23–24 April, 2015 - Conference

Elangeni Maharani Hotel, Durban

25 April 2015 - Half Day Technical Visit

Harbour Entrance Tunnel Site Visit and Harbour Boat Cruise

 

This conference is in response to the Civil and Mining industry being under immense pressure to deliver projects fast, efficiently and as safely as possible. Mechanised underground excavation and support installation is proving to be an invaluable and cost effective tool in the execution of a project. Technology exists for mechanised excavation where tunnels can be excavated from as small as 300mm to in excess of 18 metres in order to access ore bodies, build road or railway tunnels, facilitate the installation of utilities, construct storage caverns for gas and oil, etc.

It is recommended that delegates interested in the mining application of tunnel boring attend both days.

 Registration Form

 Sancot - programme

 SANCOT Sponsor Opportunities Conference 2015(1)

 SANCOT-Second Announcement

harald3Harald was born in 1932 in Hamburg Germany. He went to school there until he was sent to Southern Germany to avoid the bombing during World War 2. Toward the end of the war he returned to Hamburg to help support his family in the aftermath of the war. After school he joined the Post Office in Hamburg and worked there for a short time. In about 1953 Harald came to South Africa, to join the Government Mines Training School and worked at Daggafontein and in the Klerksdorp area. He hoped to study mining at the University of the Witwatersrand, but eventually returned to Germany and studied at the Clausthal University of Technology. While there he was reunited with his best friend's widow, Else, and on graduating, returned with her and her son Jens to South Africa, where they married.

Once here he began work at Rand Mines' Durban Roodepoort Deep Mine in 1963 or 4. During the next 6 years he seems to have been involved in Rock Mechanics. At his instigation, a deep level tunnel on that mine was developed with an asymmetrically arched roof to mitigate stress effects. During the same period Harald completed a PhD at Clausthal, with research on stress measurement using overcoring. The stress regime at depth on DRD was measured as part of this research.

In 1970 he completed his thesis and was awarded his doctorate. Shortly after he left DRD and worked as an independent for a German company in Mocambique and other areas. The endeavour came to an end due to financial problems and Harald joined JCI as its first Group Rock Mechanics Engineer. There were no rock mechanics departments on individual mines in those days.

In the next 5 years the Chamber of Mines Group Rock Engineers Subcommittee and the Rock Mechanics certificate were established. Initially the Group Rock Mechanics Engineers were the examiners for the exams. They also examined the candidates underground during the practical exam.

In 1979 and 80 Harald began building up JCI's Rock Mechanics Department, sending his selected team member to Dr Stan Patchet's Anglo American Rock Mechanics unit in Welkom for training. Several later prominent Mining and Rock Engineers went through this process.

In 1979 he also had a serious motor car accident on the way home from one of the mines and spent months in hospital. He injured his legs, walking with a stick for years afterwards.

The experience of his staff was that he was prepared to back them up against the sometimes ruthless politics of JCI's head office and management.

Harald enjoyed sailing and kept a Muira keel boat on the Vaal Dam, where he often spent the weekend with his family, sleeping on the boat. In the 80s he got his skipper's license for ocean sailing off Durban, but after a couple of experiences of ocean cruising he lost interest in long cruises due to the loneliness and tedium.

He prided himself on being a linguist often correcting the English language of reports and letters. He also participated in Alliance Francais for many years. He was also a stickler for the correct notation of the metric system.

Harald questioned everything and loved debate. He had a wide interest in history, language and culture and loved to discuss these over a glass of wine.

He and his family explored much of Southern Africa in his Jeep Gladiator or Wagoneer, visiting remote natural areas and game reserves. They also travelled widely to Europe, Asia and America.

Harald reluctantly retired from JCI in 1992, but continued to travel and enjoy life for many years.

In the past 5 years he suffered from Parkinson's, which became increasingly debilitating. He passed away on 29 January 2015.

He is remembered fondly by many of those who worked with him, as well his family and friends.

A memorial service was held on the 15 February, attended by a very large number of friends, family and colleagues.

Eulogy by John James

This conference is in response to the Civil and Mining industry being under immense pressure to deliver projects fast, efficiently and as safely as possible. Mechanised underground excavation and support installation is proving to be an invaluable and cost effective tool in the execution of a project. Technology exists for mechanised excavation where tunnels can be excavated from as small as 300mm to in excess of 18 metres in order to access ore bodies, build road or railway tunnels, facilitate the installation of utilities, construct storage caverns for gas and oil, etc. It is recommended that delegates interested in the mining application of tunnel boring attend both days.

23–24 April, 2015 - Conference

Elangeni Maharani Hotel, Durban

25 April 2015 - Half Day Technical Visit

Harbour Entrance Tunnel Site Visit and Harbour Boat Cruise

Click Here to read more

Dear Members
 
Please follow the link to the latest bi-annual newsletter. Stories and articles are always welcome. Please email Paul Couto at Paul.Couto@Harmony.co.za for enquiries.

