Slope Stability

Keeping Your Mine Site Safe: The Benefits of Slope Stability Radar for Monitoring Mine Walls

As a mining professional, I understand the importance of safety in mining operations. One of the most critical aspects of mining safety is the slope stability of the mine walls.

Instability can lead to accidents, injuries, and even fatalities. Traditional monitoring methods for mine walls can be time-consuming and unreliable, leading to potential hazards and economic losses.

In this blog post, I will introduce slope stability radar (SSR) and its benefits for monitoring mine walls.

Introduction to Slope Stability Radar (SSR)

Slope Stability Radar (SSR) is a remote sensing technology that uses radar waves to detect and monitor changes in the stability of mine walls.

It allows mining companies to detect potential instabilities in mine walls before they become hazards, enabling them to take corrective action before accidents occur. SSR is a non-contact, non-destructive, and non-intrusive technology that can detect changes in the surface of mine walls up to a distance of several hundred meters.

The Importance of Monitoring Mine Walls

Monitoring mine walls is crucial to ensure the safety of mining operations. Mine walls are exposed to various factors that can affect their stability. the factors include weather conditions, blasting, mining activities, and geological conditions.

Instability can lead to rockfalls, landslides, and other hazards that can cause injuries, fatalities, and economic losses. Traditional monitoring methods, such as visual inspections and manual measurements, can be time-consuming and unreliable. And also it is very muc challenging to detect potential instabilities in time.

SSR Benefits for Mining Companies

SSR offers several benefits for monitoring mine walls. Firstly, it allows mining companies to detect potential instabilities in mine walls before they become hazards, enabling them to take corrective action before accidents occur.

Secondly, it provides real-time monitoring of mine walls, allowing companies to respond quickly to any changes in stability. Thirdly, it reduces the need for manual inspections, saving time and resources. Finally, SSR is a cost-effective solution for monitoring mine walls, as it requires fewer personnel and equipment than traditional monitoring methods.

How SSR Works

SSR works by emitting radar waves towards the mine walls and analyzing the reflected waves to detect surface changes.

The SSR system consists of two main components: the radar unit and the data processing unit. The radar unit emits radar waves towards the mine walls and receives the reflected waves. The data processing unit analyzes the reflected waves to detect surface changes and provides real-time monitoring data.

Types of SSR Technology

There are two types of SSR technology: ground-based SSR and airborne SSR. Ground-based SSR is installed on the ground and provides monitoring data for a specific area of the mine wall.

Airborne SSR is mounted on a drone or helicopter and provides monitoring data for a larger area of the mine wall. Both types of SSR technology have their advantages and disadvantages, depending on the specific needs of the mining operation.

Case Studies of Successful SSR Implementation

Several mining companies have successfully implemented SSR for monitoring mine walls. For example, BHP Billiton used SSR to monitor the stability of mine walls in their Olympic Dam mine in Australia.

SSR helped them to detect potential instabilities in time, allowing them to take corrective action and prevent accidents. SSR also reduced the need for manual inspections, saving time and resources.

Another example is Rio Tinto, who used SSR to monitor the stability of mine walls in their Kennecott mine in Utah. SSR helped them to detect potential instabilities and provide real-time monitoring data, enabling them to respond quickly to any changes in stability.

SSR vs Traditional Monitoring Methods

SSR offers several advantages over traditional monitoring methods, such as visual inspections and manual measurements. Traditional monitoring methods can be time-consuming and unreliable, making it challenging to detect potential instabilities in time.

SSR provides real-time monitoring data, enabling mining companies to respond quickly to any changes in stability. Traditional monitoring methods also require more personnel and equipment than SSR, making it a more expensive solution for monitoring mine walls.

Watch this video- https://www.youtube.com/watch?v=C3Dhciv5uBo

Cost-Effective Solutions with SSR

SSR is a cost-effective solution for monitoring mine walls, as it requires fewer personnel and equipment than traditional monitoring methods.

SSR provides real-time monitoring data, reducing the need for manual inspections and saving time and resources. It also allows mining companies to detect potential instabilities in mine walls before they become hazards, enabling them to take corrective action before accidents occur.

Training and Support for SSR Implementation

Implementing SSR requires proper training and support to ensure its effective use. Mining companies need to train their personnel on how to operate and interpret the monitoring data provided by SSR.

They also need to ensure that they have access to technical support to address any issues that may arise during the implementation process.

Conclusion: Why SSR is Essential for Mine Site Safety

In conclusion, SSR is an essential tool for monitoring mine walls and ensuring mine site safety. It provides real-time monitoring data, enabling mining companies to respond quickly to any changes in stability.

It also reduces the need for manual inspections, saving time and resources. SSR is a cost-effective solution for monitoring mine walls, requiring fewer personnel and equipment than traditional monitoring methods.

