Use of geocells for lining a steep drainage channel in mining area: Fid-Bau Portal

Use of geocells for lining a steep drainage channel in mining area

Abramento, M. / Wickert, F. / Franca, P. / Franco, D. / Duraes, D. / Senf, D.

In the metropolitan region of Belo Horizonte there are several mining companies which extract iron and other metals in the surrounding area. Mining activities result in waste dumps, which are usually constructed in valleys adjacent to the mining area. The waste material is highly heterogeneous, with components from fine soils to large stones and boulders. Drainage control is achieved through peripheral channels, which are usually made of rock fill or lined with concrete. This paper presents an alternative solution to lining a drainage channel, using geosynthetics product. The channel is trapezoidal with side slopes of 1H:1V, 1.5 m deep and 6 m wide at the base. It has bed slope of 45 degrees of angle and an approximate length of 500 m. The solution consisted in lining the channel with an HDPE geocell filled with concrete. Initially the cells were to be fixed by means of steel anchors inserted along the channel slopes and base. However, during installation there was great difficulty in inserting the anchors in the ground due to large amount of stones in the waste pile. For this reason, the anchoring system was modified and consisted of installing the up-slope end of the geocell sections in trenches excavated across the channel slopes and bottom. Two months after completion of the lining, an estimated 500-year rain occurred in the area, totaling 90 mm in 5 hours. The lining had already been submitted to a previously heavy rain of 227 mm in 14 hours. These events lead to the displacement of large boulders from the waste pile to the channel bed. Some of these stones stopped at an intermediate berm. Even though the lining was submitted to these high stresses, it showed satisfactory performance, with no significant damage.