BHP San Juan Mine

New Mexico

At the largest underground coal mine in Northern New Mexico equipment near one of the blower fans in the ventilation system was experiencing significant vibrations caused by poor compaction under the fan pad.

Site profiles were generated using shear-wave monitoring (displayed in the image) to determine the nature of the weak soils and help guide the soil stabilization plan. Engineers continued to perform monitoring of the site during grouting to verify densification.

Straight Line grouted four primary locations through the pad eight secondary locations surrounding it. When completed, the fan pad was isolated and surrounding equipment was no longer affected.

Live shear wave velocity monitoring during compaction grouting is an additional tool used to achieve desired results. In this situation, reduction of vibrations affecting surrounding structures was most easily assessed using this tool.