NFF > FORTY YEARS WITH THE Q-SYSTEM

FORTY YEARS WITH THE Q-SYSTEM

As part of the celebration of ‘Forty years with the Q-system’ Nick Barton and Eystein Grimstad were invited by the Norwegian Tunnelling Society (NFF) to give an updated presentation of the Q-system. The paper titled ‘FORTY YEARS WITH THE Q-SYSTEM IN NORWAY AND ABROAD’ was subsequently written in an appropriate division of labour and finally presented by Grimstad for a large audience of tunnelling experts during the NFF Fall Conference last year. The interesting paper is included in the proceedings from the conference.
For sharing of the paper with a wider audience on the English language homepages of the Society, «Varsku her» asked the two authors for some background information as to the development of the Q-system.

Nick Barton tunnel (3) Eystein Grimstad (2)

Nick Barton (left) and Eystein Grimstad

The start and further development of the system

The Q-system was developed in 1973, with publication dated 1974.
According to Barton, the Q-system was actually an unplanned development funded by NVE – Statkraft (Norwegian Water Resources and Electricity Administration) because Statkraft had asked NGI a tough question:»Why was there such a range of deformation in Norwegian powerhouse caverns»
The question was given to Barton by division leaderBjørn Kjærnsli. Barton was not able to answer this question at first. During a hectic work period of six months a new concept was developed combining tunnel or cavern dimensions (span and height), bolting, mesh, anchoring, and sprayed concrete support, with depth or stress, and the all-important rock mass quality descriptors.The latter was mostly just given as RQD and joint spacing (or «poor/good quality») in those early days. Barton represented the hub in the development. The 1973 version of the Q-system was based on observations from more than 200 projects, 60% of these observations came from Scandinavian project case records, in particular Cecil (1970) who had suggested combining RQD with the number of joint sets.(O.S.Cecil, Ph.D. University of Illinois. His professor was Deere).

In 1993 a further 1050 cases were included. Thanks to Grimstad and his long time cooperation with the Norwegian Public Roads Administration in Sogn and Fjordane county on the West coast of Norway, the majority of these case records for the 1993 update from S(mr) to S(fr) were from Norwegian road tunnels in the western part of the country, constructed during the years between 1981 and 1993, and mainly independent of the Q-system. Based on case studies of high rock stress in tunnels combined with stress measurements, Grimstad developed an extended relation between the observed effect of stress and the SRF parmeter in the Q-formula. Additionally, some cases from India were included.

In 2002 and finally, 800 more cases from more recently constructed tunnels, mainly in Norway,were included. At that time energy absorption of S(fr) and cases with reinforced ribs of sprayed concrete were included in the support chart. This was mainly based on analysis of the support capacity of the reinforced ribs of sprayed concrete.

The people behind

«Varsku her» asked Barton for some further information as to his colleagues during the initial period and also the story behind his personal long time connection to NGI and Norway:

Some may have wondered why an Englishman got involved in tunnels in Norway, when first studying rock slopes for his Ph.D. at Imperial College in London. My former professor from civil engineering (B.Sc.) days in King’s College was a personal friend of NGI director Laurits Bjerrum. Professor Nash was also the Secretary General of the ISSMGE, whose President at the time was Bjerrum. By good fortune, an invitation to lunch in London for the poor Ph.D. student led to the offer from Bjerrum: ‘when you’re finished at Imperial College, why not come to NGI? We have lots of rock in Norway’ – or words to that effect. It was easy to be persuaded by Bjerrum to try at least a year in Norway. This has now stretched to more than forty years.

