From the mid-1950s through to the early 1960s the Snowy Mountains Hydro-Electric Authority (SMHEA) developed a method to prevent large tunnels and caverns from collapse through the use of patterned rock bolting, with bolt placement designed according to the rock structure. The methodology was shared internationally and was adopted worldwide; it and the hardware remain essentially the same as those developed by the Snowy Mountains Authority.[1]
The Cooma Rock Bolting Development Site was within the property of the Authority's Scientific Services Laboratory where laboratory testing of the rock bolting methodology was performed and developed. The site in Lambie Gorge is where "pull-out" tests were undertaken to prove a rock-bolt anchorage that was as strong as the bolt itself. The site, which is accessible to the public, displays drilled holes and remnant rock bolts in the rock faces where the testing was performed.[1]
Many people were engaged within several engineering laboratories of the SMHEA, the civil design office and at the underground construction sites themselves for the massive Snowy Mountains Hydro-Electric Scheme. In addition, efficient installation techniques were devised to maximise the effectiveness of rock bolting for all its benefits to a project. The work in the gorge on successive occasions led to the approval for the commercial supply for rock bolting components under a series of underground construction contracts for the Scheme.[1]
Permanency of the rock bolting design was crucial to its full development and acceptance. This came from sealing the whole bolt system and by transferring the tensile force from bolts positioned in a pattern across the full span into a lasting compression and locking force. This aspect of the development was proven in the laboratories and refined under contract conditions at the construction sites.[1]
The Cooma Rock Bolting Development Site represents a suitable location for recognising the development of pattern rock-bolting and its contribution to the engineering discipline of rock mechanics. It was a SMHEA team effort led by engineering management that delivered very significant achievements in tunnelling speeds that regularly set new world records together with very large savings in construction costs and improved construction worker safety; it also engendered enthusiasm and pride in the project work of the Authority.[1]
The Rock Bolting Development Site was declared a National Engineering Heritage Landmark by Engineers Australia on 18 October 2009 when a plaque and interpretive sign were unveiled at the site. The Landmark is the highest level of heritage recognition accorded by Engineers Australia. The event was timed to coincide with the celebration of the 60th anniversary of the Snowy Mountains Scheme.[1]
Rock Bolting - the detailed description and justification
Rock bolting in hard rock involves drilling a hole into sound rock at the excavated face (commonly between 1.50m and 6.00m deep depending on the conditions and rock structure), with a diameter to suit an expansion unit anchor - often about 45mm diameter. A steel rod - the bolt, is then inserted with an expansion unit at the embedded end. At its exposed end the bolt is threaded and fitted with a nut under which is a small steel plate that bears on a conical rubber seal to seal the hole entrance when grouting is taking place. Screwing the nut down onto the plate and thus the rock surface, causes the embedded expansion unit to expand and anchor the bolt in the hole, this in turn allows a predetermined tension to be applied to the bolt. The aim is to have the anchor hold the full elastic tensile strength of the bolt. The hole surrounding the bolt is then filled with non-shrinking grout in a way that displaces the air. When the grout sets, it forms a permanent bond between the bolt and the surrounding rock.[1]
When the bolt is tensioned by the nut against the plate at the surface, the compressive and transverse forces lock the layer of rock against further movement. The forces induced by tensioning the bolts create a pre-stressed membrane across the surface of the excavated rock face which neutralises the internal forces in the rock.[1]
The use of non-shrinking grout enables the bolt components to transfer load to the adjacent rock over its whole length, as well as providing an inhibiting environment against corrosion. The formula for the non-shrinking grout which exactly compensates for the shrinkage of normal grout, was in itself, an inspired innovation by engineers of the SMHEA Scientific Services Laboratories.[1]
Pull-out tests were conducted at the Rock Bolting Development Site to obtain data that would show the anchorage strength compared to the strength of the bolt. A dozen or so rock bolts at the site were used to prove the effectiveness of the grouting and the strength of the anchorage.[1]
Many other steps were taken in the scientific laboratories of SMHEA to make an integrated, fully developed rock bolt reinforcement system that remained as a permanent structure, protected from corrosion.[1]
In most instances rock bolting can replace the need for surface steel supports and the accompanying over-excavation to accommodate them, and it can avoid the need for separate concrete support of underground excavations.[1]
It has been estimated that rock bolting reduced the steel required for support to one eighth of that required using conventional methods. It also saved the cost of over-excavation (and removal of the additional excavated rock) to accommodate supports and/or lining. Contractual pricing at the time showed a 45% increase in cost for fully concrete lined tunnels where light steel external supports were used instead of rock bolts. While much time and labour were saved by these excavation benefits, they also enhanced tunnelling safety. It was also an additional time-saver in that the rock bolts needed to be installed immediately after each advance of the tunnel excavation and simultaneously with the next face drilling and face exposure, before the laying of explosive charges in these holes.[1]
