技术报告-尾矿库设计及评估 (英文)(16)

技术报告-尾矿库设计及评估 (英文)

Design and Evaluation of Tailings Dams

Lining the entire impoundment area is more problematic, both because of the expense and because

irregularities in valley side walls and floors make it difficult to ensure consistent liner integrity. Liners or

layers of low permeability may be necessary, however, to impede flows to and from underlying ground water.

More common than impermeable synthetic or clay liners is the practice of compacting native soil, including

any available local clays, to reduce permeability to an acceptable level; dewatered or dried-in-place slimes

may also be used in some cases. Should a liner or low-permeability layer be necessary, it must be designed to

account for impoundment loadings, differential settlement, toxic or corrosive seepage, and weathering effects.

If impoundments will desaturate after reclamation, for example, clay or slimes can crack and provide a

pathway for ground water to enter the tailings or for contaminated seepage to enter ground water. Similarly,

layers of clay or slimes that are prepared in anticipation of late impoundment expansion can develop cracks if

they are allowed to dry before being covered with tailings.

2.2.2Ring-Dike Impoundments

Where natural topographic depressions are not available, the Ring-Dike configuration may be appropriate

(Figure 6). Instead of one large embankment (as in the valley design), embankments (or dikes) are required

on all sides to contain the tailings. Construction can be similar to valley dams, with tailings, waste rock,

and/or other native materials typically used in later phases of construction. Because of the length of the

dike/dam, more materials are necessary for this configuration, and material for the initial surrounding dikes is

typically excavated from the impoundment area.

Figure 5. Single (a) and Multiple (b) Valley-Bottom Impoundments

(Source: Vick 1990)