Stress measurement specialists since 1987

Well, the past 3 years have been terrible and certainly a period that I'm sure most of us would all like to move on from! Until recently -like many other companies- the last few years have been very difficult for MMS given the COVID pandemic and subsequent travel restrictions associated with it. We had a lot of work lined up, but we were not able to travel to do the work. Fortunately however, borders have now opened up and restrictions have eased... so we are now flat out again!

We are currently working through a backlog of jobs and conducting rock stress measurement tests at various sites world-wide. This year has been a very busy one for MMS.

We do apologise to our many clients who had to wait a number of years for us to be able to get to site to do the work- and we thank you very much for your patience.

We must admit that we have been really slack about updating our news for the last 7 or so years… So we thought we were due for an update! So, here it goes…

Having just completed a successful stress measurement campaign at the Resolution Copper Mine in Arizona just a few months prior, we were approached by Rio Tinto with a request for us to undertake further rock stress testing at Resolution; however, this time round the testing was required down at the bottom level of the mine -known at the time as TPL2- where rock temperatures and water temperatures were in excess of 65°C (150°F)!

While MMS has vast experience in rock stress measurements world-wide -including the use of the original CSIRO HI cell- very little was known about the performance of the HI cell, or for that matter a number of other methods, in these higher temperatures. However, MMS did raise initial concerns regarding the performance of the standard cell in this environment. Rio Tinto commissioned MMS to perform studies on the current CSIRO HI cell at elevated temperatures and to if possible, come up with a design that would be suitable for their application- for a temperature greater than> 75°C (170°F). This was all needed fairly quickly too; as the project where these were to be used (if successful) was due to happen in a few months' time…we needed to get cracking!

MMS decided to work collaboratively with Top Rock Technologies -an Australian manufacturer part owned by the Co-inventor of the original CSIRO HI cell (Rob Walton), amongst other geotechnical instrumentation -for this R&D project in order to develop a High Temperature Hollow inclusion Cell and specific pre-formulated glue mixture.

Due to the urgency of this project, we only had about 3 months to test the performance of the original HI cell and to then come up with something more suitable. However after many hours spent, finally- we got a working system - both HI cell and glue formulation-- to work at the required temperature of 75°C to 80°C.

The standard HI Cell has been successfully used at temperatures of up to 55°C.

However, from our extensive testing we found that after approximately 55°C, the HI cell and the glue used to bond the HI Cell to the pilot hole softens too much. This softening of the glue then does not transmit the strains correctly from the rock and would subsequently lead to erroneous results and so the HI cell in standard guise would not be suitable.

This R&D was all done a few years ago now (back in 2019 to be precise) and all concluded just prior to the start of the COVID pandemic. Unfortunately MMS were not able to get over to do the testing and to trial the newly designed HI cell and glue; however we now know that the standard cell is not suitable in temperatures much above 55°C (130°C), but that we have another system that we can use should the need arise in the future!

Jim had completed the initial testing at the Resolution Copper Mine a few years ago, where he successfully tested at 2 sites. At these sites, the rock temperatures in the upper part of the mine were low. A previous measurement attempt by others had failed. The first test site was extremely shallow -approximately 30m (90') of cover- and very poor ground in the Apache Leal Tuff. It was a good challenge and very good to see the true sensitivity of our testing equipment which enabled us to measure very low strains down to <10 microstrain.

We are also very excited to say that we are now also offering Hydraulic Fracturing rock stress measurement testing again. We recently purchased the system from one of the industries leaders in HF. We have just completed 3 HF sites in the Sydney area for tunnels and freeway extensions. The system worked very well and we have redesigned some of the system to bring it more up-to-date, including developing our own advanced HF software. We are very pleased with the new set-up and reviews from our Clients and the people analysing the data are also very positive.

Jim has been very busy with the overseas work. He has successfully completed testing at Newmont's Subika mine in Ghana, which is the 6th round of measurements undertaken by MMS over there in the past few years. Jim is now currently over working in Utah, USA working at another Rio Tinto underground mine.