Implementing SSR requires proper training and support to ensure its effective use. I highly recommend that mining companies consider implementing SSR for monitoring their mine walls to ensure the safety of their operations. You can also read this content- https://waartsy.com/realtime-monitoring-radar-vs-slope-management-plan/

Exploring the Key Factors that Control Slope Stability

As mining experts, we should understand the key factors that affect slope stability and also we should understand the importance of ensuring safe and stable slopes in open-pit mining. Slope stability is a critical aspect of any mining operation, and failure to manage it correctly can result in significant safety hazards, costly downtime, and environmental damage.

In this article, I will explore the key factors affecting slope stability in open-pit mining, from geology and weather to mining equipment and operations.

I will also examine monitoring and evaluation techniques and mitigation methods for slope instability.

Finally, I will discuss future considerations for slope stability in open-pit mining.

Introduction to Slope Stability in Open-Pit Mining

Open-pit mining involves removing rock and soil from the ground to extract valuable minerals. This process typically involves creating large open pits or excavations. This can be several hundred meters deep and several kilometers wide. Slope stability is a critical aspect of open-pit mining, as unstable slopes can lead to landslides, rockfalls, and other hazards. These hazards can endanger workers and damage equipment.

The stability of a slope depends on several factors. The factors includes the geology of the mining site, weather and climate conditions, water management, and mining equipment and operations.

Understanding the Geology of the Mining Site

The geology of the mining site is one of the primary factors affecting slope stability in open-pit mining. The type of rock and soil present at the site plays a critical role in determining the slope’s stability.

For example, some types of rock, such as shale and limestone, are more prone to weathering and erosion than others, such as granite and basalt.

The orientation of the rock layers and the presence of faults and fractures can also affect slope stability.

To assess the geology of a mining site, geologists typically conduct a series of tests and surveys, including geological mapping, rock testing, and geotechnical investigations.

This data is used to develop a detailed understanding of the rock and soil properties and to identify potential hazards, such as unstable rock formations or areas prone to landslides.

Effects of Weather and Climate on Slope Stability

Weather and climate conditions can also have a significant impact on slope stability in open-pit mining.

Heavy rainfall, for example, can increase the amount of water in the soil and rock, making them more prone to erosion and landslides. Extreme temperatures can also cause thermal stress in the rock, leading to cracking and instability.

To manage the effects of weather and climate on slope stability, mining companies typically implement a range of mitigation measures, such as slope drainage systems, erosion control measures, and monitoring programs.

These measures aim to reduce the impact of weather and climate on slope stability and to provide early warning of any potential hazards.

Importance of Water Management in Slope Stability

Water management is a critical factor in slope stability in open-pit mining. Water can weaken the soil and rock, making them more prone to erosion and landslides.

It can also increase the weight of the slope, leading to instability.

Managing water in open-pit mining involves controlling the flow of water through the site, including managing surface water runoff, groundwater, and process water.

To manage water in open-pit mining, mining companies typically implement a range of measures, such as drainage systems, dewatering systems, and water treatment plants.

These measures aim to reduce the amount of water in the soil and rock, preventing erosion and landslides and improving slope stability.

Role of Mining Equipment and Operations in Slope Stability

Mining equipment and operations can also affect slope stability in open-pit mining. Heavy equipment, such as trucks and excavators, can cause vibrations in the ground, leading to cracking and instability.

Overloading of equipment can also increase the weight of the slope, leading to instability. Mining operations, such as blasting and drilling, can also affect slope stability, depending on their location and intensity.

To minimize the impact of mining equipment and operations on slope stability, mining companies typically implement a range of measures, such as limiting the size and weight of equipment, using low-impact drilling and blasting techniques, and monitoring the impact of operations on slope stability.

Monitoring and Evaluation of Slope Stability

Monitoring and evaluation are critical aspects of managing slope stability in open-pit mining.

These monitoring programs aim to detect any changes in slope. The changes can be cracks or movement, while evaluation programs aim to assess the overall stability of the slope.

To monitor and evaluate slope stability, mining companies typically use a range of techniques. These techniques includes visual inspections, geotechnical instrumentation, and remote sensing. The most advanced and latest monitoring technology is realtiem monitoring with ground based radar. Watch this video to know about slope stability radar- https://www.youtube.com/watch?v=C3Dhciv5uBo

These techniques provide real-time data on slope stability. Real-time data enable mining companies to take action to mitigate any potential hazards. Watch this video to know more about slope monitoring- https://waartsy.com/open-pit-and-dump-slope-monitoring/

Mitigation Methods for Slope Instability

Mitigation methods are essential for managing slope instability in open-pit mining. These methods aim to reduce the risk of slope failure and protect workers and equipment.

Some common mitigation methods for slope instability include:

Slope reinforcement: This involves adding additional support to the slope, such as rock bolts or mesh, to increase its stability.

Grading: Slope grading involves reshaping the slope to reduce its steepness and improve its stability.

Drainage: Slope drainage involves installing drainage systems to control the flow of water through the slope and prevent erosion.

Slope monitoring: This involves implementing a monitoring program to detect any changes in slope stability and take action to mitigate any potential hazards.