Location of the Rock Bolting Development Site
The Rock Bolting Development Site on Cooma Back Creek in Lambie Gorge was deliberately chosen for geological reasons because the mineralogical composition of the Cooma gneiss was similar to the granite in the known construction sites in the Snowy Mountains. These sites were for the underground hydro-electric power stations, Tumut 1 and Tumut 2 and their associated tunnels.[1]
The other factor giving rise to the usefulness of the Rock Bolting Development Site was that it was near the Engineering Laboratories of Scientific Services Division of SMHEA. These laboratories were where the testing personnel worked with their testing apparatus, both fixed and portable. All this land was then under the ownership of SMHEA and had been in use for six years in connection with other experimental work associated with the laboratories. The original SMHEA building for Engineering Materials and the storage buildings still stand (at 2016). In the years of testing activity a foot bridge at the height of the flood plain allowed for the crossing of Cooma Back Creek to the Rock Bolting Development Site from the laboratories.[1]
Description
The Rock Bolting Development site
The Rock Bolting Development Site is located on a bank of Lambie Gorge through which Cooma Back Creek flows. The site is accessed from Sharp Street (Snowy Mountains Highway) in central Cooma, near the Park commemorating the "Southern Cloud" airliner, by a Public Reserve pathway along the bank of the Cooma Back Creek, via the Cooma Agricultural and Pastoral Society Showgrounds and the Cooma Bowling Club.[1]
The site comprises a natural rock face into which holes have been drilled. Bolts of various designs project from some of these holes. Blasted fallen rock in front of the main test area is evidence of a succession of test faces within the span of usage of the test site.[1]
There are two main areas where the rock bolting experimental tests were conducted. A succession of tests were conducted in the area at the downstream end of the gorge.[1]
As at 4 December 2013, the holes and bolts were reported to be in excellent condition as they had not been disturbed. The broken rock and bolts from previous experiments are still in place.[1]
The site retains many of the bolts and drilled holes of the original field tests.[1]
A succession of test faces is evident by the blasted fallen rock in front of the main test area. This was undertaken within the span of the testing at the site.[1]
Heritage listing
Heritage boundaries
The Rock Bolting Development Site is of state heritage significance as the location of field testing of a pioneering Australian methodology for the permanent support of underground excavations in hard rock, using patterned rock bolting. The practice made tunneling safer, faster, and less expensive than earlier methods and quickly spread worldwide; it continues with little change today.[1]
The drilled holes and remnant rock bolts exposed in the rock faces of Lambie Gorge are evidence of where "pull-out" tests were undertaken to prove a rock-bolt anchorage that was as strong as the bolt itself.[1]
Rock bolts had been used in coal mines from 1912 primarily to attach loose slabs to more stable rock layers, and their use began in hard rock in Sweden in 1939.[1]
However, the approach was empirical without theoretical guidance or the backing of laboratory experiments. The methodology for the permanent support of underground excavations in hard rock was developed by the Snowy Mountains Hydro-Electric Authority between the mid-1950s and the early 1960s, through design research, coupled with testing, measurement and trials.[1]
The place is important in demonstrating the course, or pattern, of cultural or natural history in New South Wales.
The Rock Bolting Development site is of state heritage significance for its role in the history and development of the applied science of rock mechanics in NSW, Australia and internationally. It was the site at which a quantum leap in knowledge, methods and techniques of rock excavation and tunnelling were developed in the 1950s and 1960s. The new methodology led to a significant reduction in the cost of rock excavation and tunnelling, vast improvements in safety of workers and increased speed at which rock tunnelling projects could be completed.[1]
The place has a strong or special association with a person, or group of persons, of importance of cultural or natural history of New South Wales's history.
The Rock Bolting Development site is of state heritage significance for its strong association with the widely acclaimed Snowy Mountains Hydro-Electric Authority and its expert professional staff. The new methodology had significant associations with major tunnelling contractors.[1]
The place is important in demonstrating aesthetic characteristics and/or a high degree of creative or technical achievement in New South Wales.
The Rock Bolting Development site is of state significance for its aesthetic and technical values in NSW. The aesthetically distinctive rock face and scattered remnant shards are a strong visual representation of the creative and lateral thinking leading to the ground-breaking research in the science of rock mechanics.[1]
The place has a strong or special association with a particular community or cultural group in New South Wales for social, cultural or spiritual reasons.
Regarded as the most significant engineering development made on the Snowy Scheme, the Rock Bolting Development site is of state significance as it is held in high esteem by the engineering fraternity in NSW and Australia.[1]
The place has potential to yield information that will contribute to an understanding of the cultural or natural history of New South Wales.
