Avantages et inconvénients des jumbos de forage pour le développement des galeries souterraines
Drill jumbos have become an increasingly common choice for heading development, but they also have clear limitations in underground mining. One practical summary is: in dddhhhlong, large, hard, and high-gradedddhhh conditions a drill jumbo can multiply efficiency; under other conditions it may simply inflate costs.
Advantages when conditions are suitable
Drilling speed: a three-boom drill jumbo can achieve single-cycle advance rates 3–6 times faster than a jackleg pneumatic drill; monthly advance can be stably maintained at around 130 m in favorable conditions.
Hole quality: jumbos produce very small hole-position deviations (typically below ~2 cm in many reports), reduce overbreak by roughly 10%, and form more uniform blast faces. This lowers shotcrete support needs and downstream processing/transport costs.
Improved safety: operators work from cabins, reducing the number of personnel at the face to about two. Dust and noise are greatly reduced, improving both face safety and personnel protection.
Economic efficiency for long headings: after depreciation, savings on labor, power, consumables, detonators and explosives can reach roughly 15% on long runs.
Disadvantages when conditions are unfavorable
High capital cost: upfront investment is large. Two‑boom jumbos are commonly priced in the range of RMB 3–6 million per unit, with spare-part inventory typically about 5% of asset value—making them expensive compared with jackleg drills.
Cross-section requirements: most general-purpose jumbos require a net heading width ssshhh4.0 m and height ssshhh3.8 m. Smaller sections, particularly below about 2.0 m, are not suitable for standard jumbos and need specialized small rigs, reducing universality.
Geology sensitivity: jumbos perform well in competent hard rock, but in soft ground, fractured zones, or water-bearing bands they are prone to frequent bit jamming and other interruptions; in such conditions their effective productivity can be lower than that of jackleg drills.
Maintenance demands: jumbos are integrated hydraulic–electrical systems (hydraulics, controls, lubrication) that require skilled maintenance personnel. Failures of core components (pumps, valves) often cost an entire shift to repair during early adoption, which can discourage operators.
Slow relocation: jumbos are heavy and often transported in sections for shaft descent and reassembly; moving between working faces or during multi-segment advance can be time-consuming in confined underground spaces.
Typical applicable conditions and operational recommendations Jumbos are most appropriate where the heading cross-section exceeds ~16 m², single-heading advance lengths exceed ~300 m, rock hardness is moderate or greater (described here as “hardness ssshhh6”), and capital plus a professional maintenance team are available. When those conditions are not met, mixed-mode or alternative approaches are advised:
Use a hybrid “jumbo + jackleg” workflow or continue with pure jackleg operations to avoid inverted efficiency (where the jumbo is slower or more costly).
Deployment suggestions by scenario:
Large transport headings or long tunnels: three‑boom hydraulic jumbos.
Mid-size mines with intermediate headings: single‑ or double‑boom lightweight modular jumbos (heading length should still be ssshhh300 m to justify).
Small headings (about 2.5 × 2.5 m and below): jackleg pneumatic drills are preferable; jumbos cannot realize advantages in these sections.
Highly fractured or alternating soft‑rock headings: use a jumbo for primary holes and jackleg drills to supplement problematic holes, switching in real time according to face conditions to reduce jamming.
Outlook Overall, drill jumbos remain a development trend. Prices are expected to decline gradually while designs become more compact, electrified, modular, and suitable for series production. With digitalization and intelligent systems advancing, 5G remote control and AI‑driven adaptive drilling-parameter optimization are feasible future directions that will further expand jumbo applicability.