Case Studies of Slope Stability Issues in Open-Pit Mining

In recent years, several high-profile slope stability issues have occurred in open-pit mining. For example, in 2019, a large landslide occurred at the Chuquicamata copper mine in Chile. Another huge landslide occurred at Bingham Canyon mine of Rio Tinto, causing significant damage to equipment and infrastructure.

In 2020, a similar incident occurred at the Bingham Canyon copper mine in Utah, USA, resulting in the temporary closure of the mine.

These incidents highlight the importance of managing slope stability in open-pit mining and the potential consequences of failing to do so.

They also demonstrate the value of effective monitoring and evaluation programs and mitigation measures in preventing slope instability.

Future Considerations for Slope Stability in Open-Pit Mining

As mining operations continue to expand, the importance of managing slope stability in open-pit mining will only increase.

Advances in technology, such as remote sensing and artificial intelligence, are expected to play an increasingly important role in monitoring and evaluating slope stability. At the same time, there is a growing focus on sustainability in mining, with an emphasis on reducing the environmental impact of mining operations, including managing slope stability.

Conclusion

Slope stability is a critical aspect of open-pit mining, and failure to manage it correctly can result in significant safety hazards, costly downtime, and environmental damage.

Understanding the key factors i.e. geology of the mining site, managing water, mitigating the impact of mining equipment and operations, and implementing effective monitoring and evaluation programs and mitigation measures are all critical for managing slope stability in open-pit mining. By taking a proactive approach to slope stability, mining companies can reduce the risk of slope failure and protect workers and equipment, ensuring the long-term sustainability of their operations

Monitoring of Slope & Instrumentation Methodologies

Introduction

In 2014 I started my career as a geotechnical engineer for a big size open pit metal mine. At that time I didn’t have any idea about managing a hazardous slope. How we can manage the stability of slopes, how we can detect slope failures, how we can detect rock falls, and how we can save man-machineries before a slope failure occurred. But after a few months, I could able to know that already a lot of monitoring instruments were invented which can give us a clear idea about slope behavior. Not only the slope behavior but also those instruments can predict also before a slope collapse.

Mining is an essential part of the modern world. It is a vital industry that provides the raw materials for many essential products and contributes significantly to the global economy. However, mining also presents significant risks, particularly in terms of safety, environmental impacts, and economic efficiency. One of the critical challenges in mining is the management of mine pits and dump slopes. These areas are prone to slope failures, which can have devastating consequences, including loss of life, property damage, and environmental degradation.

To manage these risks, mines use various instrumentation methodologies, and data analysis techniques to assess the stability of slopes and detect potential failures before they occur. In this article, we will explore the instrumentation, monitoring, and data analysis methods used in mine pits and dump slopes.

Instrumentation

Instrumentation is an essential component of slope stability analysis in mining. It involves the use of various tools and techniques to measure critical parameters that affect the stability of slopes. These parameters may include slope angle, rock mass properties, water pressure, and seismic activity.

Open pit and dump slope monitoring is a critical aspect of mining operations, as it helps to ensure the safety of workers and equipment, as well as the environment. This article will discuss the importance of open pit and dump slope monitoring and the types of monitoring systems commonly used in mining operations.

Importance of Open Pit and Dump Slope Monitoring

Open pit and dump slope monitoring is essential for several reasons. First and foremost, it helps to prevent accidents and injuries by identifying potential hazards before they cause harm. Slope failures, rockfalls, and landslides can all pose significant risks to workers and equipment in mining operations, and monitoring systems can help to identify these hazards early on so that appropriate action can be taken.

In addition, open pit and dump slope monitoring can help to optimize mining operations by providing data on factors such as ground stability, equipment performance, and environmental conditions. This data can be used to make informed decisions about how to mine the deposit most efficiently and safely.

Types of Open Pit and Dump Slope Monitoring Systems

There are several types of open pit and dump slope monitoring systems used in mining operations. Some of the most common systems include:

Direct method

Radar Monitoring Systems: Radar monitoring systems use radar technology to detect movement in the pit and dump slope. These systems can detect small changes in the slope and provide early warning of potential slope failures or rockfalls. Radar monitoring systems are particularly useful in areas where ground movement is difficult to detect with other types of monitoring systems. You should read the following article on radar https://waartsy.com/realtime-monitoring-radar-vs-slope-management-plan/
Inclinometer Monitoring Systems: Inclinometer monitoring systems use sensors to measure the slope angle and deformation. These systems can detect changes in the slope angle or deformation, which can indicate potential slope failures. Inclinometer monitoring systems are commonly used in areas where the slope angle is steep and unstable.
Extensometers: Extensometers are used to measure the deformation of the rock mass surrounding an open pit mine. These instruments consist of two anchor points that are fixed in the rock mass, and a movable probe that is attached to these anchors. As the rock mass deforms, the probe moves, and the extensometer measures the distance between the two anchor points.
Strain Gauges: Strain gauges are used to measure the stress and strain on the rock mass in an open pit mine. These instruments consist of a thin wire or foil that is attached to the surface of the rock mass. As the rock mass deforms, the wire or foil stretches or compresses, and the strain gauge measures the resulting change in electrical resistance.