After he finishes up in the States, there is a lot of testing to do in Canada, Ghana, and also most likely in Egypt.

Nick and Pete also have to a lot of testing to do and are covering the work in Australia using our own diamond drill rig. List of jobs for them currently include Ernest Henry mine, Mt Isa mines, Telfer, Cosmos Nickel mine, Eloise mine and Dugald River mine.... and the list goes on!

We are still continuously busy with R&D on our diamond drill rig with ways to improve the both safety and ergonomics of our system. We have had remote controls to operate our drill rig for many years now -in order to keep our operators away from entanglement and hydraulic injection injuries- which is something that I have seen being introduced by more rigs these days. It is certainly a change for the better in our opinion.

We are also continuously improving our system for the collection of data from the overcore and biaxial tests. The system we use and have had in place for a little while now allows the data to be sent to a computer and the strain gauge values are returned in real time. Our software also enables plotting of the tests in progress. The data is then stored to the computer (and also to the logger as a backup). The data is automatically stored in our stress programme format and we can have the full 3D stress field result minutes after completing the overcore and biaxial tests. It has proven to be a very robust and beneficial system. For those of you using our stress measurement analysis software, the latest version is STRESS202X- please get in contact if you would like the latest copy.

Now for some older stuff; We have recently completed a large project in Brazil. Currently we are working on a large project at a mine in Tasmania, and prior to that mines in Northern Territory, South Australia, Queensland and Western Australia.

MMS has just completed testing at Newcrest's Cadia East Project in NSW. Prior to our drill and equipment going underground it had to comply with the NSW Department of Mines MDG15 regulations and also satisfy Newcrest's interpretation of these regulations. Two independent audits were undertaken on our drill and equipment. Our equipment passed these audits and is now MDG15 compliant, which means our equipment can be used at any mine in NSW.

We conducted tests at 1 site. We had a good run once our equipment was underground, drilling to depth, overcoring 3 CSIRO HI cells and installing a monitoring cell in 5 days. There will probably be another 2 sites early next year to test as well.

We are off to the Oyu Tolgoi Project in Mongolia this weekend, we have to conduct stress measurement tests and also install monitoring cells.

Early next year we have 2 mines in Western Australia to conduct overcoring tests at, one in South Australia and another one in NSW. There is also a possibility of a large project overseas.

MMS has just released a new version of stress monitoring analysis software for CSIRO HI cells. Multiple stress runs are possible with just a click of a button.

MMS has also just released a new version of stress measurement analysis software (Stress 2011) for CSIRO HI cells. It is now compatible with MS Excel 2007 and 2010. It is also backward compatible with Excel 2003. Soon we will be adding an online software manual in our download section. If you currently hold a Licence for the software and would like an upgrade please email us info@mmsstress.com.au

Last year was very busy and challenging for MMS conducting stress measurement tests. Some sites have been technically challenging with poor core, debonding of gauges from the CSIRO cell, borehole breakout and discing of the core. Some of these sites have been deeper than +1500m and highly stressed. In order to get "good" stress measurement results at some mines we have had to conduct USBM cell overcores as well as using CSIRO HI cells. This USBM cell (2D) does not rely on gluing the gauges to the pilot hole. This information has been invaluable for confirming the results from the HI cells.

We have also been busy modifying our overcore drill rig and developing a heat exchange unit to heat the water for overcore tests (see our FAQ page on the importance of temperature control).

After finishing the Neves Corvo report early last year we have been testing at Ernest Henry Mine, Freeport Indonesia (3 mines 9 sites), Gwalia deeps, Otter-Juan mine and Oyu Tolgoi Project in Mongolia.

This year as well seems likely to be another busy year. With jobs at Oyu Tolgoi again (another 3 sites), Challenger Gold mine, Cliffs Nickel Project and a couple of sites at Ernest Henry mine.