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Lined waterway or outlet Lined waterway or outlet

Lined waterway or outlet - PowerPoint Presentation

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Uploaded On 2016-03-02

Lined waterway or outlet - PPT Presentation

Chute Design Standard 468 Criteria Stable rock sizes and flow depths for rocklined channels having gradients between 2 percent and 40 percent may be determined using the following detailed design process This design process is from ID: 238903

design rock slopes robinson rock design robinson slopes standard chutes factor kadavy rice safety chute 468 originally paper lined

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Slide1

Lined waterway or outlet

Chute DesignSlide2

Standard 468 - Criteria

Stable rock sizes and flow depths for rock-lined channels having gradients between 2 percent and 40 percent may be determined using the following detailed design process. This design process is from

Design of Rock Chutes by Robinson, Rice,

and Kadavy.For channel slopes between 2% and 10%:D50 = [q (S)1.5/4.75(10)-3]1/1.89For channel slopes between 10% and 40%:D50 = [q (S)0.58/3.93(10)-2]1/1.89z = [n(q )/1.486(S)0.50]3/5Slide3

Design of Rock Chutes

Robinson, Rice, & Kadavy, 1998

Full scale testing of rock chutes.

38 chutes, slopes 2% - 40%9’ bottom, 2:1 side slopesRecommendations of paper based upon:Angular RiprapRiprap Coefficient of Uniformity (Cu)1.25 – 1.75Cu = D60/D10Slide4

C

u

C

u = 1.375Robinson …

C

u

= 4.4

MNTR3Slide5

Robinson - Factor of Safety

Not Addressed in Standard 468

Not Addressed in “

Design of Rock Chutes” by Robinson, Rice, and KadavyMinimum of 1.2 recommended by RobinsonSlide6

Standard 468 deficiencies

The Robinson paper is the “State of the Art” for rock chute design, but the reference in the standard is incomplete

C

u of rock should be between 1.25 and 1.75A factor of safety of 1.2 should be applied to the resulting D50Slide7

Recommended Tool

Spreadsheet:

Rock Chute 401.xls

Originally written by Eric LorenzVariable factor of safety and Cu < 2.0Spreadsheet originally written for the design of rock chutes, contains hydraulic design considerations that may not be required for a waterway outletComputes a rock thickness of 2 * D50 which is on the low size. Recommend following MN TR3 and use 1.25*D100 (upper limit) = 2.5*D50