Indirect Method

Ground Penetrating Radar (GPR): GPR is a geophysical instrument that uses electromagnetic radiation to detect changes in the subsurface. GPR can detect changes in the composition of the rock mass. The presence of voids or fractures, and other features that can affect the stability of the slope.
Seismometers: Seismometers are used to measure ground motion and vibrations in an open pit mine. These instruments can detect even small vibrations caused by blasting, equipment operation, or ground movement. Seismometers can be used to detect potential slope failures. It also used to monitor the effects of mining activities on the surrounding environment.
Global Navigation Satellite Systems (GNSS): GNSS is a positioning system that uses satellite signals to determine the location of equipment and structures. GNSS can be used to monitor the movement to measure changes in the position of structures or geological features
Geotechnical Monitoring Systems: This systems use a range of sensors, including inclinometers, extensometers, and strain gauges. It is used to measure ground movement, deformation, and stress. These systems can provide data on ground stability and help to identify potential hazards such as slope failures.
Environmental Monitoring Systems: Environmental monitoring systems measure factors such as temperature, humidity, and gas concentration in the pit and dump slope. It will give an idea about the amount of deviation that can occur during deformation monitoring through instruments.
Water Monitoring Systems: Water monitoring systems measure water levels, flow rates, and water quality in the pit and dump slope. Take look on the video on live monitoring through slope stability radar https://www.youtube.com/watch?v=C3Dhciv5uBo

Conclusion

Open pit and dump slope monitoring is a critical aspect of mining operations. Monitoring systems can help to identify potential hazards and optimize mining operations by providing data on ground stability. There are several types of monitoring systems used in mining operations, including radar, inclinometer, geotechnical, environmental, and water monitoring systems. Investing in open pit and dump slope monitoring, and also mining companies can help to ensure the safety of workers and equipment. Not only the safety of man machinery but also it can optimize the operational parameters.

Safe Work Practices near a hazardous slope

Any steep slope and other types of terrain may be hazardous and have the potential to greatly impact the safety of personnel and equipment, as well as, quality and production if not appropriately identified, evaluated and addressed. Proper Hazard identification and Risk Analysis is required to address slope instability hazards by authorized person (i.e. Geo-technical Engineer, Safety Officer and Mine Manager) but safe work practices have to be implemented in each and every case by every individual as per the instructions mentioned below.

Instructions:

1. All individuals shall take direction from the shift in-charge or area in-charge of the task being conducted near a hazardous slope.
2. Anticipate duration of exposure, the nature of the tasks to be performed and equipment to be used. remain alert and attentive to the surroundings at all times
3. Assess the slope conditions contributing to potentially hazard.
4. Determine locations, gradients, lengths, and other relevant conditions of the designated area and determine access requirements and assess the escape route during any emergency in the designated area.
5. Be aware of rolling boulders or loose rocks beneath the designated slope. Ensure warning signs are in place if required.
6. Ensure you are not in the impact/projected zone of mass/boulder that can slide/fall. At the same time ensure you are in view of operators of equipments at all times.
7. Do not park any LMV in the line of fire of mass/ hanging boulder that is prone to slide/fall. LMV should be parked in nearby identified safe zone
8. Refuse to perform work when unsafe conditions have not been properly addressed.
9. Refuse to perform work if you do not have confidence to work near any hazardous slope.
10. Report potential hazards to shift in-charge or the designated Person-in-Charge of the task. Ensure you are acquainted with response procedure during any emergency.
11. Operators must always use seat belts when operating equipment and vehicles.
12. Ensure you wear appropriate PPE
13. Visitors are required to follow instructions provided at the orientation and remain alert and attentive to their surroundings at all times.
14. Avoid placing vehicles in the line of fire of materials and/or equipment and report any apparent safety concerns or potentially hazardous situations IMMEDIATELY to site supervisor or area in-charge or shift in-charge.

Machine-wise instructions:

Dozer operation
1. Do not deploy dozers on steep slope or in the line of fire of mass/ hanging boulder. For mild slope (i.e. hill top) avoid traveling across slopes as much as practical.
2. Keep the dozer blade as close to the ground as possible while travelling up or down a slope.
3. If the machine starts to slide sideways when working across a slope, turn the machine downhill and drop the blade.
4. Debris and loose rocks along dozer breaks should be stabilized before personnel are allowed to work below them. 5. When parking a dozer, the blade should be placed on the ground.

Excavator operation
1. Do not deploy any excavator on steep slope or in the line of fire of mass/ hanging boulder. For mild slope (i.e. hill top) create a level area where Excavators are excavating along slope areas.
2. Where turning is unavoidable, or where ascending or descending, turn as gradually as possible to maintain stability.
3. For uphill travel, extend the boom and half full bucket forward and for downhill travel bring the boom and empty bucket in close, to maximize stability and traction.
4. When descending a slope, use the same (low) gear range required to climb it.
5. When parking an excavator, the bucket should be placed on the ground.

