American Society of Civil Engineers


Hydraulic Characteristics of Gabion-Stepped Weirs


by Chaiyuth Chinnarasri, (corresponding author), (Assoc. Prof., Water Resour. Engrg. Res. Lab. (WAREE), Dept. of Civ. Engrg., King Mongkut’s Univ. of Technol. Thonburi, Bangkok 10140, Thailand E-mail: chaiyuth.shi@kmutt.ac.th), Somchai Donjadee, (Lect., Dept. of Irrigation Engrg., Kasetsart Univ., Kampaeng Saen Campus, Nakorn Pathom 71340, Thailand. E-mail: t_donjadee@yahoo.com), and Udomsak Israngkura, (Asst. Prof., Dept. of Civ. Engrg., King Mongkut’s Univ. of Technol. Thonburi, Bangkok 10140, Thailand. E-mail: udomsak.isr@kmutt.ac.th)

Journal of Hydraulic Engineering, Vol. 134, No. 8, August 2008, pp. 1147-1152, (doi:  http://dx.doi.org/10.1061/(ASCE)0733-9429(2008)134:8(1147))

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Document type: Technical Note
Closure:(See full record)
Discussion: by Anant I. Dhatrak E-mail: anantdhatrak@rediffmail.com and et al.    (See full record)
Abstract: Experimental studies on the hydraulics of flow through and over gabion-stepped weirs are presented. Two flow components were observed, i.e., base flow through the void between filled stones and overflow on the gabions. The energy loss ratios in the gabion-stepped weirs are greater than those in the corresponding horizontal stepped weirs by approximately 7, 10, and 14% for weir slopes of 30, 45, and 60°, respectively. As a result, the velocity at the outlet is lower. Stone size and shape have little influence on the energy loss and flow velocity as compared to the increasing effect of the weir slope. The pressure acting on the step face for the gabion-stepped weirs is less than that of the horizontal steps owing to the cushioning effect generated by filled stones. To reduce pressure on a step face at a fixed discharge for different weir slopes, the void ratio of the filled stones should be low to allow a small amount of base flow. The pressure distribution pattern on the horizontal face of a step is provided.


ASCE Subject Headings:
Weirs
Hydraulic structures
Overflow
Energy
Pressure measurement