Barton’s considerably more senior co-authors of the original Q-article of 1974: Reidar Lien and Johnny Lunde, who are sadly no longer alive, were advisors concerning the engineering geology content of the article, and concerning the tunnel support and reinforcement recommendations. These were necessarily a ‘best fit’ to numerous case records in the different parts of the Q-diagram. Their long experience no doubt, helped their younger colleague develop some deeper insight, and produce a by now much cited publication. Reidar Lien, civil engineering (Ph.D. level) from NTH (NTNU) was a highly respected consultant within rock engineering. Johnny Lunde, also civil engineering (M.Sc. level) from ETH, well known within the rock engineering contracting sector with his general focus on hydropower and rock fill dam construction. No names, but not forgotten are numerous unknown colleagues i.e. case record authors in the road and hydropower sector, working at the tunnel face or in offices, who had made important observations, which benefited Q-system development.
Of course, most important of all from about 1985 was Eystein Grimstad, Cand Real. (M.Sc. level) within geology from Oslo University, now running his own company after retirement from NGI has contributed to the development of the Q-system during some 35 years. (He is also a long time member of NFF, a committee member, a contributer to NFF publications as well as a regular NFF lecturer). Honourable mention should also be made of NGI colleague Fredrik Løset, who was perhaps the most frequent user of Q besides Grimstad and Barton. Løset applied Q mostly in Norwegian hydropower development while Grimstad applied Q mostly in road tunnels, in hydropower projects in India and China, later in mining and hydropower projects South America.


The Q-system application

The Q-system is used throughout the world, in mining and civil engineering, in underground and surface mines, at dam sites, and in tunnels and caverns of all types. The system, provides direct links to support and reinforcement requirements for tunnels and caverns, and also has links to tunnel deformation, deformation modulus and seismic velocity, all of them stress-dependent.

From 1974 to 1993, the Q-system tunnel and cavern support recommendation was B + S(mr) – systematic bolting, chain link and mesh-reinforced sprayed concrete. The update to B+S(fr) which was chiefly the result of Grimstad’s numerous non-Q-system case records was actually overdue, as both in Norway and Sweden there was early use of steel-fibre reinforced sprayed concrete (1979-1981 in Norway, first in hydropower projects then in road tunnels). The introduction of RRS in the Q-system was published in Norway and Switzerland 2002, whereas the support diagram was slightly modified in 2007.
The Q-system development, and its gradual widespread use abroad, was initially exposed to some prominent critics in Norway. Fortunately, times have changed. To-day the use of the Q-system is a standard requirement for rock classification by the major infrastructure developers in Norway and abroad. Internationally, the term ‘Q-value’ has become a household term within tunnelling in many countries, ‘low Q-values’ is listed as the most commonly used keynote phrase used in the relevant environment.

Barton, N. and Grimstad, E. 2014, Forty years with the Q-system in Norway and abroad. Fjellsprengningsteknikk, NFF, Oslo, 25p

A short presentation of the two authors:

Nick Barton was awarded a Ph.D. in 1971 from Imperial College, London and followed this with two periods at NGI, from 1971-1980 and 1984-2000. During the latter period he was a division director and then a technical advisor, until starting his own consultancy Nick Barton and Associates in 2000.
He developed the Q-system in 1974 and co-developed the Barton-Bandis joint behaviour criterion in 1982. He developed the Qtbm prognosis method in 2000 and most recently Qslope in 2015. He has consulted in thirty-five countries on hydroelectric project tunnels, caverns and large dams, on metro tunnels and station caverns, and on nuclear waste site characterization in five countries including the USA where he also worked for four years.
Eystein Grimstad was awarded his B.Sc. in Geology from the Oslo University in 1968, served as Engineering Geologist 1970-71 for the National Defence Construction Service and obtained his M.Sc. in Geology 73 also from the university of Oslo. In 1972 he was employed as engineering geologist, Public Roads Administration, Road Research Laboratory and Construction department until 1986 when he moved to NGI as Senior Engineering Geologist. He was later Deputy Manager and Discipline Director of the rock engineering and avalanche division. The last years he worked as technical advisor. He has consulted in 16 countries on road tunnel projects, underground mines,hydropower projects and rock slides in general. Grimstad established his own consultancy service 2011.

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