Front-end Loaders
1. Do not deploy any excavator on steep slope or in the line of fire of mass/ hanging boulder.
2. Do not create an undercut at the toe of a slope in any condition
3. While performing Turra coal excavation- keep safe distance from overhang or hanging boulder on Dragline highwall
4. Dress the highwall properly and achieve clean highwall as much as possible. But always ensure 2m coal berm is there at the Turra roof.
5. Do not create undercut at the dragline dump side.

Trench Excavation
1. Before any trenching operation barricade the area properly. Distance of barricading from the trench line should be at least 1.5 times of the trench depth.
2. The slope of the trench walls should be decreased if the ground condition is poor/ soft.
3. When excavating deep trenches by sitting inside the trench, large rocks may be encountered that have a possibility of rolling down. The following protective methods/measures should be implemented to mitigate the risks associated with falling rocksThe Excavator Operator will create a benched platform from the spoil materials from the trench to set the large rock on. This will create a stable surface for the boulder to sit on, reducing the possibility of the rock moving down the hill. Additional spoil material should be positioned around the rock to provide support. If the boulder is very large, it should be transported to the top of the platform by the excavator.
4. Spotters should be positioned in safe zones near the excavation and equipped with safety air horns to pause work if unsafe conditions exist (e.g., a large rock being dislodged and descending the hill).
You can go to other posts in this plat form www.waartsy.com for better understanding on slope stability. Read post page in this site.

What is important- Radar or Slope Management Plan?

In the last few decades, a good number of deformation monitoring instruments have been introduced for open pit slope, mainly to measure the spatial distribution of slope movement over time which is the main analysis factor for a geotechnical engineer. The range of accuracy varies from a few centimeters to less than a millimeter for those deformation monitoring instruments. Obviously, accuracy plays a major role in deformation analysis but ‘accuracy’ will have no meaning if mine management does not develop a proper strategy for an early warning system to detect the time of failure (TOF). Pre and post-installation strategies will actually define the strength of a geotechnical cell in a mine. The strategy before procurement of instrument for specific applicability and the strategy after installation of a monitoring instrument to detect slope behavior and the emergency plan in terms of Trigger Action Response Plan (TARP) are the main tools to manage risks of unexpected slope instabilities in open pit mine. This article presents will give us an idea about the importance of slope management plan, monitoring instrument, and monitoring protocol. And also we will know what is most important out of these three things to determine the Time of Failure and to save man-machinery.

Keywords: Ground-Based Radar, Slope Management Plan(SMP), Real-time deformation, Time of Failure (TOF), Inverse velocity, Trigger Action Response Plan (TARP)

INTRODUCTION

The risk management for personnel, equipment, and production regarding slope instability is one of the most important roles for mining engineers. Both for metal mines and coal mines- the risk mechanisms are the same but the scenarios are different because of the geometry, rock structure, and the differences in ultimate working depth and ultimate pit angle. The interesting fact is that if all these factors remain the same for two different mines then also the amount of deformation before collapsing will vary in a long-range because of the difference in intrinsic properties of different rock types. If intrinsic properties remain the same then also the deformation limit may vary because of the difference in time of exposure and external effects on different slope geometries.

A lot of data collection, data analysis, experience for a particular site, and ultimately the strategy-making can help a geotechnical engineer to develop a protocol for that particular site for the prediction of slope behavior. One side the strategy to know slope behavior and another side Trigger Action Response Plan (TARP) will make a complete package of slope management plan.

The common questions of mine management to establish a methodology should be—

How much total cumulative deformation is acceptable for a particular slope?
How much rate of deformation is acceptable and for how much time?
What should be our geotechnical alarm limit and what should be our critical alarm limit?
Which instrument should we consider for TARP?
What type of noise should we filter and what type of trend is acceptable?
What should be our strategy to stop and resume operation?

What are the factors that we need to consider for developing the protocol for slope monitoring—

Site applicability of different deformation monitoring instrument
Man and machinery exposure limit
Accessibility of the site for installation of monitoring device
Young modulus of the rock type
Brittleness/ ductileness of the rock-
Orientation of joints and other structures
Geometry of the slopes
Time of slope exposure

WRONG CONCEPTS

Before going to the methodology to develop the protocol for early warning system we need to cross the boundaries which can trail us towards confusion. Those boundaries are actually some wrong concepts which are forcing miners not to implement geotechnical instrumentations for slope stability; across the country. The wrong concepts are—

Accuracy is the ultimate factor regarding selection of monitoring instrument
Conventional method of monitoring and other monitoring system is not required if we install ground based radar
Cost of radar is very high
Mine Management can be in relaxed mood because radar will detect and predict failure
Always inverse velocity method will be applicable to determine TOF
Geo-technical slope failure and slope collapse is same
Radar will always give accurate deformation data
FLOWCHART TO MANAGE A SLOPE : The methodology for developing protocol of slope monitoring, early warning system and time of failure prediction can be summarized stepwise (Figure 1) as mentioned below—

