Informe sobre el método NATM

NO	DATE	LOCATION	REMARKS AND LITERATURE REFERENCES	REPORTED CAUSE	NATURE OF REFERENCE OR SOURCE OF INFORMATION	BRIEF CIRCUMSTANCES	PROJ.	URBAN OR RURAL	CONSEQ. OTHER THAN ADDITIONAL PROJECT COST AND TIME
1	October 1993	Rail tunnel. Paris, France	Collapse Müller 1978	A6 A8	Published article 1978	Example of 'numerical' errors in that convergence measurements no processed and acted upon. (Reference to Massenberg Tunnel). Consequence unknown. No indication if urban environment.	Rail	?	?
2	18 December 1981	Sao Paulo metro. North-South link Brazil	Sudden serious instability during construction. Noise and lining cracking Kochen et al 1987	A1	Conference paper presented in Paris 1987	No collapse but cone of settlement at surface buildings (urban area) max value of 120 mm. 6 m dia; 200 mm shotcrete lining with 8 m overburden. Change of ground conditions within face and change from drained to undrained conditions are likely to have affected stability, timer propping introduced to prevent full collapse.	Urban metro	Urban	Buildings demolition
3	1983	Santana Underground Railway, Brazil	Cave-in	Insufficient detail available	Private correspondence	First use of NATM in Brazil. No casualties, but collapse progressed to street level where cave-in depth was 80 cm. residential suburb.	Rail	Urban	6 Houses demolished
4	13 November 1984	Landrücken Tunnel, Germany	Collapse Nussbergen & Judtmann 1987 John, Wogin & Heissel 1987 [Fig. 7]	A8, A10	a) Published article 1987 b) Conference Paper 1987	11 Km tunnel through various caving-in erosion ground features of tubular or chimney like forms. Total of 47 such zones encountered. First point of failure was shearing of the base of the crown and walls due to overload-rest of collapse sequences shown on diagrams. Consequence unknown but delays due to recovery operations made up in the end.	Rail	Rural
5	1984	Bochum Metro Germany #1	Collapse Laue and Sager 1987	B1, A7, A9	Conference Paper 1987	Daylight collapse 7.5m cover, 150 mm lining 30 minutes. Ground movement involved 300 cu.m in urban/street area, Collapse put down redistribution of load from front excavation. Crown advance shortened afterwards.	Rail	Rural	Urban disruption
6	17 January 1985	Richthof Tunnel, Germany	Collapse Engels and Aubel 1987	A1	Conference paper 1987	Crows and bench drill and blast rock. 20m overburden in rural area. Tunnel collapse 18 m with surface crater 11 m by max of 6 m deep. 3 moths to re-excavate.	Rail	Rural
7	1985	Bochum Metro, Germany #2	Collapse Laue and Sager 1987	A1	Conference paper 1987	Daylight collapse to street level. Fissuring and water blamed for ground instability at the face. cavity of 30 m3 formed under road as a result of ground collapse into tunnel.	Metro	Urban	Urban disruption
8	August 1985	Kaiserau tunnel, Germany	Collapse Wallis 1990 (1988)	A4, A5	Published article 1988 &1990	"Almost daylight" collapse. 100m in from potal, full heading and bench under 25 m cover. "Collapse occurred during excavation of the beach". No further details. No indication of consequences except change in excavation sequence to include two side drifts. 4 months delay.	Rail	Rural
9	17 February 1986	Krieberg Tunnel, Germany	Collapse Wallis 1987 (1900) Leichnitz & Schlitt 1987 [Fig. 8]	A3, A10	a) Published article 1987 &1990 b) Conference Paper 1987	3 km tunnel through sandstone. Tunnel with two side drifts and top crown section. Collapse of partially completed lining adjacent to the face thought to be due to local overstressing due to sand lenses and water. Progressive collapse of crown and 2 drift tunnels backwards for 55m. Very substantial surface-damage in rural area. Collapse within 30 minutes.	Rail	Rural	Large surface damage (rural)
10	Before 1987	Munich Metro, Germany #1	Collapse Weber 1987 [Fig. 9]	C2	Published article 1987	Tunnel collapse and inundation and flooding of shaft. Competent cover immediately outside the shaft was not 1.5 m as planned but inadequate 80 cm and upper waterlogged strata broke though. Full collapse to surface-movement of 450 m3 involved.	Metro	Urban	Urban disruption excavator buried
11	Before 1987	Munich Metro, Germany #2	Collapse Weber 1987 [Fig. 10]	A1, A12	Published article 1987	Cave-in to surface- 5 m overburden. 30 m3 of gravel. Collapse in part due to omission of distance spacers between crown arches. Crown excavation underway. Water level below tunnel.	Metro	Urban	Urban Disruption
12	Before 1987	Munich Metro, Germany #3	Collapse Weber 1987 Kovari and Weber 1991 [Fig. 11]	A1	a) Published article 1987 b) Conference Paper 1991	300 m3 collapse to street surface as a result of local thinning of competent overburden (marl). Water level above tunnel. Face failure. Test boring vertically upwards behind the face at the first ring revealed adequate cover. Fore poling had just ended as it was thought no longer necessary. Excavator buried.	Metro	Urban	Urban disruption. Excavator buried.