Download the PDF version: pdf  SANIRE Newsletter_Volume 1_Issue 1_January_2015 (4.31 MB)

or download the .pub version to publish the newsletter youreslf: default  SANIRE Newsletter_Volume 1_Issue 1_January_2015 (22.46 MB)

mike robertsDr Michael Roberts

26 January 1950 - 5 February 2015

Mike’s funeral took place on 11 February at St Michael’s Anglican Church in Bryanston. Mike’s wife, Kim, asked if I would pay tribute to Mike’s contribution to rock engineering research, and I was honoured to do so on behalf of our community. William Joughin asked if I would send a transcript of my eulogy to SANIRE. Here it is.

Kim, Lindsay and Georgie, family and friends, I want to honour Mike’s contribution to the science and practice of rock engineering in South Africa. I first met Mike when I joined the Rock Engineering Programme at CSIR in 1993. Mike was initially my mentor, as he was for many other young (and not so young) scientists and engineers. Over the next 15 years he became my colleague and friend.

Mike completed his BSc Honours in Geology at Wits in 1974 and his MSc in structural geology and rock mechanics at the Royal School of Mines, Imperial College in 1977. He then joined Randfontein Estates Gold Mine. He became the Rock Engineering Manager in 1981 at the age of 31 after getting his Rock Engineering Certificate.

Mike joined the Chamber of Mines Research Organisation, aka COMRO in 1985 (which became the Mining Technology Division of the CSIR, aka Miningtek, in 1993) and began a career in research that lasted 23 years. Mike’s tenure at CSIR was during a period that was something of a golden age for rock engineering research in South Africa. During this time

  • Mike made major contributions to the research conducted under the auspices of the Mine Health and Safety Council’s SIMRAC programme and the DeepMine Collaborative Research Programme, particularly with respect to the support of the face area of the stope, the most dangerous area of the mine. Stope support was the subject of his PhD in mining engineering, which he completed through Wits in 1999. The methodology he developed became the industry standard.
  • He authored or co-authored more than 50 papers, chapters in three rock engineering textbooks, and many research reports.
  • He was an NRF rated researcher.
  • He was the Manager of the Rock Engineering Programme at CSIR for four years (1996-2000), with a staff of between 70 and 90 scientists, engineers and technicians. Thereafter he stepped back onto the research track as a Research Fellow. He left CSIR in 2008 to join the consultancy firm, TWP.

That’s the data, but let me tell you more about Mike the rock engineering researcher.

Engineering may be defined as “the art or science of making practical application of the knowledge of pure sciences (such as physics, chemistry and geology)”, for example, to construct machines or to mine ore. Rock is often used as a metaphor for something that is strong and enduring. We who work in deep mines (and South African gold mines are, by far, the world’s deepest) know that highly stressed rock can be unstable and dangerous. Rock engineering is the discipline that seeks to master rock: to design and construct shafts, tunnels and stopes so that the ore can be mined safely and profitably. And this is the discipline of which Mike was a master.

Predicting the behaviour of rock is as much an art as a science, and we rely on “rock engineering principles” and often appeal to “engineering judgement”. One of the cardinal rock engineering rock principles is to “mine away from danger”. Mike was a key member of the Rockburst Task Force, which conducted forensic investigations into rockburst accidents. During a four-year period (1995-1998) we investigated over 30 rockbursts that had claimed the lives of more than 100 mine workers. In order to gather fresh evidence, we would go underground as soon as possible after the rockburst. Often the rescue teams were still digging for survivors or recovering bodies, the rock mass would not yet have been stabilised, or the ventilation restored. Mike had an incredible instinct for the underground environment. He usually went underground without clinorule, tape measure, camera, or compass. Like Sherlock Holmes, he would spot clues that most of us would miss (evidence of damage to rock, props, packs and bolts), and reconstruct the sequence of events, and recognise the sins of omission and commission that had contributed to the event. This took courage, endurance, and common sense. Mike calculated the risks carefully with a cool head.

A second rock engineering principle is “don’t resist an irresistible force with an immovable object”. Rather yield, absorb the excess energy, and keep capacity in reserve for another day”. Mike did not only apply this principle when dealing with rock and stope support, but also to people. Mining is a tough industry, but Mike was always quietly-spoken, and sought to persuade and encourage, rather than to command or intimidate.

While I have focused on his work achievements, we were very aware that rock engineering was not his sole priority. There were the four Fs: Family, Fishing, St Francis and Fast cars. Mike worked hard and smart, but seldom late.

Mike, as a representative of your friends and colleagues at involved in rock engineering research, I salute you for:

  • Your contribution to the science and art of rock engineering in South Africa;
  • For developing methods and technologies that have helped to make mining safer and more profitable – there are probably hundreds, if not thousands, of mine workers who owe their lives to the technologies that you helped to develop;
  • For training and mentoring a generation of rock engineers; and
  • For being a true scholar, gentleman and friend.

Ray Durrheim

South African Research Chair in Exploration, Earthquake & Mining Seismology

Mineral Resources Competency, Natural Resources & the Environment Unit, CSIR

&

School of Geosciences, The University of the Witwatersrand, Johannesburg

The Contribution of Rock Engineering to the Future of Mining

“Rock Engineering to the Rescue”

sym1 copyThe 11th of September 2014 saw the SANIRE Coalfields Branch hosting the annual SANIRE symposium for the second time since the 1989 SANGORM Symposium.

One of the very first annual SANIRE symposiums was held in 1986 and there have been more than 20 symposiums since then.

