap between shields. MOVIE LIMITATIONS 44 Maintenance problems of articulation between the shields. Long shield length: possible drawback for squeezing grounds. More expensive than conventional shields

16 Boom Excavator Non- for weak weathered rock and firm with Mixed ground conditions of rock and Ground from competent rock to 46 It is a machine has both EPB and slurry system installed. It can convert between EPB mode and slurry mode, to cope with grounds suitable for both type of machines. Slurry Mode EPB Mode 47 Open Mode EPB Slurry EPB 48 16

17 Boom Excavator for weak weathered rock and firm Steel set, bolt, SC, CC Bolt, SC Non- Bolt, SC Bolt, SC C segments C segments with C segments Mixed ground conditions of rock and Ground from competent rock to New TBM Technologies Optimizing underground space C segments C segments C segments C segments, bolt, SC C segments New TBM Technologies Optimizing advancement 51 17

18 New TBM Technologies Optimizing machine with variable ground condition Boom Excavator Non- 52 New TBM Technologies Under Water TIMBY 53 Ground Condition Support Impact breaker, ripper, pick, and bucket for weak rock and Steel set, bolt, sprayed concrete, cast-in concrete Bolt, sprayed concrete, cast-in concrete, steel set Rock mixed with with Concrete segmental lining Rock mixed with Rock mixed with Varying from rock to Mixed ground of rock and Varying s from sands to clays Segmental lining, bolt, sprayed concrete Concrete segmental lining 54 18