13	Before 1987	Munich Metro, Germany #4	Collapse Weber 1987 Kovari & Weber 1991	A1, A12	a) Published article 1987 b) Conference Paper 1991	300m3 collapse to street surface as a result of local thinning of competent marl cover over the tunnel. Erosion feature encountered and water logged material flowed into the tunnel. Immediately prior there had been a danger zone including soffit lowering. Work was speeded up after this and test borings were not made which could have revealed the problem. Water level above tunnel.	Metro	Urban	Urban disruption
14	Before 1987	Munich Metro, Germany #5	Collapse Weber 1987 Kovari and Weber 1991 [Fig. 12]	A1, A12	a) Published article 1987 b) Conference Paper 1991	200 m3 collapse at street level. Local thinning of marl cover was anticipated and the waterlogged ground above was being treated by the formation of an arch of frozen ground. However due to poor construction there was an unintended gap of unfrozen ground through which the cave-in occurred.	Metro	Urban	Urban disruption. Excavator buried
15	Before 1987	Munich Metro, Germany #6	Material transfer Weber 1987 Kovari and Weber 1991	No collapse	a) Published article 1987 b) Conference Paper 1991	Very unusual tunnel to tunnel material transfer of 40 cu.m. One tunnel under 0.95 bar caused blowout into umpressurised tunnel 40 m away. Defective invert in secured tunnel. Loss of air to second tunnel put stability of first tunnel at risk and fears of settlement to station immediately above first tunnel. restoration of air pressure prevented to collapse/further damage.	Metro Urban	Urban
16	Before 1987	Weltkugel Tunnel, Germany	Cave-in Schrewe 1987	A3	Published article 1987	Cave in of 50 m3 while crown drainage underway. Sandstone (heavily weathered) described as "friable" destabilized to semi-stable and very brittle given the slightest mechanical effect. High convergence up to 245 mm but over 5 months period. Crown drainage ceased after cave-in but detailed circumstances not clear.	Rail	?
17	1987	Karawanken Tunnel, Austria/Slovenia	Large inflows and severe deformations. martin 1991	No collapse	Published article 1991	Hard rock tunnel with high tectonic stresses in Alps. Worst period has been with the high tectonic stresses combined with poorer quality rock. Maximum total convergence before stabilization has been 120 cm in places. tunnel, driven oversize to cope with severe squeezing. Shotcrete lining in crown cast into 5 segments with gaps in between to allow for closure. Also inrushes of methane. "Shotcrete and rockbolts serve mainly to rectify the ground deformations" says author.	7.5m dia Road Tunnel, 7.8Km long	Rural mountains
18	Before 1988	Kehrenberg Tunnel, Germany	Serious surface settlements. Propping installed to prevent tunnel collapse. Wallis 1988 (1990)	Not collapse 8A3)	Published article 1988 and 1990	Two photos of timber propping of distressed crown sections. Fault zone predicted but effect not fully appreciated. Water and sand overcome by dewatering and side drift construction. Length involved only 30 m. Consequence unknown apart from delays and additional cost.	?	Rail
19	1988	Michaels Tunnel, Germany	Collapse during pilot tunnel enlargement	(A10) Not enough details	Private correspondence	Collapse due to change in ground conditions which had been predicted to be a problem. It seems the support conditions for the strong rock were continued unmodified in the weaker ground. Lack of supervision and predictions party to blame. 11m span. Collapse during tunnel enlargement from pilot.	?	?