The decision that the 2014 Symposium would be hosted by the Coalfields Branch was taken at the SANIRE Bosberaad Meeting held on the 19th and 20th of October 2013, and since that day it has been all systems go for the Coalfields committee. All in all various members on the committee met to discuss the arrangements and planning more than 8 times over the following 9 months in the lead up to the Symposium to discuss, amongst other Rock Engineering related aspects, the requisite planning and arrangements for the Symposium.

Due to the extremely large scope and significant amount of planning and work that goes into the hosting of such an event, the Coalfields Branch committee took an informed decision to reach out to a number of additional SANIRE members within the coal industry for help with a number of different aspects related to the Symposium.

An individual who went out of her way to assist and advise wherever possible was the aptly named “Symposium Consultant” Lelanie Prinsloo. Lelanie was also responsible for the design of the dragline and roofbolter “goggo’s”, which would later adorn the brochures and posters.

Behind the scenes the Chairman’s wife Diane Petho was working tirelessly designing and compiling all of the brochures, announcements, posters, name tags, name lists and also selecting and wrapping the gifts, to ensure that everything on the day went along smoothly and in a professional manner.

The committee also took a decision to, as far as possible; ensure that the symposium had a more personal feel to it, for all of the delegates, from the Rock Engineering Practitioners to the Sponsor Representatives. A conscious effort was put in to ensure that each of the speakers, and event sponsors felt involved and was kept informed of the arrangements at all times.

One of the more difficult decisions that any organising committee has to make is the selection of the “ideal” venue. Due to the huge geographical area in which the Rock Engineering practitioners are located, as well as the fact that the exact number of delegates who typically attend the Annual Symposiums has been known to be particularly difficult to predict, a number of different venues had to be investigated.

One of the sponsor representatives, Danie Blom, took it upon himself to personally conduct a detailed investigation into all of the relevant different aspects of the potential venues in order to allow the committee members to make an informed decision regarding the selection of the venue.

Each venue was rated on aspects including cost, catering, parking, location, technical support etc. and based on the findings of the investigation; the committee took the informed decision that the symposium to be held on the 11th of September 2014 would be held at Glenburn Lodge.

Based on previous symposiums the initial number of delegates who were expected to attend the symposium was put at approximately 100, a number which proved in the end to be a gross underestimation.

As the date drew closer the names of delegates attending continued to pour in with the number of delegates attending having to be increased from 120 to 140 a mere two weeks before the event. Even so on the day the number of 140 proved again to be a slight underestimation with the final number of registered delegates on the day being 141.

After months of preparation, meetings and planning the day of the symposium finally dawned and 5:30am found the committee members arriving on site to finalise the venue preparation and ensure that everything was ready for the delegates when they started arriving at around 7:00am.

Thankfully, one of Mother Nature’s greatest variables, the weather, played along and ensured that the picturesque venue that Glenburn Lodge is could be enjoyed in all its splendour.

sym2 copy

 

sym3 copy

Generally the symposium was a huge success with the wide variety of topics ensuring that all of the approximately 141 delegates were kept interested throughout the day and that everyone was able to take home a number of valuable learnings relevant to their specific work environment.


The exceptionally high standard of presentation and supporting research was set from the onset with the key note address being given by Professor Nielen van der Merwe of Stable Strata Consulting who presented the most current research related to strength calculation formulas for coal pillars and the fact that so often in life, the more we know, the more what we thought we know, we need to change.

sym4 copy

The presenters who followed maintained the same high standard of research and presentation with topics ranging from, the monitoring of surface subsidence using satellite imaging techniques to, the effects of extremely high temperatures on the mineral properties of rocks and what geotechnical conditions could be anticipated when South Africa’s mining industry reaches ultra-deep level mining areas.

True to the common saying “last, but not least,” a highlight of the day was the presentation by Pieter Colyn which was in fact the very last presentation of the day, in which Pieter discussed his paper on the “Legal Liability of Rock Engineering Personnel,” a presentation which was unusually well attended for its position in the day’s proceeding, and quite understandably so.

As can be expected, there were a number of glitches on the day including some technical difficulties and simply the fact that the sheer quantity and value of the information which was to be communicated via the presentations on the day, resulted in what turned out to be a considerably long day, and a number of presentations running over time, literally “eating” into the break times and therefore impacting on the opportunity for delegates to network.

That said, all in all, it is safe to say that the 2014 national SANIRE Symposium, hosted by the Coalfields Branch, was a huge success, and that each and every delegate who attended on the day would have left that evening knowing that it was a day full of learnings and opportunities and ultimately one which was very well spent.

A big thank you needs to be extended to all of my fellow Coalfields Committee members for making the event a success. Also a special word of thanks needs to be extended to the videographers on the day, Dewald Swanepoel and Carl Krog, as well as the photographers Danie and Frik Blom, the father and son duo, for all their hard work behind the scenes.

Also a final word of thanks needs to be extended to all of our 16 sponsors, and 16 speakers for affording us the opportunity to present the Symposium.

