بررسي مشخصه هاي هيدروليكي جريان در سرريزهاي گابيوني مورب با مقطع ذوزنقه اي

چكيده انگليسي :

Hydraulic characteristics of flow over oblique trapezoidal gabion weirs Marzieh Samani samani marzieh@yahoo com Date of submission July 2 2019 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree MSc Language Farsi Supervisor Dr Abdorreza Kabiri Samani akabiri@cc iut ac ir Dr Mohammad Reza Chamani mchamani@cc iut ac ir AbstractWeirs are used to control flood flow to regulate water level and to measure flow discharge inhydraulic systems These hydraulic structures are typically made of concrete having animpermeable build thereby flow just passes over their crown By placing an impermeable weiracross a river the aquatic ecosystem is affected and suspended materials movement toward thedownstream is prevented Therefore these weirs have many negative effects on the downstreamenvironment In contrast gabion weirs with some merits including sustainability permeabilityand cost effectiveness are of the suitable hydraulic structures to meet the stated objectives Theseweirs are structurally stable and resistant to loads caused by great values of approach flowdischarges having favorable efficiency of flow energy dissipation These weirs can be installedand operate in various forms in the rivers and canals To increase the length of the weir crest they can be used obliquely in respect to the approach flow direction Due to the increase of theeffective weir crest length the overflow discharge over the oblique weirs increases and thehydraulic aspects of flow such as the discharge coefficient are improved On the basis of the improved features and benefits of gabion weirs as well as the increasedperformance of oblique weirs compared to the frontal normal weirs the present studyinvestigates the hydraulic characteristics of flow over oblique gabion weirs with differentgeometries The purpose of this study was to investigate the effect of different geometrical andhydraulic parameters on the discharge coefficient threshold submergence depth and energy loss For this purpose 12 Gabion weir models were installed in a flume of 11 m long 0 4 m wide and0 7 m deep in the hydraulic laboratory department of civil engineering Isfahan University ofTechnology Isfahan Iran This investigation covers different materials with average diameter of11 16 and 21 mm with porosity of 0 33 0 35 and 0 39 and oblique gabion weirs with differentdownstream angles of 0 30 45 and 60 degrees in respect to a vertical direction The oblique weirsangles were 0 30 45 and 60 degrees in respect to the approach flow direction with the crestwidths of 50 100 and 150 mm and the heights of 100 and 200 mm The effects of eachdimensionless parameter on flow discharge coefficient energy loss and threshold submergencedepth was investigated Results show that by increasing the angle of obliqueness the flow discharge coefficient decreasesand the energy loss and threshold submergence depth increase However by increasing thisangle the flow discharge increases For the gabion weirs as the aggregates size and the porosityincrease the overflow discharge coefficient increases and the threshold submergence depth andthe flow head loss decrease Generally the discharge coefficient and the flow energy loss ofgabion weirs are both greater than those of impermeable weirs The influences of other

ساماني، مرضيه

بررسي مشخصه هاي هيدروليكي جريان در سرريزهاي گابيوني مورب با مقطع ذوزنقه اي

ضريب دبي , جريان آزاد , آستانه استغراق , افت انرژي , سرريز گابيوني , سرريز زاويه دار