20	8 Jan 1989	Karawanken Tunnel, Austria/Slovenia	Collapse Maidl 1993	A1, A11	Published article 1993	Huge collapse involving 4000m3 in hard rock tunnel. Combination of very high water pressures (up to 36 bar) and loose broken rock in fault zone causing reduction in shear strength. Post Christmas break factor here and redistribution of stresses. Some suggestion that old records could have given warning.	Road	Rural
21	27 September 1991	Kwachon Tunnel, Korea	Collapse [Photo. 1]	Not enough information	Newspaper articles	Collapse of subway tunnel construction in soft ground described as "clay". 15 m overburden. Huge crater formed at the surface. Four workers trapped for 26 hours but rescued unhurt.	Metro	Rural
22	17 November 1991	Seoul Metro Phase 2#1 Korea	Collapse Park and Lee 1993	A1	Conference paper 1993 Newspaper reports	Daylight collapse up to ground surface which involved the embankment of a river. Roads collapse and gas main serving 5000 house holds was fractured. Ground described as "weathered rock or clay". 5 press cuttings. Crater 20 m x 15 m x 4m deep. Water from river into tunnel.	Metro	Urban	Fractured gas main
23	27 November 1991	Seoul Metro #2 Korea	Collapse affecting 3 buildings and utilities Park and Lee 1993 [Photo. 2]	A1	Conference Paper 1993 Newspaper reports	Substantial daylight collapse, 10 days after #1. Park and Lee describe as "sliding failure" rock movements along joint planes at the unsupported face. Street crater 28 m dias maximum. 3 buildings collapsed and communications, water, gas and sewerage broken. Incident subject to special 214 page report by Korea Civil Engineering Society. Newspaper report blames changing ground conditions and that bore holes were only taken at 100 m intervals. 28 m overburden,	Metro	Urban	Substantial urban disturbance
24	1992	Funagata Tunnel Yamagata Prefecture, Japan	Collapse	(C1)	Private correspondence	12 m wide 8m high 15 m overburden. Collapse due to water and loose ground-water due to rain and snow melt. Face of sand and gravel. Crater at ground level 6 m deep 4 m wide.	Road	Rural ?
25	12 February 1992	Seoul Metro Phase 2 #3, Korea	Collapse Park and Lee 1993	A2	Conference Paper 1993 Newspaper report	Daylight collapse. While excavating with road header soil and water and loose ground-water due to rain and snow melt. Face of sand and gravel. crater at ground level 6 m deep 4 m wide.	Metro	Urban	utilities broken, traffic problem
26	30 June 1992	Lambach tunnel, Austria	Collapse Vavrovsky and Schubert 1995	A5	Conference paper 1995	Daylight collapse. No dimensions and no indication of Urban or rural areas. Failure due to Urban or rural areas. Failure due to local weakness of bench-forewarnig of which had been given by differential movement of crown abutments one moth earlier. Failure of bench and ground above caused miners to be trapped in crown excavation some distance ahead. Rescued by	Rail	?
