Settlement Behavior of New Primary Crusher Foundation

2016-02-20

A new primary crusher was built next to an existing crusher as part of a copper mine expansion in the Chilean Andes. Because the site is topographically constrained and elevations exceed 3,000m, only limited subsurface investigation was possible.

Geotechnical characterizations of the soil and rock horizons were developed using information from this investigation and a previous investigation performed for the existing crusher. The natural soils are mainly Colluvial sandy/silty gravels overlying bedrock. Some fill was placed during previous construction. Portions of the existing natural soils had to be undercut and structural fill placed beneath the new, roughly 22m x 22m, crusher foundation. Additional areas were filled to establish a level platform for constructing a 25m high mechanically stabilized earth (MSE) wall adjacent to the new crusher. The wall provided a higher platform from which mine trucks could dump large materials for crushing.

The effects of the MSE wall on the behavior of the new crusher foundation were analyzed to estimate settlements and anticipate possible rotational movements. These were particularly sensitive issues because they were excessive for the existing crusher. Topographic records of foundation settlement during MSE wall erection and crusher assembly indicate that performance satisfied the design criteria.