تأثیر استفاده از طوق بیضوی در کاهش آب‌شستگی اطراف پایه پل

نویسندگان

چکیده

به‌دلیل اهمیت زیاد آب‌شستگی،‏ پژوهش‌گران زیادی به بررسی این پدیده پرداخته و روش‌های مختلفی برای کنترل آن ارائه کردند. این روش‌ها را می‌توان به دو گروه کلی،‏ افزایش مقاومت بستر و تغییر الگوی جریان تقسیم کرد. طوق‌ها صفحاتی هستند که موازی با بستر و عمود بر پایه نصب شده و در بالادست پایه،‏ مانعی در مقابل جریان روبه پایین بوده و از تشکیل حفره آب‌شستگی جلوگیری می‌کنند. در این پژوهش اثر طوق بیضوی بر میزان کاهش آب‌شستگی بررسی شده است بدین منظور از 3 طوق بیضوی با نسبت طول طوق در پایین‌دست پایه به قطر پایه ( ) برابر با 1،‏ 5‎/1 و 2 و ضخامت 3 میلی‌متر استفاده شد. طول،‏ عرض و عمق کانال آزمایشگاهی به‌ترتیب برابر با 8،‏ 255‎/0 و 3‎/0 متر و اندازه متوسط ذرات بستر 88‎/0 میلی‌متر بوده است. از پایه استوانه‌ای به قطر 21 میلی‌متر و 5 دبی مختلف استفاده شد. نتایج نشان داد که حجم گودال آب‌شستگی در حالت استفاده از طوق در مقایسه با آزمایش‌های پایه بدون طوق کاهش یافته است. بیشترین مقدار کاهش حجم مربوط به طوق بیضوی با نسبت بدون بعد طول طوق پایین‌دست پایه به قطر پایه برابر با 5‎/1 بوده که این مقدار کاهش در عدد فرود جریان 246‎/0 برابر 5‎/81 درصد بوده است. کمترین مقدار کاهش هم مربوط به طوقی به ابعاد در عدد فرود جریان 294‎/0 بوده که مقدار آن برابر با 36‎/13 درصد است.

کلیدواژه‌ها


عنوان مقاله [English]

The effect of using elliptical collar in reduction of scour around bridge pier

نویسندگان [English]

  • seyed javad meshkavati toroujeni
  • mohsen masoudian
  • seyed mojtaba sanei
  • mir khalegh zia tabar ahmadi
چکیده [English]

Due to importance of scouring, numerous researchers have investigated the local scouring and various methods suggested for controlling this phenomenon. These methods can be divided into two general categories, increasing the bed resistance and changing the flow pattern. The collars are plates which installed parallel to the bed on the pier; operate as an obstacle against the down flow and prevent the formation of the scour hole at the upstream side of the pier. The current research investigated the effect of elliptical collar on scouring process. For this purpose, three elliptical collars with the ratio of the collar length at the downstream of the pier to the pier diameter ( ) of 1, 1.5, 2, the 3 mm thickness and cylindrical pier with 21 mm diameter, were examined at 5 different discharges. Also, the Length, width and depth of the laboratory flume were 8, 0.255 and 0.3 meters, respectively, and the mean size of the bed sediment was 0.88 mm. The results showed that utilizing the collar led to reduce the scour volume in comparison with the usage of the pier without collar. The maximum (81.5%) and minimum (13.36%) scour reduction were belonged to the elliptical collars with and , at Froude numbers of 0.246 and 0.294, respectively.

Due to importance of scouring, numerous researchers have investigated the local scouring and various methods suggested for controlling this phenomenon. These methods can be divided into two general categories, increasing the bed resistance and changing the flow pattern. The collars are plates which installed parallel to the bed on the pier; operate as an obstacle against the down flow and prevent the formation of the scour hole at the upstream side of the pier. The current research investigated the effect of elliptical collar on scouring process. For this purpose, three elliptical collars with the ratio of the collar length at the downstream of the pier to the pier diameter ( ) of 1, 1.5, 2, the 3 mm thickness and cylindrical pier with 21 mm diameter, were examined at 5 different discharges. Also, the Length, width and depth of the laboratory flume were 8, 0.255 and 0.3 meters, respectively, and the mean size of the bed sediment was 0.88 mm. The results showed that utilizing the collar led to reduce the scour volume in comparison with the usage of the pier without collar. The maximum (81.5%) and minimum (13.36%) scour reduction were belonged to the elliptical collars with and , at Froude numbers of 0.246 and 0.294, respectively.

Due to importance of scouring, numerous researchers have investigated the local scouring and various methods suggested for controlling this phenomenon. These methods can be divided into two general categories, increasing the bed resistance and changing the flow pattern. The collars are plates which installed parallel to the bed on the pier; operate as an obstacle against the down flow and prevent the formation of the scour hole at the upstream side of the pier. The current research investigated the effect of elliptical collar on scouring process. For this purpose, three elliptical collars with the ratio of the collar length at the downstream of the pier to the pier diameter ( ) of 1, 1.5, 2, the 3 mm thickness and cylindrical pier with 21 mm diameter, were examined at 5 different discharges. Also, the Length, width and depth of the laboratory flume were 8, 0.255 and 0.3 meters, respectively, and the mean size of the bed sediment was 0.88 mm. The results showed that utilizing the collar led to reduce the scour volume in comparison with the usage of the pier without collar. The maximum (81.5%) and minimum (13.36%) scour reduction were belonged to the elliptical collars with and , at Froude numbers of 0.246 and 0.294, respectively.

Due to importance of scouring, numerous researchers have investigated the local scouring and various methods suggested for controlling this phenomenon. These methods can be divided into two general categories, increasing the bed resistance and changing the flow pattern. The collars are plates which installed parallel to the bed on the pier; operate as an obstacle against the down flow and prevent the formation of the scour hole at the upstream side of the pier. The current research investigated the effect of elliptical collar on scouring process. For this purpose, three elliptical collars with the ratio of the collar length at the downstream of the pier to the pier diameter ( ) of 1, 1.5, 2, the 3 mm thickness and cylindrical pier with 21 mm diameter, were examined at 5 different discharges. Also, the Length, width and depth of the laboratory flume were 8, 0.255 and 0.3 meters, respectively, and the mean size of the bed sediment was 0.88 mm. The results showed that utilizing the collar led to reduce the scour volume in comparison with the usage of the pier without collar. The maximum (81.5%) and minimum (13.36%) scour reduction were belonged to the elliptical collars with and , at Froude numbers of 0.246 and 0.294, respectively.

کلیدواژه‌ها [English]

  • Hydraulic of Bridge-Bridge Pier-Scouring.-Collar-