HYDRO24780 - Laserfiche WebLink

Home Browse Search

Mogul Mine Bulkhead Certification Report Page 3 Construction of concrete forms and erection of rebar caves The forms were constructed of vertical 8"x8" S4S posts and horizontal 2"x12" and 2"x6" S4S lagging. The form interior was lined with'/<" plywood for additional strength. Bracing consisted of angle iron and pipe anchored to the ribs, sill and back of the drift. The form construction and bracing was adequate to prevent movement or failure during filling of the forms. The rebar cages were supported by dowels (rebaz) grouted into the rib. The upstream rebaz cage is #6 bazs on a 12"x12" grid and the downstream rebirr.cage is #8 bazs on a 12"x 12" grid. The minirnum cleaz distance from the form to the rebaz is 3.5". The minimum bullchead length was specified to be 9' and the actual :length was 9'. Trim bazs (5' long) were placed at 45° to the rebar around the cutouts in the rebaz cage for the pipe. All minimum clearances, dimensions and spacings met design criteria and were inspected by the design engineer prior to filling of the forms. Perimeter area irre¢ularity The rock contact perimeter area irregularity required to develop 'the design compressive strength of the concrete when subject to the maximum design thrust was determined to require a projection of 0.14" or more. Quantification of a minimiun perimeter area irregularity was not specifically calculated due to the irregularity on the back, ribs and floor extending more than 1 ft. into the tunnel cross section. Pumnine of concrete, filline of forms and concrete compressive strength The following concrete mix was used for this bulkhead. The concrete mix was as follows: #/cu. vd. Portland Type R 720 Sand 1692 Fine Aggregate - 3/8" 1093 Fly Ash, Class F 115 Water 324 Delay Set The concrete was batched from the portable 5andco batch plant that was set up in Silverton. This is the same plant and concrete supplier used for the American Tunnel