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United States Department of Agriculture

Agricultural Research Service

Title: Rock Chutes for Grade Control

Authors
item Robinson, Kerry
item Rice, Charles
item Kadavy, Kem

Submitted to: Management of Landscapes Disturbed by Channel Incision Stabilization Rehabi
Publication Type: Proceedings
Publication Acceptance Date: May 23, 1997
Publication Date: N/A

Interpretive Summary: Rock chutes or riprap-lined channels are used to safely conduct water to a lower elevation. These chutes can offer economic and aesthetic advantages over alternative structures. Information concerning the design of rock chutes is very limited, so research was conducted to develop reliable design criteria. Data were collected relating the highest stable discharge to the average stone size and channel slope. A design equation developed from these data allows the safe design of rock chutes for many applications. Full-size chutes and large rock sizes were used to verify this design tool. The large-scale verification tests increase our confidence in the test results. This research will be of value to public and private water resources engineers. The applications of this technology are numerous, and the interest in this work has been high.

Technical Abstract: Rock chutes or riprap-lined channels are used to safely conduct water to a lower elevation. Rock chutes are well suited for some sites, and they may provide economic as well as aesthetic advantages over alternative structures. Two-dimensional test channels with widths of 0.76, 1.07, and 1.83 m (2.5, 3.5, and 6.0 ft) were used to collect rock chute performance information. Two full size three-dimensional structures with a 2.74-m (9-ft) bottom width and 2:1 side slopes were also constructed and tested to failure. Eight different rock sizes were tested on up to seven different slopes ranging between 8 and 40%. The predominantly angular, crushed limestone rock ranged in size from a median size 15 to 278 mm. The flow rate was increased incrementally until each rock chute failed, and the highest stable discharge was determined for each test. Several stones were repositioned on or removed from the chute prior to a total failure. The test results indicate that a higher stable discharge can be achieved by flattening the slope or increasing the rock size. An empirical equation was developed relating the highest stable discharge to the stone size and channel slope. Test results and chute failure processes are discussed.

Last Modified: 11/27/2014
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