Figure 1: Flowchart for strategy and potocol developnent for early warning system

4.0 What is early warning system and how to link it with TARP?

Early warning system is nothing but an alarming system in emergency situation. Now-a-days almost all hi-tech monitoring instruments are providing the alarming system after crossing the threshold limit decided by geo-tech engineer. All ground based radars have alarming system, all the laser scan based instruments are also proving alarming system, three dimensional based LiDAR, TDR, Micro seismic method and even the robotic total stations are also providing early warning system in alarming method to alert people regarding emergency situation.

For Trigger Action Response Plan (TARP), different conditions and limits of SSR data has to be defined. Triggering points in terms of rate of deformation and number of scans is to be mentioned in the TARP document.

Different alarm can be fixed as triggering events (Figure 8) in TARP, for different range of deformation (Figure 9). Generally geo-tech engineer should 2 or 3 different alarm according to the seriousness of the rate of deformation amount.

Example of Different alarms of Monitoring instruments

An example of specific TARP for mine premises

From the above-mentioned theories, we can easily conclude that prediction of time of failure and proper TARP implementation is not that much easy process. Obviously suitable instrument i.e. Ground based Radars makes the Geotech engineers’ life very easy in predicting the slope behavior but considering the shape and size of a mine, every time it may not be possible to manage all the slopes of a mine by using a single Radar. This instrument has enormous power and capacity to save man-machinery but without a proper monitoring protocol and proper TARP, it is not possible to save man and machinery by evacuating them from the critical area. And without making a slope management plan, by implementing only the radar technology, we can not manage every slope of our mine. Somewhere we need only conventional monitoring instrument, somewhere we need line of site monitoring instrument, some where we need 3d monitoring instrument. These are completely dependent on the site specific requirement and confidence of site geotechnical engineer. It’s not like that- we have installed radar and it will save our man-machinery. There are more than 5 pillars in the slope management plan, i.e. Numerical simulation, monitoring & data analysis, operational measures, slope stabilization, and trigger Action response plan (TARP) including training etc. In recent trends-in India, people are talking about monitoring pillar only out of those 5 pillars. And Radar is only one part of this 2^nd pillar (monitoring) which covers below 30% of the 2^nd pillar only. Hence we can understand slope management plan is a huge thing that is much more important than a particular instrument. If slope management plan is robust that it can cover everything which we need.

Five Things you should know about slope stability

Special Thanks to Dr Loren J Lorig

Modern-day mining requires the optimization of pit slopes to ensure that the slopes are stable and economic to mine. While several methods are available to help design and monitor the stability of the slopes, there are five major aspects that geotechnical engineers should know when they are involved in slope stability studies. The collection of appropriate data from the project site and the challenges of sampling bias, the problems of using average values in the design of excavations, the impacts of extreme natural events on ground stability, the importance of design validation, and the future trends in slope design, analysis, and monitoring for enhanced security of personnel and resources are presented here.

Characterization: why should we focus on the weakest materials and how does sampling bias work against us
Data analysis: Why it is wrong to use average values in design.
Design analysis: what are the impacts of extreme events (earthquakes and rainfall) on slope stability
Design validation: why design validation is essential
Future trends: how slope swill be studies in the future
Characterization: In this pillar- a geotechnical engineer has to determine the values of RMR, Q value, GSI, more coulomb, and Hoek- Brown parameters (detail definition and significance of each parameter has been described in a different post on this site www.waartsy.com). But every engineer should know to choose the sample rock type. The section should not be the best rock. The focus should be on the weakest parts of the rock mass. By focusing on deterministic analysis and stochastic analysis- proper values of Cohesion ( c) and Փ (angle of internal friction) only give accurate output while simulating a particular geometry otherwise the output can be anything that can lead to an unsafe design.
Data Analysis: Well, here we can take a real-life example. Suppose one day you have loose motion and the next day after taking medicine you are suffering from constipation. So, if we take the average of your stomach problem then the first day it is ‘-100’ because of loose motion, and the next day the value is ‘+100’ because of constipation. Hence the average is ‘0”. So you are completely OK with your stomach. You neither have loose motion nor have constipation.

Exactly the same thing is applicable for rock mass also. You can not take the average. This is the problem of average value.

Rock mass variability can significantly reduce Factor of Safety (FOS) and increase Probability of Failure (POF)”. Hence our consideration within the rock mass variability is very much valuable to determine FOS and POF.

Design Analysis: obviously every miner thinks about the perfect design to bring optimum production and optimum stability on a single page. But there are only a few engineers who think about the extreme events which can affect the design. Yes, that is the right way to analyze a design. The effects of extreme events have to be considered. Earthquake or similar big events has to be incorporated into large-scale designs. Seismic effects, heavy rainfall, dynamic mining all these things have to be incorporated.
Design Validation: all designs are based on assumptions that must be confirmed for the design to be valid.