27	7 january 1993	Seoul Metro, Phase 2, Korea #4	Collapse Park and Lee 1993	A1	Conference Paper 1993 newspaper report	Daylight collapse to street level due to ground inflow (soft rock) combined with high ground water pressure. Face collapse. Photo of road crater-traffic suspended. Close to buildings.	Metro	Urban	Road distribution
28	2 february 1993	Seoul Metro, Phase 2, Korea #5	Collapse Park and Lee 1993	A1	Conference Paper 1993	Daylight collapse when "weathered rock" failed at face groundwater and material flowed in. 10 m wide eliptical shaped area subsided at river waterside 6 "heavy equipment's" buried.	Metro	Urban no buildings	Loss of construction plant
29	Feb/March 1993	Seoul Metro Phase 2, Korea #6	Collapse Park and Lee 1993	A3	Conference Paper 1993	Daylight collapse. Very little detail available. In weathered rock in the crown area involving rock movements along joint planes.	Metro	Likely urban
30	Feb/March 93	Seoul Metro Phase 2 Korea #7	Collapse Park and Lee 1993	A3	Conference Paper 1993	Daylight collapse. Very little detail available. In "residual clay" in the bench area where there was "shear failure".	Metro	Likely Urban
31	March 1993	Chungho Tunnel, Taipei, Taiwan	Collapse	A1	Private correspondence	15 m dia road tunnel under mountain. Collapse said to be caused of "bad ground conditions". Length of tunnel collapse involved 100m and collapse area took 2 years to repair. Other NATM collapses have occurred in Taiwan.	Road	Rural
32	November 1993	Road Tunnel at Avienda Santo Amaro, Sao Paulo, Brazil	Collapse [Photo. 3]	A1, A7 ,A3	Private correspondence, newspaper reports	Very low overburden in "fissured hard clay". Crown too far in advance reduced safety level and unstable convergence measurements resulted. Face collapse led to collapse of drain which filled tunnel with water which then piped over to other tunnel with sink hole between. Power supplies cut to 500.00 people. Massive urban disruption.	Metro	Urban	Huge urban disruption
33	1993	Road Tunnel ("poggio Fornello"), Tuscany, Central Italy	Severe deformations (?collapse) Pelizza et al 1994	A3	Conference paper 1994	Severe asymmetrical deformations of crown excavation due to poor geomechanical rock conditions. Excavated cross section 104 sq.m. Local propping installed to prevent full collapse. Excavation method changed to full section with 35-40 No. glass fibre grouted pipers installed in the face each up to 14 m long. Low overburden of 25 m max.	Road	? Rural
34	April 1994	Cardvalho Pinto Tunnel, Brazil	In-service remedial works, portal failure during construction	C1	Private correspondence Newspaper report	Only case discovered of in-service repairs to completed NATM tunnel. Cracks appeared and subsequent investigation discovered gaps between primary and secondary linings. Repairs involved removing areas of secondary lining and replacing it. Also portal failure during construction (date unknown).	Road	?	Traffic disruption
35	30 July 1994	Montemor Road Tunnel, Portugal #1	Collapse Wallis 1995	Nor clear (A3)	Published article 1995	Tunnel is twin bore, each 20 m wide for three traffic lanes. This collapse concerned the 6m high, 19.5 wide upper heading in the north tunnel with 20 m overburden. 45 m length of the tunnel collapse with a resulting 18 m dia. surface crater. Collapse was "sudden and unexpected". Precise collapse sequence unclear-said to have been influenced by a leaking small dia. water main above the tunnel construction.	Road	?	?
36	1 August 1994	Montemor Road Tunnel, Portugal #2	Collapse Wallis 1995	Not clear (A1)	Published article 1995	This collapse concerned pilot drive ( 6 drift total cross-section= of sound drive causing 5 m diameter surface crater. Precise collapse mechanism unclear. Likely to have been directly linked to collapse #1 26 hours earlier.	Road	Urban
37	August 1994	Galgenberg Tunnel, Austria	Collapse Schubert & Riedmuller 1995	A1	Technical Paper	Tunnel within heavily faulted area. Crown cross-section 60 m2; total cross-section 110m2. Lining incorporated "deformation slots" to cope with squeezing rock. Rock outburst from face occurred "suddenly" and with no early warning. Collapse volume estimates as 700 m3. Investigation did not uncover any construction defects.	?	? Rural	One death
