GB2303394A - Tunnelling methods - Google Patents
Tunnelling methods Download PDFInfo
- Publication number
- GB2303394A GB2303394A GB9615098A GB9615098A GB2303394A GB 2303394 A GB2303394 A GB 2303394A GB 9615098 A GB9615098 A GB 9615098A GB 9615098 A GB9615098 A GB 9615098A GB 2303394 A GB2303394 A GB 2303394A
- Authority
- GB
- United Kingdom
- Prior art keywords
- tunnel
- lining
- concrete
- sprayed concrete
- excavation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000000034 method Methods 0.000 title claims description 27
- 239000011378 shotcrete Substances 0.000 claims description 15
- 238000009412 basement excavation Methods 0.000 claims description 14
- 239000004567 concrete Substances 0.000 claims description 8
- 229910000831 Steel Inorganic materials 0.000 claims description 5
- 239000010959 steel Substances 0.000 claims description 5
- 238000005507 spraying Methods 0.000 claims description 2
- 238000010276 construction Methods 0.000 description 6
- 238000012360 testing method Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 239000004927 clay Substances 0.000 description 2
- 238000009415 formwork Methods 0.000 description 2
- 239000012634 fragment Substances 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 239000011435 rock Substances 0.000 description 2
- 238000009416 shuttering Methods 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 238000003491 array Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000007586 pull-out test Methods 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 238000012163 sequencing technique Methods 0.000 description 1
- 229910021487 silica fume Inorganic materials 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
- E21D11/105—Transport or application of concrete specially adapted for the lining of tunnels or galleries ; Backfilling the space between main building element and the surrounding rock, e.g. with concrete
Landscapes
- Engineering & Computer Science (AREA)
- Structural Engineering (AREA)
- Architecture (AREA)
- Mining & Mineral Resources (AREA)
- Civil Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Lining And Supports For Tunnels (AREA)
Description
TUNNELLING METHODS
The present invention relates to tunnelling methods and tunnelling structures.
The known New Austrian Tunnelling Method (NATM) involves the sequential installation of a tunnel lining following staged excavation. The lining may be of sprayed concrete, but if so it is considered as totally sacrificial.
If a primary permanent lining is constructed, the primary lining is subsequently further lined with shuttered insitu concrete and does not contribute to the structural lining of the tunnel.
The present invention provides a method of constructing a tunnel, comprising the steps of excavating the tunnel and then lining the tunnel with a permanent supporting structural shell of sprayed concrete by spraying the concrete as a closed ring, including the invert part of the tunnel.
Preferably, the lining is installed sequentially as excavation proceeds, the ring being closed at a distance of not more than 3 tunnel diameters from the face.
In an embodiment of the invention, the method further comprises the step of applying a secondary lining of sprayed concrete over the inner surface of the said permanent supporting structural shell, the secondary lining, including the invert part, being constructed as a closed ring. The resulting sprayed concrete shell may thus comprise a single or multi-layered system.
The method of the invention may involve excavation sequence and advance profiles such as Crown, Bench and
Invert and Side Wall Drift. Profile selection is based on upon the consideration of a number of factors, as such: stability of the prevailing ground conditions; need to limit surface and subsurface deformations induced by the tunnelling works; cross sectional area and geometry of the tunnel face; and length of tunnel to be driven.
Excavation is performed in a controlled manner using mechanical excavation equipment and/or manual excavation with hand tools. Excavated spoil removal can be by rail, by loading shovel, by conveyor belt or any combination thereof.
The concrete lining is applied using pneumatic wet or dry sprayed concrete methods. The primary and/or secondary lining can either be totally unreinforced, reinforced with steel reinforcing bars or mesh or with steel fibres.
Materials, specifications and workmanship standards are chosen so as to be consistent with the required design life for the tunnel. All materials should therefore be stable, durable and of sufficient strength to meet design life requirements. Where necessary, the inner surface of the tunnel lining can be finished by hand to provide a surface finish equivalent to a formed concrete surface.
