Preventive Consolidation of a Regional Fault During Mechanized Excavation

Crossing a wide, water-bearing regional fault is one of the most demanding challenges in mechanized underground excavation. This case study documents how a preventive ground consolidation program allowed a silver mine to cross such a structure safely and continuously, in ground where earlier developments in the same district had stalled and collapsed.

Working on a 5.0 m by 4.5 m access drift, the team began peripheral, spiling-type resin injections approximately 21 metres ahead of the anticipated fault contact. The drilling template combined 13 crown boreholes and five boreholes per rib at three staggered lengths (8, 12 and 21 m), delivering near-face, intermediate and deep anticipatory reinforcement. Self-drilling anchors installed in every borehole served a dual role: permanent structural reinforcement and a distribution medium for the resin, producing composite ground behaviour.

Consolidation used Marisil^® E, a two-component organo-mineral elastic resin selected for its four-minute reaction time, non-foaming behaviour, strong adhesion and reaction in wet conditions, and roughly 30 MPa compressive strength at 50% deformation. Injection proceeded sequentially, starting with one-third of the holes, and was adapted in real time from pressures, consumption, water behaviour and visible resin returns.

The fault, ultimately confirmed at up to about 5 m thick rather than the predicted 1 to 2 m, was crossed with no major incidents. Advance recovered from as little as 1 m/day in untreated ground to roughly 3 m/day once consolidated, with no measurable overbreak, controlled water inflows and improved safety for personnel and equipment. The results confirm the effectiveness of hybrid chemical consolidation and mechanical reinforcement for managing extreme geotechnical conditions.

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