The Rock Bolting Development site, with its still evident bolts and bore sites and the rock shards dislodged during experiments, is of state heritage significance for its potential to demonstrate the process of developing the rock bolting techniques in NSW. The site can also demonstrate the precedence of the work of the Snowy Mountains Hydro-Electric Authority and its impact in the engineering fraternity worldwide.[1]
The place possesses uncommon, rare or endangered aspects of the cultural or natural history of New South Wales.
The Rock Bolting Development site is of state heritage significance as it is the only site where such activity was undertaken in Australia.[1]
The place is important in demonstrating the principal characteristics of a class of cultural or natural places/environments in New South Wales.
The Rock Bolting Development site is of state heritage significance as a representative location for engineering experimentation that contributed significantly to the development of engineering science in NSW, Australia and the world.[1]
The Snowy Mountains, known informally as "The Snowies", is an IBRA subregion in southern New South Wales, Australia, and is the tallest mountain range in mainland Australia, being part of the continent's Great Dividing Range cordillera system. It makes up the northeastern half of the Australian Alps and contains Australia's five tallest peaks, all of which are above 2,100 m (6,890 ft), including the tallest Mount Kosciuszko, which reaches to a height of 2,228 m (7,310 ft) above sea level. The offshore Tasmanian highlands makes up the only other major alpine region present in the whole of Australia.
Underground hard-rock mining refers to various underground mining techniques used to excavate "hard" minerals, usually those containing metals, such as ore containing gold, silver, iron, copper, zinc, nickel, tin, and lead. It also involves the same techniques used to excavate ores of gems, such as diamonds and rubies. Soft-rock mining refers to the excavation of softer minerals, such as salt, coal, and oil sands.
The Kosciuszko National Park is a 6,900-square-kilometre (2,700 sq mi) national park and contains mainland Australia's highest peak, Mount Kosciuszko, for which it is named, and Cabramurra, the highest town in Australia. Its borders contain a mix of rugged mountains and wilderness, characterised by an alpine climate, which makes it popular with recreational skiers and bushwalkers.
The Snowy Mountains Scheme, also known as the Snowy Hydro or the Snowy scheme, is a hydroelectricity and irrigation complex in south-east Australia, Near the border of NSW and Victoria (Australia). The Scheme consists of sixteen major dams; nine power stations; two pumping stations; and 225 kilometres (140 mi) of tunnels, pipelines and aqueducts that were constructed between 1949 and 1974. The Scheme was completed under the supervision of Chief Engineer, Sir William Hudson. It is the largest engineering project undertaken in Australia.
Cooma is a town in the south of New South Wales, Australia. It is located 114 kilometres (71 mi) south of the national capital, Canberra, via the Monaro Highway. It is also on the Snowy Mountains Highway, connecting Bega with the Riverina.
Cabramurra was the third-highest permanently inhabited town on the Australian continent, situated at 1,488 metres (4,882 ft) in the western Snowy Mountains of the Great Dividing Range, in the state of New South Wales. It is 82 metres (269 ft) lower than Dinner Plain in Victoria, and 272 metres (892 ft) lower than Charlotte Pass Village in New South Wales. The last residents are scheduled to leave the town in January 2018 with the current workforce housed being replaced with drive-in/drive-out staff. The name Cabramurra may be derived from Wiradjuri gambirra marra.
Adaminaby is a small town near the Snowy Mountains north-west of Cooma, New South Wales, Australia, in the Snowy Monaro Regional Council. The historic town, of 301 people at the 2016 census, is a trout fishing centre and winter sports destination situated at 1,017 metres (3,337 ft) above sea level. Economic life is built around tourism and agriculture–the town serves as a service point for Selwyn Snowfields and the Northern Skifields. It is also a popular destination for horse riders, bushwalkers, fly-fishermen and water sports enthusiasts as well as a base for viewing aspects of the Snowy Mountains Scheme.
The Crotty Dam, also known during construction as the King Dam, or the King River Dam on initial approval, is a rockfill embankment dam with a controlled and uncontrolled spillway across the King River, between Mount Jukes and Mount Huxley, located in Western Tasmania, Australia.
Guthega is a ski village and the site for a hydro electric dam located in the Kosciuszko National Park, on the upper reaches of the Snowy River, on the western face of Mount Blue Cow, Snowy Mountains of New South Wales, Australia.
Eucumbene Dam is a major gated earthfill embankment dam with an overflow ski-jump and bucket spillway with two vertical lift gates across the Eucumbene River in the Snowy Mountains of New South Wales, Australia. The dam's main purpose is for the generation of hydro-power and is one of the sixteen major dams that comprise the Snowy Mountains Scheme, a vast hydroelectricity and irrigation complex constructed in south-east Australia between 1949 and 1974 and now run by Snowy Hydro.
The Tumut Hydroelectric Power Stations is a series of three hydroelectric power stations on the Tumut River in New South Wales, Australia, that are part of the Snowy Mountains Scheme.