38	20 September 1994	Munich Metro, Germany	Collapse 4 killed 27 injured Tiefbau 4/95 [Photo. 4]	A1	Published article 1995 and Newspaper reports	Metro construction in marl under waterlogged gravel's. cover to tunnel thought to be adequate but it thinned locally and its water and gravel's fell into tunnel. Bus traveling at street level fell into substantial crater which formed very quickly. One worker on surface and several bus passengers drowned. half face excavation at collapse.	Metro	Urban	Deaths. Urban disruption
39	21 October 1994	Heathrow Airport, London	Three tunnel collapse being investigated by the Health and Safety Executive

	CAUSE OF COLLAPSE	LOCATION	AUTHORS
	A-In the area of the NATM tunnel heading between the excavated face and the first completeres ring:
A1	Collapse of unstable natural ground at the excavated face	Sâo paulo 83, Richtof, Bochum #2 Munich #2, Munich #3, Munich #4, Munich #5, Karawanken, Seoul #1, Seoul #2, Funagata, Seoul #4, Seoul #5, Chungho, Sâo Paulo 93, Munich 94, Montemor #2, Galgenberg	Schrewe & Maidl (1987) Müller (1978) Leichnitz & Schrewe (1987) Kuhnhenn (1995)
A2	Collapse of the unstable excavated front face incorporating a man-made feature such as old borehole, well or culvert	Seoul #3
A3	Collapse of partly completed linning as a result of excessive settlement or convergence	Krieberg, Weltkugel, (Kehrenberg), Seoul #6, Seoul #7, Sâo paulo 93, Italy, Montemor #1	Leichnitz & Schrewe Kuhnhenn
A4	Collapse of the bench in the longitudinal direction	Kaiserau	Schrewe & Maidl Leichnitz & Schrewe
A5	Collapse of the bench during excavation in the direction to the centre of the tunnel	Kaiserau, Lambach	Schrewe & Maidl Leichnitz & Schrewe Kuhnhenn
A6	Longitudinal "cantilever" collapse of the headhing in advance of the first section of completed ring	Paris, Massenburg	Müller
A7	Collapse due to the crown excavation being too far advance of the closure of the ring. [fig 13]	Paris, Bochum #1 Sâo Paulo 93	Kuhnhenn
A8	Collapse due to failure of temporary invert to the crown section. [fig. 7]	Landrücken
A9	Collapse due to bearing failure under the "elephants' feet" to the crown section	Bochum #1	Schrewe & Maidl Leichnitz & Schrewe Kuhnhenn
A10	Collapse due to structural failure of the partial completed lining - for example due to local overstressing or rock joint movements	Landrücken, Krieberg, Michaels	Schrewe & Maidl Müller Leichnitz & Schrewe Kuhnhenn
A11	"Pause in work" collapses before ring completion	Karawanken	Schrewe & Maidl Leichnitz & Schrewe Kuhnhenn
A12	Collapses where the failure was in part due to an identifiable contruction defects	Munich #2, Munich #4, Munich #5, Munich #6	Schrewe & Maidl Leichnitz & Schrewe
	B- in the area of the tunnel with the completed primary NATM linning
B1	Collapse due to general excessive settlement or convergence	Bochum #1	Kuhnhenn
B2	Collapse due to more local overstressing usually as a result of unanticipated or unallowed for loading conditions		Schrewe & Maidl Müller Kuhnhenn
B3	Collapses largely as a result of substandard materials or significant construction defects		Leichnitz & Schrewe Kuhnhenn
B4	"Pause in work" collapses concerning the junctions of old and new parts of the NATM linning		Schrewe & Maidl Leichnitz & Schrewe
B5	Collapses due to inexpertly undertaken repairs, changes or corrections to the profile of the NATM primary lining		Schrewe & Maidl Leichnitz & Schrewe
	C- Other collapse locations and mechanism
C1	Collapses at portals - usually associated with problems of weathered or loose rock or ground. [fig. 14]	Carvalho pinto, (Funagata)	Scherewe & Maidl Leichnitz & Shrewe
C2	Collapses at break-outs from vertical construction shafts - usually associated with weak ground and/or water on the outside of the shaft construction. [fig. 9]	Munich #1

Informe sobre el NATM del Health & Safety Executive, de Inglaterra, 1996

TABLE 1: TABLE OF NATM TUNNEL INCIDENTS (INCLUDING COLLAPSES)

TABLE 2 : REPORTED CAUSE OF COLLAPSE. [see fig. 6]

Table 3.1 Failure mechanisms: Ground collapse in heading

Table 3.2 Failure mechanisms: Failure of lining before ring closure

Table 3.3 Failure mechanisms: Failure of lining before ring closure