Cavity Grouting is most commonly, though not exclusively, used in backfilling abandoned mine workings to avoid the development of settlement or worse, sink holes, at the ground surface above, attributable to the collapse of large underground voids and subsequent progressive upward collapsing above the original void. The process involves drilling into the cavity then pumping grout to either fill the void in part or in full as the design demands.
Cavity Grouting of macro voids with bulk materials has become commonplace, where new construction at the ground surface is proposed above former mine workings.
Design of the cavity grouting has progressed from a requirement for 100% filling of the void, to a reasoned approach, where partial filling of the void is considered sufficient to eliminate the effects of any roof collapse into the workings being evidenced at the surface.
The basic method of cavity grouting for mine workings expressed simply involves drilling a pattern of bores into the workings and pumping a relatively low cement content bulk fill grout into the cavity. This type of work fits very well into the range of activities offered by Menard Bachy, with its range of in-house drilling rigs and its experience in designing purpose specific backfill materials to accommodate different design requirements and achieve economic solutions.
Issues for consideration in Cavity Grouting:
These issues determine the design approach to be adopted as the best solution.