Khancoban is a small town in Snowy Valleys Council, New South Wales, Australia. The town is located 567 kilometres (352 mi) from the state capital, Sydney and 13 kilometres (8 mi) from the state border with Victoria, in the foothills of the Snowy Mountains, near the upper reaches of the Murray River. At the 2016 census, Khancoban had a population of 304.
Tantangara Dam is a major ungated concrete gravity dam with concrete chute spillway across the Murrumbidgee River in Tantangara, upstream of Adaminaby in the Snowy Mountains region of New South Wales, Australia. The dam is part of the Snowy Mountains Scheme, a vast hydroelectricity and irrigation complex constructed in south-east Australia between 1949 and 1974 and now run by Snowy Hydro. The purpose of the dam includes water management and conservation, with much of the impounded headwaters diverted to Lake Eucumbene. The impounded reservoir is called Tantangara Reservoir.
Walter Diesendorf (1906–1975), was an Austrian-born Australian electrical engineer known for his work on high-voltage transmission systems, in particular for the Snowy River Hydro-electric Scheme.
Cooma–Polo Flat Airport is an unlicensed airfield located in Polo Flat, an industrial area of Cooma, New South Wales, Australia. The airfield is used primarily for recreational flying. Polo Flat is at a lower elevation than the nearby Cooma–Snowy Mountains Airport and is less prone to closure during bad weather and fog.
Island Bend Dam is a major ungated concrete gravity dam with a controlled spillway across the Snowy River in the Snowy Mountains region of New South Wales, Australia. The dam's main purpose is for the diversion of water for generation of hydro-power and is one of the sixteen major dams that comprise the Snowy Mountains Scheme, a vast hydroelectricity and irrigation complex constructed in south-east Australia between 1949 and 1974 and now run by Snowy Hydro.
The Snowy Monaro Regional Council is a local government area located in the Snowy Mountains and Monaro regions of New South Wales, Australia. The council was formed on 12 May 2016 through a merger of the Bombala, Cooma-Monaro and Snowy River shires.
Royal Hotel is a heritage-listed Australian pub at 59-61 Lambie Street, Cooma, Snowy Monaro Regional Council, New South Wales, Australia. It was built from 1858. It was added to the New South Wales State Heritage Register on 2 April 1999.
The Cooma railway station is a heritage-listed former railway station on the Bombala railway line at Bradley Street, Cooma, Snowy Monaro Regional Council, New South Wales, Australia. The original design of the station was attributed to John Whitton. The station complex was built from 1889 to 1950. The Cooma Monaro Railway is based at the station and is opening a heritage railway museum in the restored staion building in December 2022. The station was added to the New South Wales State Heritage Register on 2 April 1999.
Old Adaminaby and Lake Eucumbene are the heritage-listed former town of Adaminaby and the reservoir that flooded the town, now at Eucumbene, Snowy Valleys Council, New South Wales, Australia. The town was established in 1830. The reservoir was designed by the Snowy Hydro Electric Authority and built from 1956 to 1958 by the Authority. It is also known as Old Adaminaby and Lake Eucumbene, including relics and movable objects, Eucumbene River, Eucumbene Valley, Old Adaminaby Remains, Old Adaminaby Ruins and Old Adaminaby Drowned Landscape. The property is owned by Snowy Hydro Limited, a statutory corporation owned by the governments of Australia, New South Wales and Victoria. The site was added to the New South Wales State Heritage Register on 3 June 2008.
DG Moye, Head of Engineering, Geology Branch (1956). SMHEA memorandum 27/8/1956: identifying the site for rock bolting experiments.{{cite book}}: CS1 maint: multiple names: authors list (link)
Moye, DG. Daniel George Moye: Personal Papers MS5861.
EB Pender, AD Hosking, RH Mattner (1963). Grouted Rock Bolts for Permanent Reinforcement of Major Underground Works.{{cite book}}: CS1 maint: multiple names: authors list (link)
Engineers Australia, Monaro Group (2006). Lambie Gorge Rock Bolting Heritage Site: Management Plan Outline.
Brown, ET (1999). Rock Mechanics and the Snowy Scheme.
Professor TJD Leech. Professor TJD Leech: personal papers MS 4837.
RT Brodie & AD Hosking (1962). SMHEA Engineering Construction Materials Report No. SM 1309. May 1962. Field Pull out Tests on Strengthened Bayliss-Jones-Bayliss quick set rock bolt anchorages (Para 3.2).
Mills, WB (2009). The Snowy Men Behind Tunnel Rock Bolting.
Mills, WB (2006). Index of Reference Documents: Engineering Heritage of National Significance -- Rock Bolting & Speciality of Rock Mechanics, Rock Bolting Development Site.
Mills, WB (2006). Personnel credited with substantially contributing to the Engineering of the Rock Bolting Technology and the engineering discipline of rock mechanics.
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