مدل‌ سازی عددی دوبعدی اثر زاویه دیواره سد با تکیه‌ گاه بر ویژگی های سیلاب ناشی از شکست جزئی سد

در تحلیل جریان شکست سد عموماً فرض شده است که دیواره شکست عمود بر تکیه گاه می باشد، از طرفی بخاطر شرایط پایداری به ویژه در سدهای بتنی قوسی دیواره های سد معمولاً بر تکیه گاه عمود نیستند. این انحراف از حالت نرمال به دلیل تغییر حجم مخزن و الگوی جریان در داخل سد می تواند بر هیدرولیک جریان ناشی از شکست سد تاثیر گذار باشد که در این تحقیق مورد بررسی قرار گرفته است. بدین منظور معادلات حاکم بر آب های کم عمق در مختصات منحنی الخط به روش عددی تفاضل محدود صریح منفصل شدند. به منظور پایداری بیشتر به صورت همزمان از الگوریتم های پرش قورباغه و لکس بر روی شبکه جابه جا شده استفاده گردید. با استفاده از داده های اندازه گیری و تحلیلی سایر محققین، توانایی مدل در شبیه سازی شکست ایده آل در حالت های مختلف بررسی شد و نشان داده شد که مدل در تمام موارد با ارائه نتایج قابل قبول، مشخصات جریان را شبیه سازی می نماید. پس از اعتبار سنجی مدل تاثیر زاویه دیواره سد با تکیه گاه مورد بررسی قرار گرفته است. نتایج مدل نشان داد با افزایش انحراف دیواره شکست از حالت نرمال مقدار دبی اوج و اشل حداکثر، کاهش یافته است به گونه ای که به ازای انحراف 2.5، 5، 7.5 و 10 درصد مقدار دبی اوج به ترتیب 3.5، 6.1، 9.2 و 11 درصد و نیز اشل حداکثر به ترتیب 2، 6، 9 و 12 درصد کاهش یافته است.  

two-dimensional numerical modeling of the effect of the angle of the dam with support to the parameters of the flood due to partial dam break

introduction prediction of dam break flood flow characteristic such as water depth and velocities component has always been interesting of hydraulic engineers because of its impact on the severity of the terrible dam break. there are various factors such as hydraulic, hydrological, geotechnical and geometric that affect the characteristics of the dam break flood flow. in order to investigate the effect of the factors, research has been carried out especially experimental, but few numerical research has been done. resource surveys show that although the walls of concrete reservoir dams are not perpendicular to the lateral support, but so far, the effect of wall diversion on the hydraulic properties of the dam break flood flow has not been considered. therefore, in this research, the effect four of 2.5 to 10 percent of the wall diversion of the dam was examined from the normal base. since the wall diversion of the dam from the normal state removes physical space from a rectangular state, the use of cartesian coordinate system is not possible. therefore, in this study, using the curvilinear coordinate system of the physical non- rectangular space studied, it is very accurately converted to computational space and the governing equations are solved.materials and methods the governing equations in the present research are the shallow water equations. due to the inability of the cartesian coordinate system to reflect the physical irregular boundaries of domain, the governing equations were discretized on the curvilinear coordinate system. the explicit method and simultaneously utilize of leap-frog and lax algorithms was used to discretization of the governing equations. results and discussion in order to validate the present model, the model results were compared to experimental data. 1- failure of the dam in the convergent-divergent channel without sloping and sloping: the water surface profile of the experimental model is presented for different times (zero, 4, 20, 60) seconds. the mean error in the results of the present numerical model is 4.02% for the results of the measurements for the non-slope channel and for the channel with a 0.01 slope, 1.65%. 2- simulation of the dam break of a trapezoidal reservoir: the calculated flow and stage hydrographs at dam location were closed to the experimental measured data with reasonable accuracy. 3- the partial symmetric dam break in dry bed is another case investigated in this study, simulation of stage and discharge hydrographs in symmetric dam break in a reservoir with a length and width of one meter for four different diversion of 2.5, 5, 7.5 and 10 percent from normal state was performed in this case .it was observed in the dam break site, depth and flow discharge decreased more. a closer examination shows that for diversion of 2.5, 5, 7.5 and 10 percent, peak discharge values were decreased 3.5, 6.1, 9.2, 11 percent, and the maximum water level was 2, 6, 9 and 12 percent.