ojuego
Civil/Environmental
- Jan 25, 2014
- 17
Hi,
I have a follow-up question about a flume I am designing to carry stormwater outside. It is to be of reinforced concrete in a U-shape, with #3 bars in a single mat through the U-shape, with the bars both horizontally and vertically. The depth is to be only about 1.42 ft (1 ft 5 inches) including the floor depth. The walls and floor are to be fairly thin (due to site constraints), at 0.42 ft (5 inches). The flume is to be dug into previously placed fill material outside a house with a fairly deep foundation. Should there be something like 4" depth of gravel underneath the concrete? The job site is not in an area subject to freeze-thaw conditions (a far southern state). If needed, what size of gravel is recommended? What is the purpose of such gravel? And, lastly, in the area of the project, "flexible base" is often used for roadway base material. Could such be used under the flume? Gradation requirements for flexible base are as follow: 1-3/4" 0% retained; 7/8" 10%-35% retained; 3/8" 35%-50% retained; #4 sieve 45%-65% retained; #40 sieve 70% - 85% retained. Or, would it be recommended to just forget about the potential use of flexible base, and just call out for 3/4" gravel under the flume (if it is needed at all).
Thanks!
I have a follow-up question about a flume I am designing to carry stormwater outside. It is to be of reinforced concrete in a U-shape, with #3 bars in a single mat through the U-shape, with the bars both horizontally and vertically. The depth is to be only about 1.42 ft (1 ft 5 inches) including the floor depth. The walls and floor are to be fairly thin (due to site constraints), at 0.42 ft (5 inches). The flume is to be dug into previously placed fill material outside a house with a fairly deep foundation. Should there be something like 4" depth of gravel underneath the concrete? The job site is not in an area subject to freeze-thaw conditions (a far southern state). If needed, what size of gravel is recommended? What is the purpose of such gravel? And, lastly, in the area of the project, "flexible base" is often used for roadway base material. Could such be used under the flume? Gradation requirements for flexible base are as follow: 1-3/4" 0% retained; 7/8" 10%-35% retained; 3/8" 35%-50% retained; #4 sieve 45%-65% retained; #40 sieve 70% - 85% retained. Or, would it be recommended to just forget about the potential use of flexible base, and just call out for 3/4" gravel under the flume (if it is needed at all).
Thanks!