Example of reinforced concrete- concrete must be tested and shown to exceed required strength in order to validate the design.

For open-pit mines, we need to validate assumptions: rock quality and strength, structural setting (rock fabrics, faults, etc); water levels.

Future Trends: Machine learning and artificial intelligence have grown quickly in the last 5-6 years and have demonstrated success in some application areas, ML and AI are effective in data-rich environments where the governing equations are unknown. In geomechanics, we are a data-poor environment and the governing equations are unknown. In this regime numerical modeling is effective.

A few bigger fatal incidents due to slope failure

It is important to note that mining incidents are tragic and sensitive events, and it is not appropriate to rank them or use them for any other purpose than learning from the mistakes made to prevent future incidents. Here are 10 examples of fatal incidents due to slope failure in mines:

Grasberg Mine, Indonesia – In 2017, a slope failure caused a massive landslide that buried 38 workers under tons of debris. Unfortunately, 13 workers were killed in the incident.
Rajmahal OC mine, India – In, 2016, a slope failure caused a massive dump and landslide that buried 23 workers under tons of debris. Unfortunately, all 23 workers were killed in the incident.
Sasa Mine, North Macedonia – In 2019, a landslide occurred in the waste rock dump area of the mine, burying four workers. All four workers were killed in the incident.
Mount Polley Mine, Canada – In 2014, a tailings dam at the mine failed, causing a massive landslide that destroyed several homes and contaminated nearby waterways. Fortunately, there were no fatalities, but the incident caused significant environmental damage.
Ojuela Mine, Mexico – In 2014, a landslide occurred at the mine, burying several workers. Unfortunately, five workers were killed in the incident.
Tavsanli Mine, Turkey – In 2010, a landslide occurred at the mine, burying several workers. Tragically, 30 workers were killed in the incident.
Chilean Mine, Chile – In 2010, a landslide occurred at the mine, trapping 33 miners underground for 69 days. Fortunately, all of the miners were rescued, but the incident highlighted the dangers of slope instability in mining operations.
Doe Run Mine, Peru – In 2012, a landslide occurred at the mine, burying several workers. Unfortunately, three workers were killed in the incident.
Sarshatali Mine, India – In 2009, a slope failure occurred at the mine, burying several workers. Tragically, seven workers were killed in the incident.
Cadia Mine, Australia – In 2019, a tailings dam at the mine failed, causing a landslide that buried several vehicles and caused significant damage to the mine infrastructure. Fortunately, there were no fatalities.
Bingham Canyon Mine, USA – In 2013, a landslide occurred at the mine, causing significant damage to the mine infrastructure. Fortunately, there were no fatalities.

It is important to note that each of these incidents was caused by a combination of factors, and it is crucial for mining companies to prioritize slope stability monitoring and implement best practices for slope design and management to prevent future incidents.

25 checkpoints for assessing slope stability in an open cast mine:

Conduct a thorough site investigation and geological study to understand the terrain and rock formations in the area.
Identify the slope characteristics such as slope angle, height, and orientation.
Assess the water table and water flow in the area to identify potential destabilization factors.
Evaluate the potential impact of mining activities on the slope stability, including blasting and excavation.
Determine the rock mass properties and classify the slope according to the Rock Mass Rating (RMR) system.
Conduct a detailed survey of the slope to identify any surface features that could indicate instability.
Monitor the slope over time to track any changes or movement.
Use geotechnical instrumentation to measure slope movements, including inclinometers, extensometers, and piezometers.
Install groundwater monitoring wells to track changes in water levels.
Conduct laboratory tests on rock samples to determine their strength properties.
Identify the presence of faults or other geologic structures that could affect slope stability.
Evaluate the impact of seismic activity on slope stability.
Consider the impact of weathering and erosion on the slope stability.
Conduct a stability analysis using appropriate software or analytical methods.
Evaluate the slope stability under different conditions, such as peak rainfall or extreme weather events.
Determine the potential failure modes of the slope, such as plane, wedge, or toppling failures.
Evaluate the factor of safety of the slope, including both static and dynamic factors.
Consider the potential consequences of slope failure, such as damage to equipment or personnel injuries.
Develop a slope management plan that includes monitoring, maintenance, and emergency response procedures.
Implement slope stabilization measures such as slope drainage, benching, and shotcrete.
Consider the use of rock bolts, soil nails, or other reinforcement techniques to improve slope stability.
Evaluate the effectiveness of the slope stabilization measures over time.
Consider the potential impact of climate change on slope stability.
Train personnel on slope stability and emergency response procedures.
Regularly review and update the slope stability assessment and management plan as necessary.

Note that this checklist is not comprehensive and that each open cast mine may have unique factors to consider. It’s important to consult with experienced geotechnical engineers and other professionals to ensure a thorough assessment of slope stability.

