REP02129 - Laserfiche WebLink

Home Browse Search

16 ' section in soils is shortened; this solution would increase the height of the portal cut. Potential stability problems related it to a high portal cut might be severe if the cut.is close to the steep slope above the bench. ! 1 I, The tunnels can significantly contribute to dewatering the ' ~I -area behind the portal. However, if they were fully lined with !~ an impermeable liner, they would not function as drains. We recommend that provisions for drainage into individual tunnels are made so that effective drainage of the area can be enhanced. It can be expected that the tunnels will practically replace ' ~ the drainage systems which would be installed earlier. ' 3.3 ACCESS ROAD I ' The proposed access road below the mine bench will be con- structed partly within the landslide area. The design and con- ' struction of the section within the landslide have been di- 'i cussed on numerous occasions with the representatives of Merrick and Company. We have recommended that the necessary earth work ' !. be kept to a minimum so that high cuts or fills are avoided. This ' is difficult within the road section immediately below the pro- ' ~ posed bench where the road alignment traverses a steep natural slope. i ~'; Because of the steep slope gradient, cuts or fills cannot ' , be constructed without appropriate retaining structures; it can !~ be expected that soil thickness on the order of 20 feet or more I will be encountered, and soil cuts are not feasible. 1 ' A typical cross-section of the road within this section ' ~ will include a cut supported by a retaining wall and a fill supported by another retaining wall. In order to evaluate the 1 ~ stability of such a cross-section, we have performed several stability analyses assuming the same soil properties as those ~«.,.o~.,~ ..~ 1