Compared to known tunnelling methods, the invention is advatagous since it enables maximum economy of materials and construction effort. For instance, it does not require expensive and cumbersome shuttering systems to form the permanent lining, and complex tunnel geometries, particularly at tunnel intersections and the like, can be formed without the need for purpose built formwork systems.
Indeed, there is no requirement for any shuttering, formwork or falsework, as the tunnel lining is formed entirely using sprayed concrete techniques. Furthermore, the primary lining is considered as at least part (typically at least 50t) of the permanent tunnel lining, there being no requirement for a cast-in-place secondary lining.
In order that the present invention may be more readily understood, reference will now be made, by way of example only, to the accompanying drawings, in which:
Figure 1 shows a longitudinal section through a tunnel in the process of excavation according to an embodiment of the invention;
Figure 2 shows a transverse section through the tunnel shown in Figure 1;
Figure 2A shows an enlarged fragment of the cross section of Figure 2;
Figure 3 shows a longitudinal section through the tunnel of Figure 1 in its finished state;
Figure 4 shows a transverse section through the tunnel shown in Figure 3; and
Figure 4A shows an enlarged fragment of the cross section of Figure 4.
Figures 1 and 2 show the excavation of a tunnel through clay 1 or the like at an excavation face 2. As excavation progresses, the tunnel is lined with a sprayed concrete layer 3. The sprayed concrete shell forms a closed ring, including the invert 4, as far as point X which is at a distance of not more than 3D from the face 2, where D is the diameter of the tunnel. A detail of this permanent primary lining 3 is shown in Figure 2A.
Figures 3, 4 and 4A show the finished tunnel which incorporates a secondary lining 5, also of sprayed concrete and also constructed as a closed ring.
The following description of a trial of a method according to the invention should be taken as constituting an illustrative example only, and is not intended to limit the scope of the invention.
Wet sprayed concrete was used to generate the complex profile of a 6.5 m ID enlargement and 4.5 m ID spur at 450 to a main 1.4 km drive, the junction being located beneath an aircraft stand at a busy international airport. The aircraft stand was utilised by aircraft weighing over 350 tonnes each, and additionally, the excavation was carried out close to terminal buildings and subsurface aviation fuel lines, making the consideration of ground movements relating to the works of utmost importance. Convergence and settlement within the tunnel and at the surface during and following construction were demonstrated to be well within the contract specification and below the limits which would have been expected usIng traditional techniques. Face loss expressed as a percentage of face area averaged 0.5.
The machIne used for the excavation was track mounted and equipped with a swivel boom to enable accurate cutting of the tunnel profile, and was electrically driven, thus precluding possible atmospheric pollution caused by diesel engined plant.
The primary tunnel lining, consisting of micro-silica sprayed concrete, was designed to withstand the full overburden loads anticipated. When using dry-spray techniques this primary lining is generally ignored in the permanent works design, whereas in our system and wet spray techniques the benefit of the primary lining was exploited thus allowing obvious savings. "On the wall" strength was determined by extensive coring, and averaged 60N for the base mix and 45N where accelerator was used. The concrete density was found to be very good with a typical permeability of 1 x lO~:imx'sec being achieved.
The project quality plan, conforming to ISO 9000 requirements, included for example a concrete testing programme devised to control early high 'on wall' strength based on Hilti pull-out tests and extensive core testing.
Extensive pre-works trials including permeability testing were performed on test panels and a full size tunnel mockup.
The setting out of the profile and sequencing of the works on the junction was carried out under the direct supervision of NATM engineers at the face, decisions being made based on observation of the ground and concrete performance and on monitored data. The monitoring regime included observations of in-tunnel settlement and convergence, surface and sub-surface levelling arrays together with bore hole inclinometers and extensometers to monitor movements at the tunnel horizon. Surface settlements averaged some 3 mm, mostly reflecting the movement of aircraft and tugs on and off the stands, whIle in-tunnel settlement and convergence averaged 5 mm.