How a Geotechnical engineer confirms the stability of a slope through Numerical simulation

Area identification

As per the requirement of the ABP target and approved mine scheme, areas are to be decided by the mine planning engineer where mining excavation will be done in near future. It can be in bench-scale, inter-ramp scale or large scale. That identified area is to be approved by a mine planning engineer.

2. Rock/ rockmass/ properties and collection of other inputs

After identifying the area, all rock properties data from already been tested from the laboratory to be gathered. The field observational data, geometrical data and all geological data i.e compressive strength, tensile strength, shear strength, cohesion, poison’s ratio, young modulus and other rock/ site-specific constants, which are needed for numerical modelling need to be gathered.

3. Structural modelling

All structural data i.e. joint properties, fault/fold/dyke attributes and shear zone related data to be collected as an input for numerical modelling. Hydrogeological data is also to be recorded. RMR, mRMR, RQD, GSI and other geotechnical data are also required for numerical simulation.

4. Pit design/ dump design

Either the mine planning engineer will provide the pit design in Dxf format or the Geotech engineer will design pits in planning software. These pit/dump design geometries will be the main input for the numerical simulation.

5. Numerical modelling and FOS determination

Considering all the geological, geometrical and other mining parameters, numerical modelling shall be done in a number of iterations to determine the Factor of safety in each concerned section. For numerical modelling, any readily available method (BEM/FEM/DEM) in either 2D or 3D can be used.

6. Analysis of the numerical model result

Geotech engineer will analyze all the results of numerical simulation determined by the modelling software. Those shall be discussed with the mine manager, production engineers and mine management for their acceptance. Displacement analysis, damage analysis and stress analysis shall also be analyzed by geotechnical engineers ad planning engineers.

7. Aligning the design with govt/ statutory guidelines

Not only the acceptance of mine management but also the designs will be aligned with all the statutory guidelines (i.e DGMS, IBM, MoEF, PCB etc)

8. Re-interpretation and redesign of pit and dump

If the numerical simulation result is OK and accepted by the mine management then those designs shall be released for fiel implementation but those are not OK, then again reiteration shall be done considering different input parameters.

9. Finalization of pit design/ dump design

If all the output results seem OK, then those designs shall be released to the production dept for field implementation.

RESOURCES REQUIREMENT:

A trained Geotechnical engineer (Mining engg/ geologist or Civil engg)
Trained mining engineer in mine planning software
High configuration desktop/laptop system (at least 32GB RAM)
Mine planning software (SURPAC/ Data mine/ Vulcan or similar software)
Numerical modelling software (FLAC/MAP/Phase/UDEC/3DEC/Plaxis/Galena/Slide or similar software)

Five Things you should know about slope stability

Special Thanks to Dr Loren J Lorig

Characterization: why should we focus on the weakest materials and how does sampling bias work against us
Data analysis: Why it is wrong to use average values in design.
Design analysis: what are the impacts of extreme events (earthquakes and rainfall) on slope stability
Design validation: why design validation is essential
Future trends: how slope swill be studies in the future

Characterization: In this pillar- a geotechnical engineer has to determine the values of RMR, Q value, GSI, more coulomb, and Hoek- Brown parameters (detail definition and significance of each parameter has been described in a different post on this site www.waartsy.com). But every engineer should know to choose the sample rock type. The section should not be the best rock. The focus should be on the weakest parts of the rock mass. By focusing on deterministic analysis and stochastic analysis- proper values of Cohesion ( c) and Փ (angle of internal friction) only give accurate output while simulating a particular geometry otherwise the output can be anything that can lead to an unsafe design.

Data Analysis: Well, here we can take a real-life example. Suppose one day you have loose motion and the next day after taking medicine you are suffering from constipation. So, if we take the average of your stomach problem then the first day it is ‘-100’ because of loose motion, and the next day the value is ‘+100’ because of constipation. Hence the average is ‘0”. So you are completely OK with your stomach. You neither have loose motion nor have constipation.

Exactly the same thing is applicable for rock mass also. You can not take the average. This is the problem of average value.

Design Analysis: obviously every miner thinks about the perfect design to bring optimum production and optimum stability on a single page. But there are only a few engineers who think about the extreme events which can affect the design. Yes, that is the right way to analyze a design. The effects of extreme events have to be considered. Earthquake or similar big events has to be incorporated into large-scale designs. Seismic effects, heavy rainfall, dynamic mining all these things have to be incorporated.
Design Validation: all designs are based on assumptions that must be confirmed for the design to be valid.

Example of reinforced concrete- concrete must be tested and shown to exceed required strength in order to validate the design.

For open-pit mines, we need to validate assumptions: rock quality and strength, structural setting (rock fabrics, faults, etc); water levels.

Future Trends: Machine learning and artificial intelligence have grown quickly in the last 5-6 years and have demonstrated success in some application areas, ML and AI are effective in data-rich environments where the governing equations are unknown. In geomechanics, we are a data-poor environment and the governing equations are unknown. In this regime numerical modeling is effective.