What is advanced numerical modelling and why is it relevant to the mining industry?

Advanced numerical modelling is reasonably new to the mining industry. Currently, it is being implemented spasmodically in the geotechnical engineering field to assist in mine design, mine planning and geotechnical design. Numerical modelling can help mining companies and consultants to predict rock mass behaviour, understand and predict rock damage, and appreciate the interactions between neighbouring pieces of development. Advanced modelling techniques have been used to improve mine performance through optimising various aspects of an underground mine such as pillar and stope sizes, mining sequence and controlling dilution and mining induced seismicity. These modelling analyses are generally inexpensive relative to the financial benefits that they bring to a mine. However, numerical modelling is often considered ‘too difficult’ or ‘time consuming’ and is therefore generally left to specialist consultants with many years of modelling experience. This created the impetus for StopeX.

What is StopeX?

StopeX was primarily developed as a plug-in software to FLAC3D which helps to lessen difficulty and decrease time taken in numerical modelling for beginner to intermediate users. StopeX uses ordinary, and often readily available, mine geometries (stope shapes, development solids, topographies, historical mining, and backfill) to create a FLAC3D model for the user. StopeX includes provisions for in-situ stress conditions, FLAC3D solving parameters, meshing preferences and up to 10 isotropic or anisotropic rock mass domains.

Why use StopeX? What are the advantages of using StopeX?

StopeX boasts a very sleek and easy-to-navigate user interface with real time helps. The primary advantage of using StopeX over using unsupported FLAC3D, or any other numerical modelling package, is that model construction time is generally reduced from 20 – 100 hours to 0.5 – 2 hours. StopeX also uses the built-in material model IUCM, a unique and accurate material model developed by Cavroc. This model was implemented to be detailed and versatile and has been calibrated and verified with over 100 mining cases worldwide. This means that, using StopeX, every geotechnical engineer can create accurate, bug-free models in little to no time.

What is the IUCM?

The Improved Unified Constitutive Model (IUCM) was developed by Cavroc and serves as the built-in material model for StopeX. The IUCM is applicable to a wide range of ground conditions and failure mechanisms while still being simple to understand. Detailed information is available in the IUCM section

What are Octree Meshing Parameters?

Octree meshing parameters are user instructions to FLAC3D on how the model mesh should be constructed. These parameters detail how many zones the model should contain (target number of zones), maximum zone size (far field zone size), and the generally desired zone size (required zone size). The aforementioned parameters are global octree meshing parameters and will be applied as a base-level estimate to the entire model. Each input geometry can then be assigned specific octree meshing parameters. These local octree meshing parameters include the target minimum zone size for that geometry (minimum zone size) and the distance from that object to which the required zone size should be applied (zone densification distance). Note that if StopeX cannot comply with the user requests, a prompt will appear in FLAC3D interface which suggests that the target number of zones be changed. If this prompt appears it is advisable to change the target to the StopeX suggestions.

What does ‘Relative Geometrical Accuracy’ mean?

StopeX will attempt to localise zones (elements) based on a user’s geometries for stopes, development, area of interest or historical mining. Any (or all) of these imported geometries can be assigned a desired zone size and a relative geometrical accuracy. The relative geometrical accuracy can be assigned as minimum, maximum or intermediate. FLAC3D will place more emphasis on obeying user desired zone size on those areas with maximum geometrical accuracy relative to those areas set to intermediate or minimum. In a practical sense, the most crucial areas of a user’s model should be set to maximum geometrical accuracy and those less critical areas should be set to intermediate or minimum.

Should I use .dxf or .stl file format with StopeX?

Most CAD packages can easily export both .dxf and .stl files. StopeX functions properly regardless of the drawing file import. However, Cavroc generally recommends to use stereolithography (.stl) files as opposed to drawing exchange format (.dxf) owing to the consistent nature of .stl files. Stereolithographies are simple surface files which do not possess extraneous properties (for example colour), which a .dxf might. This means that .stl files do not have the chance of compatibility issues that .dxf files could. For this reason .stl files are more transferrable between software than .dxf files.