We look forward to seeing you all next year when we as SANIRE, take the success of the 2014 Symposium and use it as a spring board to propel the SANIRE members as well as the mining community as a whole to even greater heights.

noelInterview questions

Full Name

Noel Delphin Fernandes

Position

Group Rock Engineering Manager

Company/ Organisations

Impala Platinum Mines

Date and Place of Birth

1961/12/24 Virginia OVS

Education

Barberton High School

First Job

Onsetter School Holidays, Electrical Apprenticeship Sheba Gold Mine in Barberton, then started as a learner official mining at Buffelsfontein Gold Mine.

Personal Best Achievement/s

Establishing a great rock engineering department which has stayed together for so many years. When rock engineers were travelling around following all the best paid jobs the Impala team stayed together. We fight a lot but all for the right reasons.

Philosophy of Life

If you don’t like it don’t do it. Life is too short to do something you don’t like to do.

Favourite Food/Drink

Typically porra, perri perri prawns and Coke

Favourite Sport

To watch Rugby and Athletics and did karate for many years. Now I get “milt steek” watching sport on TV.

Philosophy of Life: If you don’t like it don’t do it.
Life is too short to do something you don’t like to do.
 

 

1. How did your career in the mining industry begin and where are you now?

Started as a learner official mining 1983 and joined rock engineering in 1985 as an observer.

2. Why did you choose Rock Engineering?

Did not have the “balls” to do mining and asked for a transfer to rock engineering.

3. Please tell us a bit more about your career journey?

Not a nice story to tell but let me give it a shot. I was asked to leave the apprenticeship training facility at Anglovaal because of an argument with my trainer Mr Murning. Fortunately there was a vacancy for a mining learner official at Buffeltsfontein Gold Mine Gencor. Did not enjoy production and got into trouble for always arguing with my line management, was then transferred to the rock engineering department and have never looked back. Left Buffelsfontein Gold Mine in 1989 to join Vaal Reefs as an SCO, then joined Bafokeng South Platinum Mine (Impala Platinum) as a Rock Engineer stayed with them until 1996, joined Rustenburg Platinum from June 1996 to December 1997 and then returned to Impala Platinum end of 1997. Was appointed as the Rock Engineering Manager for Impala in March 1999 and was appointed Group Rock Engineering Manager for Implats in 2008.

4. In your opinion, what are some of the challenges that the fraternity is currently facing?

Firstly a lot of people have passed their rock engineering certificate lately and been pushed into rock engineering positions without the necessary experience, but this is a South African problem and we see it happening in the mining fraternity as well. Secondly the youngsters are getting involved with the setting of the examinations and practical exams. I believe here we lose a lot of the practical, hands-on issues that don’t get mentored to the newer generation. We need to blame the older generations as we don’t want to get involved enough and it will be nice to see them getting more involved again. Thirdly because the rock engineering fraternity is used by management and to a small degree the DMR to act as “policemen” to measure compliance, it is now becoming the responsibility of the rock engineering department to insure compliance. Compliance needs to stay the responsibility of line management.

5. What are some areas that you believe will become of increasing importance in the near future of the rock engineering discipline?

Historically Rock Engineering departments were small, but are getting larger and one will need to learn the skill to work with people.

“Surround yourself with people with different skills and people you can trust.” 

 

6. What advice would you offer people aspiring to be in your position?

Be honest with yourself and with management, never shy away from telling the truth. It will at times cause constellation, remember rock engineers will never win a popularity contest with line management.

7. Who is your role model/ mentor?

I have been very fortunate to have worked with great leaders in the rock engineering. The first to come to mind is Roger More-O-Farrell, he was phenomenal with the rock engineering principles and he has the ability to surround himself with strong rock engineers who understood mining as well as rock engineering. In mining I worked for Senior Managers who were outstanding in their jobs such as John Smithies and Pieter Anderson but I must mention Mr Paul Visser who helped develop my management skills on how to get the job done and to trust the people working with me. Lastly Tinus Gericke has brought back the passion for the “job”.

8. What is the best advice you have ever been given?

The best advice I have ever been given was “Surround yourself with people with different skills and people you can trust.” I have been blessed to be surrounded with great hard working people of whom many have better skills than I have.

9. Who has influenced my life the most?

It might sound cliché my wife Anrea has really turned my life around, taught me to be more patient and caring. My team will testament to that, they say I have changed a lot and for the better. My daughters, they keep my feet on the ground, ready to tell me if I have messed things up.

andreasInterview questions

Full Name:

Andreas (Andre) Petrus Esterhuizen

Position:

Rock Engineering Manager - Eastern Bushveld

Company/ Organisations:

I am employed byOpen House Management Solutions, and I am a member of SANIRE and SIAMM

Date and Place of Birth:

I was born in Klerksdorp on 14 April 1981 – the same day as the Lincoln assassination and the day the Titanic struck the ice berg. (Apparently not the luckiest day of the year?)

Education:

After a brief stint at university I obtained my COM Strata Control and Rock Engineering Certificates. Following that, I obtained an Advanced Rock Engineering Certificate from Wits.

First Job:

Computer programmer for a company focused on modernising the agricultural sector.

Personal Best Achievement/s:

Professionally- to date the quality and success of the rock engineering function at Two Rivers Platinum mine, which has since become leading practise, is something that I am very proud off. As with everything, I can’t take all the credit for the success of the system, but I played a large part in the early development.

Personally, I hold black belts in three different styles of Karate and represented South -Africa internationally.

