Why Geometry Comes First in Underground Mining Optimization

Geometry as the Foundation of Underground Optimization

Geometry sits at the core of underground mine design because it directly dictates the viable mining method. A narrow, steep vein naturally pushes the operation toward mechanized cut and fill or narrow long-hole stoping where angle tolerances, minimum mining width, and stope alignment must stay within strict limits. In contrast, gently dipping stratiform deposits typically lead to room-and-pillar layouts that begin with a grid structure before selecting profitable cells for early phases. For massive ore bodies with sufficient rock strength, sublevel stoping and related large-scale methods become more efficient, allowing solvers to smooth stope outlines and reduce unnecessary extractions.

Why Method Selection Depends on Geometry

If the orebody type, dip, thickness, and allowable orientations are not locked in early, optimizers end up producing shapes that cannot be mined without heavy rework. Designers then need to slice, trim, or fully restructure the generated stopes to fit the actual method. Geometry defines the operational window, keeps the model grounded in reality, and ensures that every stope can be developed as planned.

Accessibility and Infrastructure Constraints

Stope optimization is meaningless if the shapes cannot be reached with acceptable gradients, turning radii, or ventilation pathways. To avoid this, an access graph is added to the geometric model. It includes levels, blind drifts, raises, and ventilation crosscuts. With this structure, the system applies reachability constraints so that IP/MIP solvers only consider stopes that can be accessed from existing or planned infrastructure.

Reachability and Development Cost Modeling

In simple setups, reachability is defined through a binary matrix that links access nodes to stope centers. In more advanced implementations, it evolves into a development cost function that integrates directly into economic evaluation and scheduling. This ensures stopes are not only geometrically feasible but also economically justified.

Preparing Input for Economic and Optimization Models

Only after clustering stopes along the orebody, trimming geometries, applying MCDM ranking, and validating reachability does it make sense to move into economic calculations or linear and integer optimization. At this stage, the workflow deals with real stopes that can be blasted, ventilated, supported, and backfilled, not abstract polygons from a block model.

Why Geometry Must Come First

Geometry defines the true search space for underground optimization. It filters out mathematically elegant but operationally impossible solutions, ensuring that every subsequent stage is aligned with real-world mining constraints.