SLOPE STABILITY MONITORING
A safe pair of eyes
With high profile open pit wall failures and tailings dam collapses in the past decade , ultra high accuracy predictive slope stability monitoring is no longer deemed a luxury – it is a necessity . Paul Moore delves into the market
Slope stability monitoring is often perceived to be mainly about the instruments such as radars that are deployed on the edge of open pit mines or tailings dams – but the interpretation of the data is just as important as the hardware – and the largest players also offer remote monitoring services using their own inhouse geotechincal engineering teams .
IM Editorial Director Paul Moore recently visited with slope stability monitoring experts GroundProbe at its remote monitoring hub in Santiago , Chile – one of three global bases for its Geotechnical Support Service ( GSS ) offering .
To give some background , Orica acquired GroundProbe in early 2018 for A $ 205 million , bringing one of the world ’ s leading radar and laser-based slope stability monitoring system providers together with the global leader in mining explosives and advanced blasting services .
At that time GroundProbe had one active Geotechnical Support Service ( GSS ) monitoring centre in Balikpapan , Indonesia which opened in 2015 . It was serving the Asia-Pacific , African and North American markets . It has continually expanded since its opening . But there was no GSS hub for Latin America – so GroundProbe went on to open a monitoring centre in Santiago , Chile in 2019 , within Orica ’ s main Chile office , equipped initially with four monitoring stations . This was followed by another in Belo Horizonte , Brazil in 2021 with five monitoring stations , plus additionally in Brazil there are also a number of on-site monitoring stations related to tailings and hard rock mines . Now , GSS is globally staffed by over 130 engineers .
The two centres in Chile and Brazil provide
24 / 7 real-time radar and laser monitoring services for tailings dams and mines throughout Spanish and Portuguese speaking countries in South America as well as Mexico and Central America .
On the opening of the 2019 centre in Santiago , Orica President Latin America and Group Executive Brian Gillespie commented to IM : “ I really saw that there was a huge opportunity not only for remote monitoring services in South America but also to offer them with Spanish speaking geotechnical support engineers . Plus , I wanted it to be within the Orica offices in Santiago because many of the major Orica customers either already were GroundProbe technology users or subsequently became users .”
GroundProbe SSR-XT at Gold Fields ’ Salares Norte site in the Atacama region , Chile
Each of the geotechnical support engineers can monitor multiple separate mine walls or tailings dams – where each is being actively monitored by one GroundProbe radar system - whether that be broad-area monitoring solutions for example with the SSR-Omni and SSR-FX ; or more tactical , targeted monitoring for example with the SSR-XT . These are all capable of submillimetre movement detection , in the case of the SSR-Omni from up to 5.6 km away . The engineers also monitor GroundProbe ’ s laser fleet and thirdparty devices and provide short and long term reporting services .
On average , GroundProbe worldwide will identify and communicate the onset of slope instability for one customer every two days . In total , the GSS team has now detected and communicated the onset of over 5,000 collapses at customer sites . Gillespie : “ There is sometimes a misunderstanding that wall collapses are instantaneous as that ’ s when the human eye sees the failure – but it is always preceded by an initially slow but accelerating period of deformation for weeks or even months . It is the accelerations that we are mainly looking for .”
So what is the role of the engineers in the GroundProbe facility and how do they interact with the customer ? Fundamentally you have the SSR itself which is a highly specialised technical tool to predict and determine mine or tailings wall deformation or collapse . And even if the mine has some of its own geotechs , which most do , in a mine that needs close around-the-clock attention in certain areas , GSS means having an independent second line of defence if you like – and often GroundProbe has additional insights . Paulo Aguilera , Business Manager LATAM at GroundProbe : “ If you have one wall that you think is potentially fragile – for you to monitor that yourself 24 / 7 means the mine having to
RIEGL ' s Monitoring Apps
LiDAR-based slope stability scanner major RIEGL ’ s already well established bundle of Mining Apps
( Monitoring App , DesignCompare App , SlopeAngle App ) introduced in 2021 have been extended by the Monitor + App with the new bundle of four apps referred to simply as RIEGL Monitoring Apps .
Thomas Gaisecker , RIEGL Senior Manager , International Sales , says the new Monitor + App is a solution not only for permanent monitoring , but also for periodic and sporadic monitoring . The app allows you to now also interrupt the monitoring schedule and use the scanner temporarily for other surveying purposes . Once the scanner is returned and mounted on almost the same position the monitoring can be continued . The app automatically aligns the new position to the data acquired earlier , so that correct change detection is guaranteed .
Furthermore , the new Monitor + App supports also automatic prism monitoring on a defined schedule . This means that the Monitor + App can do the work of traditional prism monitoring , how it
is already realised by robotic total station , but furthermore offers all the advantages of complete surface monitoring .
Finally , for 24 / 7 operation and full remote operation of its laser scanners , RIEGL has introduced the RIEGL V-Line CB23 communication box .
22 International Mining | AUGUST 2023