Philosophy of Life:

The saying “You don’t find yourself, you create yourself” comes to mind. I firmly believe that we are not born for a specific purpose, but that our lives obtain meaning through what we do and how we affect world and those around us.

Favourite Food/Drink:

I love shepherd’s pie and pasta and a good red wine.

Favourite Sport:

I am an avid Sharks rugby supporter and enjoy boxing and all forms of martial arts.

1. How did your career in the mining industry begin and where are you now?

I started off working in the Seismology Department at Harties in 2001, which lasted for 8 months. The following year I transferred to the Rock Engineering Department and obtained my SCO ticket. I was transferred to Two Rivers Platinum near Lydenburg in 2005, where I obtained my Rock Engineering Certificate and AREC. I am currently managing the largest department (by number of employee) within OHMS, and I am responsible for on-site contractual as well as consulting services for mines situated within Mpumalanga, Limpopo and most recently also Zambia.

‘Never present problems without solutions.’ 


2. Why did you choose Rock Engineering?

What attracted me most in the beginning of my career was the opportunity to work in a young developing field of science. I love to read and research just about anything in an effort to continually better myself and my general knowledge, and this field suited my personality perfectly. There are no quick fixes, in order to be successful you must have a passion for understanding what you see around you, and aim to find practical solutions to real problems.

3. Please tell us a bit more about your career journey?

I started off in OHMS’s Seismology Department as a Seismic Processor at Harties. During this period I was exposed to- and became interested in Rock Engineering, as both departments were managed by our company. When a vacancy opened up in the Rock Engineering Department I requested to be transferred and became a Learner Strata Control Officer. I obtained my SCO ticket 4 months later. After that I was transferred to the Eastern Bushveld where I matured into a qualified Rock Engineering Manager. I have been very fortunate in my career to date to be associated with both fantastic Rock Engineers and Mine Managers who had significant influences on my career.

4. In your opinion, what are some of the challenges that the fraternity is currently facing?

The level of competence within the fraternity is definitely increasing and we are producing competent engineers. However, I recently became aware of the fact that most rock engineers have very limited exposure. Whilst they might be experts on their specific mines and environments, they falter as soon as their environments change. This leads to complacency and stagnation. I am in favour of a system whereby all qualified rock engineers are required to refresh their qualification on a set and regular basis.  

On the flip side, the level of competence in the mining industry – especially on the production front, is decreasing rapidly. This results in rock engineers spending more time policing, and less time on actual design work, which obviously influences job satisfaction.

"Philosophy of Life: The saying “You don’t find yourself, you create yourself” comes to mind. I firmly believe that we are not born for a specific purpose, but that our lives obtain meaning through what we do and how we affect the world and those around us.”

 

5. What are some areas that you believe will become of increasing importance in the near future of the rock engineering discipline?

As mining continues to advance deeper and deeper, we need to obtain a better understanding of rock mass behaviour to stress. Stable pillar design also has a lot of room for improvement. As a gadget lover, I would love to see more research and the introduction of more electronic technologies such as digital image processing, pattern recognition and more sophisticated means of measurement.

6. What advice would you offer people aspiring to be in your position?

Unfortunately there are no shortcuts. Work hard, be meticulous, and be interested in what you do. My three favourite quotes are:

  1. You are the product of your environment, so choose carefully the environment that will best develop you toward your objective.
  2. Never present problems without solutions.
  3. You don’t always get what you deserve, but you always get what you work for.

7. Who is your role model/ mentor?

I have a lot of role models. There are many of my friends, family members, colleges and even subordinates that I look up to and who’s opinion I regard very highly.

My mentor, and without doubt the largest influence in my professional career, is Koos Bosman, who has instilled in me a deep love of rock engineering, research, knowledge and red wine.

8. What is the best advice you have ever been given?

Distinguish between what is important and what is urgent” and my favourite: “Own your mistakes, and then move on”.

andreas2

William Joughin
SRK Consulting

Although this article is focused on the calculation of joint shear strengths for use in JBlock to evaluate underground rockfalls, it contains information relevant to anybody calculating joint shear strengths, in any rock engineering environment.

When designing support in JBlock, it is important to investigate the joint characteristics in a Ground Control District (GCD). Each joint set within a GCD could present a range of joint conditions from rough undulating joints with no fill, to slickensided joints with thick soft clay infill such as serpentinite. The joint shear strength will therefore be variable and will significantly affect the stability of blocks formed. It is important to capture the distribution of shear strengths in JBlock so that the analysis is representative of the GCD on which it is based.

JBlock can create a few hundred thousand blocks and then test their stability within a supported excavation. Each block is formed by combining joints from the different joint sets. The attributes of these joints (dip, dip direction, persistence and shear strength) are selected by a randomly sampling from the input distributions. The user can specify the mean and standard deviation or the minimum and maxim for each joint characteristic.

JBlock uses the classic Mohr-Coulomb model for determining joint shear strengths:

equation1

where c is the cohesion and Φ is the friction angle of the joint.