The shafts, 6 in total, were generally 10.3 m ID and were sunk into underlying clay through the overlying, water bearing gravels using conventIonal caisson jacking techniques. Thereafter the construction involved excavation at night followed by the application of a steel fibre reinforced sprayed concrete lining on dayshift. Tunnel portals were constructed in sprayed concrete as the shaft sinking proceeded in order to avoid a later requirement for extensive temporary works.
In tunnel, surface and subsurface deforma-~on monitoring should be performed at regular intervals to ensure that tunnel lining behaviour is performing as expected. Where unexpected deformation trends or levels are detected, the method allows for the installatlon of further support to stabilise linIng movements. Sufficent tolerances are therefore built into the preliminary design so that additional stabillsing layers (deemed necessary by
Inspection of tunnel deformation data) can be applied without encroaching on the minimum internal dimensions for the works.
The present tunnel construction method is suitable, for example, for highways tunnels, railway tunnels, rapid transit tunnels, aqueducts and sewers, underground caverns, shafts, and special tunnels to carry pipes, cables or other services.
The method is suitable for the construction of tunnels of cross sectional area greater than three metres square. No upper bound cross sectional area is specified.
The method is applicable to the construction of tunnels in both soft (non rock) and rock strata, both above and below the water table.
In summary, it will be appreciated that the invention provides a low cost and quick alternative to traditional
NATM methods.
Claims (6)
1. A method of constructing a tunnel, comprising the steps of excavating the tunnel and then lining the tunnel with a permanent supporting structural shell of sprayed concrete by spraying the concrete as a closed ring, including the invert part of the tunnel.
2. A method according to claim 1, wherein the lining is installed sequentially as excavation proceeds, the ring being closed at a distance of not more than 3 tunnel diameters from the face.
3. A method according to claim 1 or claim 2, wherein the method further comprises the step of applying secondary lining of sprayed concrete over the inner surface of the said permanent supporting structural shell, the secondary lining, including the invert part, being constructed as a closed ring.
4. A method according to any preceding claim, wherein said permanent supporting structural shell and/or said secondary lining is reinforced with steel bars, mesh or steel fibres.
5. A method of constructing a tunnel substantially as described herein With reference to the accompanying drawings.
6. A tunnel constructed according to the method as claImed in any of the preceding claims.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GBGB9514734.4A GB9514734D0 (en) | 1995-07-19 | 1995-07-19 | Tunnelling Methods |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9615098D0 GB9615098D0 (en) | 1996-09-04 |
| GB2303394A true GB2303394A (en) | 1997-02-19 |
Family
ID=10777885
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GBGB9514734.4A Pending GB9514734D0 (en) | 1995-07-19 | 1995-07-19 | Tunnelling Methods |
| GB9615098A Withdrawn GB2303394A (en) | 1995-07-19 | 1996-07-18 | Tunnelling methods |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GBGB9514734.4A Pending GB9514734D0 (en) | 1995-07-19 | 1995-07-19 | Tunnelling Methods |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB9514734D0 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100516464C (en) * | 2006-06-02 | 2009-07-22 | 四川省交通厅公路规划勘察设计研究院 | Tunnel support structure |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1396770A (en) * | 1971-09-29 | 1975-06-04 | Bernold J | Tunnel boring |
| WO1985004214A1 (en) * | 1984-03-13 | 1985-09-26 | Neste Oy | Lined rock cistern or tunnel |
-
1995
- 1995-07-19 GB GBGB9514734.4A patent/GB9514734D0/en active Pending
-
1996
- 1996-07-18 GB GB9615098A patent/GB2303394A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1396770A (en) * | 1971-09-29 | 1975-06-04 | Bernold J | Tunnel boring |
| WO1985004214A1 (en) * | 1984-03-13 | 1985-09-26 | Neste Oy | Lined rock cistern or tunnel |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100516464C (en) * | 2006-06-02 | 2009-07-22 | 四川省交通厅公路规划勘察设计研究院 | Tunnel support structure |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9615098D0 (en) | 1996-09-04 |
| GB9514734D0 (en) | 1995-09-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |