Subsidence Control by High Volume Grouting

by Kenneth B. Andromalos, Geo-Con Inc, Pittsburgh, PA, USA,
Christopher R. Ryan, Geo-Con Inc, Pittsburgh, PA, USA,

Document Type: Proceeding Paper


Mine grouting programs generally fall into two general methods: flushing and grout columns. With the flushing method, the entire mine under the area to be protected is filled. Grout columns are used to shorten the free span of a mine roof to the point where arching will prevent any spalling from progressing to the ground surface. Because of its fineness and low cost, flyash is commonly used as a bulk filler in both methods. Cement and sometimes coarse aggregate are utilized with the flyash to form the mine grout mixture. Based on conditions encountered at the mine, the consistency and proportions of flyash-cement grout can be modified to suit the mine conditions. The compressive strengths of various flyash-cement grouts used for mine grouting are presented in this paper. The use of high volume grouting techniques utilizing flyash-cement grout slurries for mine subsidence control are discussed. A recent project is discussed to illustrate the techniques, equipment and the grout mix that can be utilized.

Subject Headings: Grouting | Fly ash | Land subsidence | Coal mining | Flushing | Recycling | Mines and mining | Cement

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