For each joint set, JBlock requires the mean and standard deviation of c and Φ These are randomly applied to individual joints using a normal distribution (at this time no other distributions are availible). It is important to input a representative distribution of joint shear strengths, but it is not critical to accurately determine the shear strengths of individual joints.

quote1Unfilled joints have no real cohesion. Uncemented, coarse joint fill material and gouge, also have no cohesion. Soft clay infills have very low cohesion and this can generally be ignored, but it may be prudent to carry out laboratory shear strength tests on these joints. If the laboratory cohesions are used, it may be sensible to make these a separate joint set (note that the joint spacing parameters should be determined for the filled joint set and not for all similarly oriented discontinuities). Quartz and calcite veins are effectively cemented and therefore have high cohesion values. If these veins commonly form bounding discontinuities in the observed rockfalls, they should be included as a separate joint set. The shear strengths of closed veins should be determined in a laboratory. Rocklab has the facilities to perform shear strength tests on natural joints. However, it is usually reasonable to ignore veins and not to use cohesion for filled joints, but this should be verified in each GCD.

Nick Barton and his colleagues have performed many hundreds of rigorous laboratory and field tests on discontinuities in rock and have published many papers on the subject. They have proposed methods for estimating the shear strength of discontinuities in the field without having to use the cumbersome tests. This work is widely used and accepted by the rock engineering fraternity internationally and appears in most rock mechanics textbooks. A few important papers are included in the references (Barton, 1973; Barton and Choubey, 1977; Barton and Bandis, 1990; Barton, 2002).

It is recommended that the following simple formula is used to estimate friction angles from data collected during a routine joint mapping exercise:

equation2

where Jr and Ja are the join roughness and joint alteration used in Barton’s Q system (Barton, 2002)

Barton considers this to be good estimate of the friction angle for joints with rockwall contact and is the only method for estimating the shear strength of filled discontinuities (Barton and Bandis, 1990, Barton, 2002 and Barton pers comm 2014). This method is demonstrated in Table 1 where example friction angles are provided for different combinations of Jr and Ja. These parameters can be estimated using Table 2 and can be easily determined during underground mapping. The distinction between joints with rockwall contact, sheared joints with rockwall contact and no rockwall contact when sheared is illustrated. It is apparent that the strengthening effect of asperities (rough undulations) is diminished with the presence of soft clay infills. The low friction angles for filled joints were assessed by Barton (1973) and results are presented in Table 3. Joints with thick serpentinised or soft clay fill could have friction angles of less than 10°.

This simple method is recommended because it provides reasonable estimates to obtain a distribution of friction angles for a joint set. Figure 1 is an example of joint set friction angle distributions.

graph1 graph2
Figure 1:    Frequency and cumulative frequency distributions of frictions angle.


It is apparent that the data contains a few discrete values of Jr/Ja, which is to be expected when using the Q tables (Table 2). There are some weak joints in this set, representing a thin fill, but no thick filled joints (lowest friction angle is 20°). The normal distribution smoothes the irregularities, but unfortunately does not provide a good fit to the data. A lognormal or beta distribution would provide a better fit, because of the large number of 20° friction angles, but these distributions are not currently availible in JBlock. This enhancement to JBlock has been suggested and will hopefully become available in the near future.

It is also important to place upper and lower limits on the distribution; otherwise the random sampling process will assign negative friction angles and friction angles greater than 90° to a few individual joints, which will lead to errors. The lower limit should be slightly lower than the lowest estimated friction angle, but not less than 2°. It is recommended that the upper limit should be 70° or less. Barton does not appear to be uncomfortable with friction angles greater than 70°, but Hoek suggests that f values greater than 70° have no practical meaning.

Barton (Barton and Choubey, 1977 and Barton and Bandis, 1990) also proposed the more rigorous Barton-Bandis model for determining the shear strength of unfilled discontinuities with rock wall contact. (Hoek provides a good summary of this method):

equation3

Where JRC and JCS are the Joint roughness coefficient and Joint compressive strength respectively and Φr is the residual friction angle, which can be determined as follows: 

 equation4

Where r is the Schmidt rebound number for wet and weathered fracture surfaces and R is the Schmidt rebound number on dry unweathered sawn surfaces. Φb is the basic friction angle, which can be determined from literature or preferably by a laboratory shear test. Note that for a dry unweathered joint, Φr = Φb.

JCS can be estimated from the profiles in Table 4. Suggested methods for estimating the joint wall compressive strength were published by the ISRM (1978). The Schmidt rebound hammer can be used for estimating joint wall compressive strength.

A further scale correction is usually required, as this method is based on test samples and observations taken over approximately 10 cm, where rockfalls and failures can occur over several metres. This correction reduces the JRC and JCS and is based on the principal that a small asperity will have a lower effect on the shear strength of a 20 m long joint, than a 1 m joint.

This method requires considerably more effort and although it is a more rigorous estimation of joint shear strength for specifically unfilled joints with rock wall contact, it has some drawbacks when being applied in JBlock.

Firstly, additional work is required to convert the results to c and Φ, the input parameters required by Jblock. It is a non-linear equation and therefore ci and ΦI will vary for different values of σn (Figure 2). The ci value is not the physical cohesion value but simply the intercept on the t axis. Hoek provides a spreadsheet based calculation method for conversion to ci and ΦI for a given σn, which is commonly used for joint analysis software that does not include the Barton-Bandis model directly. In the JBlock analysis, the magnitude of σn will vary for individual joints depending on the joint orientation and c and σ, up to a maximum of the set clamping stress in JBlock (for vertical joints). It should also be noted that for σn = 0, the model is undefined due to division by zero. The possibility of including the Barton-Bandis model in JBlock has been suggested and this may be available in the near future. This conversion will no longer be required if this is implemented.

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Figure 2:    Definition of instantaneous cohesion ci and instantaneous friction angle φi for a nonlinear failure criterion (after Hoek)

quote2Secondly, the shear strength of filled discontinuities cannot be determined with this method. Barton specifically states that the method does not apply to filled discontinuities (Barton and Choubey, 1977 and Barton and Bandis, 1990, Barton pers comm 2014). The filled joints are the weakest and are therefore more likely to cause rockfalls. It is therefore recommended that this approach should only be used when there are no filled or sheared joints in the set.

References

Barton papers can be obtained from www.nickbarton.com.

Barton, N.R. 1973. A review of the shear strength of filled discontinuities in rock. Norwegian Geotech. Inst. Publ. No. 105. Oslo: Norwegian Geotech. Inst.

Barton, N.R. and Choubey, V. 1977. The shear strength of rock joints in theory and practice. Rock Mech. 10(1-2), 1-54.

Barton, N.R. and Bandis, S.C. 1990. Review of predictive capabilities of JRC-JCS model in engineering practice. In Rock joints, proc. int. symp. on rock joints, Loen, Norway, (eds N. Barton and O. Stephansson), 603-610. Rotterdam: Balkema.

Barton, N. R. 2002. Some new Q-value correlations to assist in site characterisation and tunnel design. International Journal of Rock Mechanics & Mining Sciences 39 (2002) 185–216.

Hoek. Rock Engineering (Course Notes). www.rocscience.com.

ISRM 1978. International Society for Rock Mechanics Commission on Standardisation of Laboratory and Field Tests.. Suggested methods for the quantitative description of discontinuities in rock masses. Int. J. Rock Mech. Min. Sci. & Geomech. Abstr. 15, 319-368


Table 1:    Estimation of joint friction angle (from Barton 2002)

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Table 2:    Q parameters Jr and Ja (Barton, 2002)

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JBlock is a user-friendly tool that is used for identification of key blocks and failure potential, based on a probabilistic analysis. Input parameters, such as orientation, size and strength estimates for joints, faults and the position of hangingwall parallel discontinuities, can be considered in the analysis. The results are useful input parameters in support design and for identification of fall of ground hazards. JBlock provides results in the format of plans and charts of the probability of failure of key blocks of different sizes. The results can be compared qualitatively with calculations from numerical modelling software and rock mass ratings.


Table 3:    Shear Strength of filled joints(as presented by Hoek– Data from Barton 1973)

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Table 4:    JRC profiles (after Barton and Choubey, 1977 as presented in Hoek)

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RockTalk Nov2014                      

In July 2011, the SIMRAC project SIM100301 ‘Minimising the increasing seismic risk in the platinum sector’, was successfully completed. The main authors of this project were SiM Mining Consultants on seismology and Middindi Consultants on rock engineering.

SIM100301 looked at the causes of seismic conditions and the implications it held for mine design and practice on platinum mines. It also evaluated the performance of routine seismic hazard assessment methods and compared recommended to actual seismic monitoring practice.

SIM100301 suggested methods to improve the mining practice, the effective gathering of rock mass related information, suitable seismic monitoring procedures, and training initiatives which should focus on conditions that generate seismicity in platinum mines.

Acting on a recommendation by the COM’s RETC committee, the MHSC issued a tender in June 2014. Recently, SIM 140301, a two year technology transfer project, was awarded to SiM Mining Consultants, in collaboration with Middindi Consulting and Simulated Training Solutions (STS).

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“Horizontal stress in coal mines”, ©2012 Coaltech

 

SIM 1403021 ‘Technology transfer on minimising seismic risk in the platinum mines’ aims to deliver on the SIM100301 recommendations in three ways:

  • Creating learning and awareness training material for production personnel on PGM mines to improve seismic risk management and assisting with the roll-out of this training.
  • Sourcing and revising relevant seismic training material for Rock Engineers for all commodities
  • Developing an audit protocol for seismic systems and conducting a baseline audit on each PGM producer.

The training materials for production personnel aim to use advanced and innovative technologies, supplied by STS, to provide a virtual reality learning environment that can be better understood by a workforce not overly familiar with English. The materials will be workable in the most common current training facility setup and trainers will be able to choose the most relevant sections, from modules, to integrate with existing training. Trainers can attend one of several workshops to familiarise them with the new material.

The training material for Rock Engineers already exists in various formats and this phase of the project will focus on collation, revision and distribution.

Seismic Moment: A scalar that measures the co-seismic inelastic deformation at the source. Since seismic moment is proportional to the integral of the far field displacement pulse, it can be derived from recorded waveforms. 


The audit protocol will be built on the guidelines provided in SIM100301, but will have to cater for a range of different seismic system setups: From shafts monitored by a single surface site to those with more than ten stations.The stakeholder interest in a baseline audit, nine mines have indicated active support, shows the relevance and necessity of practice reviews. Most operations do not include seismic system audits in their budgets and this project will be delivering a valuable service to a number of operations. Individual audit reports will be compiled per business unit as well as a summarising report reflecting all business units. The summary will contain statistics on equipment deployed, practices implemented, level of compliance and gaps evident between recommended and actual standard of seismic monitoring and reporting.

Invites to participate have been sent out in November to all stakeholders. The success of SIM140301 relies on active support and participation by each producer for the mutual benefit of the industry.

Friedemann Essrich, SiM (14/11/2014)

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Examples of pillar failures on PGM mines in the WBV (SIM100301).

Here is the final version of the program, for you to please distribute amongst your department and colleagues. If however there is anyone else that you would like to invite or make aware of this meeting, please feel free to forward this onto them as well. In terms of attending could you please contact either Sandor Petho or Stephen Poczik, by the latest the 18th of February 2015, so that we can cater accordingly.

Click Here for more information

The Rock Engineering exam results for October 2014 is available. Results for P3.1 can be obtained by sending an email to Yolande.jooste@harmony.co.za

The Coalfields Branch would like to extend an invitation to the annual SANIRE END YEAR FUNCTION to be held at Olifants River Lodge, between Middelburg and eMalahleni (Witbank), on the 28th of November 2014.

If you are interested in attending, please contact one of the committee members below:

Chairman: Sandor Pethö: 083 600 4158 / sandor.petho@glencore.co.za

Vice - Chairman: Stephen Poczik: 082 335 8570 / stephen.poczik@totalcoal.co.za

For more information click HERE

The SANIRE Gauteng Branch is hosting an evening lecture with a technical talk on

Topic : Risk Mitigation – Slope Stability Monitoring.

Speaker:

Huw Thomas – Principal Surveyor (Anglo American Technical Services)

Drinks and snacks will be provided.

Venue : AEL Mining Services, The Platform, Modderfontein

Time: 17H30 for 18H00 Date: 20th November 2014

RSVP to Philani Mpunzi before the 14th November 2014 by clicking on one of the boxes or by e-mail directly to pmpunzi@srk.co.za

Sponsors:

Reutech Mining

Click HERE for more information

2015_SF_Banner

 

 

The American Rock Mechanics Association invites you to submit an abstract to the U.S. annual conference on rock mechanics and geomechanics, and visit the beautiful and vibrant city of San Francisco, California.

Abstracts are sought in mining engineering, petroleum engineering, civil engineering and interdisciplinary aspects of each.

For information on the symposium, abstract submission, accommodations, and sponsorship, visit:

www.armasymposium.org

Conference Dates:           28 June - 1 July 2015

Location:                          Westin St. Francis, Union Square, San Francisco, California, USA

Abstract Deadline:           1 November 2014

Author Notification:          15 January 2015

Paper Submittal:              1 March 2015

 

Peter Smeallie
Executive Director
American Rock Mechanics Association
600 Woodland Terrace
Alexandria, VA 22302
703-683-1808 (office)
703-997-6112 (fax)
www.armarocks.org

 

Slope Stability

 

INTERNATIONAL SYMPOSIUM ON SLOPE STABILITY IN OPEN PIT MINING AND CIVIL ENGINEERING

Open pit mines are being planned to increasingly great depths, often beyond the current experience and knowledge base, with the exception perhaps of some very steep and high natural rock slopes. Despite recent advances, there remains significant challenges in understanding the mechanisms of slope behaviour and failure, and methods of stability analysis for such slopes. In an attempt to bring together the state of the art capabilities in these fields, as well as new research and developments, the South African Institute of Mining and Metallurgy (SAIMM) in collaboration with the South African National Institute of Rock Engineering (SANIRE) are organising a specialist international symposium on the Stability of Rock

Slopes, to be held in Cape Town in October 2015. Cape Town is considered to be a very appropriate location for the symposium. There is a wide choice of hotels, within a few minutes walk of the symposium venue. In the area there are many steep natural rock slopes, and there are significant hard rock quarries within about an hourʼs drive. Technical site visits to various natural slopes and the quarries will be arranged.

 

Click HERE to read more

The SANIRE Coalfields Branch have the pleasure of hosting the annual SANIRE Symposium on the 11th September 2014 at Glenburn Lodge, Muldersdrift. This symposium has been ECSA approved for one (1) CPD credit.

Click HERE for programme

PFC

 

Dr. Roger Hart will be in South Africa on 18 and 19 September 2014. He has kindly agreed to give two free workshops on Distinct Element Modelling using Itasca's latest Particle Flow Code (PFC). Dr. Hart directed the development of Itasca's six software products, FLAC, FLAC3D, UDEC, 3DEC, PFC2D and PFC3D for more than 20 years and he has conducted over 100 training courses for Itasca software worldwide.

Venue:

Protea Hotel – Fire and Ice! Melrose Arch

22 Whitely Street

Melrose Arch, Melrose

Milan Room

 

Click HERE to read more.

Click HERE for directions

Click HERE for directions street view

 

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The Rock Mechanics Certificate - Paper 1 is a general theoretical Paper covering basic rock mechanics theory application in all types of mining enviroments, surface as well as under ground. To read more click Here.

The SANIRE Coalfields Branch have the pleasure of hosting the annual SANIRE Symposium on the 11th September 2014 at Glenburn Lodge, Muldersdrift. This symposium has been ECSA approved for one (1) CPD credit.

Click Here for programme