堆积体对河道横断面流速分布影响的试验研究
|
摘要
大型泥石流、滑坡等灾害引起的河道堆积体体型较大,会引起河道横断面流速分布的较大改变。为了研究堆积体对河道横断面流速分布的影响,拟通过10组缓坡和6组陡坡河道水槽试验,得出不同尺度堆积体在陡缓坡河道上引起的横断面流速不均匀性的沿程变化结果,并对动能修正系数α和流速横向分布的结果进行分析。结果表明:α的大小能够反映流速断面分布的均匀性,且堆积体的阻水率越大,流速分布的不均匀程度越高;对于缓坡河道,在堆积体河段的x/l=0.5处,流速分布的不均匀程度最大,下游需要较远的距离来消弥堆积体对流速横向分布的影响;对于陡坡河道,流速分布均匀程度的变化主要集中在堆积体河段,且α峰值明显低于缓坡,对上下游影响不大。
Deposits induced by huge landslide or debris flow are of big size,hence changing the cross-sectional velocity distribution of channel to a large extent. The aim of this research is to analyze the influence of deposit on the velocity distribution of channel. According to 16 groups of flume experiments( 10 on flume bed with gentle slope and 6 on steep slope),the uneven cross-sectional velocity distributions along flow direction caused by different deposit size under gentle slope and steep slope conditions are obtained,and the correction factor of kinetic energy αand the cross-sectional velocity distribution are analyzed. Results show that α well represents the velocity uniformity of cross section. As blockage ratio of deposit increases,velocity distribution becomes more uneven. In particular,as for the channel with gentle slope,velocity distribution reaches the most uneven state at the postion when x/l =0. 5; therefore more distance from the upstream of the channel is needed to eliminate deposit's influence on velocity distribution; whereas for the channel with steep slope,the position with uneven change of velocity distribution is mainly located at the deposit reach,and the peak correction factor of kinetic energy is obviously lower than that of the channel with gentle slope,which has less impact on the upstream and downstream.
Deposits induced by huge landslide or debris flow are of big size,hence changing the cross-sectional velocity distribution of channel to a large extent. The aim of this research is to analyze the influence of deposit on the velocity distribution of channel. According to 16 groups of flume experiments( 10 on flume bed with gentle slope and 6 on steep slope),the uneven cross-sectional velocity distributions along flow direction caused by different deposit size under gentle slope and steep slope conditions are obtained,and the correction factor of kinetic energy αand the cross-sectional velocity distribution are analyzed. Results show that α well represents the velocity uniformity of cross section. As blockage ratio of deposit increases,velocity distribution becomes more uneven. In particular,as for the channel with gentle slope,velocity distribution reaches the most uneven state at the postion when x/l =0. 5; therefore more distance from the upstream of the channel is needed to eliminate deposit's influence on velocity distribution; whereas for the channel with steep slope,the position with uneven change of velocity distribution is mainly located at the deposit reach,and the peak correction factor of kinetic energy is obviously lower than that of the channel with gentle slope,which has less impact on the upstream and downstream.
引文
[1]唐川.汶川地震区暴雨滑坡泥石流活动趋势预测[J].山地学报,2010,28(3):341-349.
[2]许强.四川省8·13特大泥石流灾害特点、成因与启示[J].工程地质学报,2010,18(5):596-608.
[3]胥勤勉,杨达源,葛兆帅,等,金沙江金坪子堆积体成因的初步研究[J].山地学报,2006,24(4):403-409.
[4]向先超,涂鹏飞.三峡库区某沟内人工弃土堆积体稳定性研究[J].中国水土保持,2009,(11):35-36.
[5]郭志学,苏杨中,彭清娥,等.堆积体对不同比降河流壅水影响研究[J].四川大学学报(工程科学版),2012,44(5):13-18.
[6]郭志学,彭清娥,汤雷,等.堆积体作用下陡坡河道流速沿程及横向分布规律[J].水利水运工程学报,2011,(4):27-31.
[7]刘家富,彭清娥,郭志学,等.堆积体对河道流速分布的影响研究[J].水利水电技术,2011,42(11):38-41.
[8]何岸霞,周珏西,张婧,等.堆积体对上游附近河道三维流速分布影响的试验研究[J].长江科学院院报,2017,34(8):64-67,71.
[9]周宜林.淹没丁坝附近三维水流运动大涡数值模拟[J].长江科学院院报,2001,18(5):28-31,36.
[10]SARKAR A,RATHA D.Flow around Submerged Structures Subjected to Shallow Submergence over Plane Bed[J].Journal of Fluids and Structures,2014,44(2):166-181.
[11]KUHNLE R,ALONSO C.Flow Near a Model Spur Dike with a Fixed Scoured Bed[J].International Journal of Sediment Research,2013,28(3):349-357.
[12]陈春光,姚令侃,刘翠容,等.泥石流堵河条件的研究[J].水利学报,2013,44(6):648-656.
[13]高桂景.丁坝水力特性及冲刷机理研究[D].重庆:重庆交通大学,2006.
[14]AZINFAR H,KELLS J A.Flow Resistance Due to a Single Spur Dike in an Open Channel[J].Journal of Hydraulic Research,2009,47(6):755-763.
[15]李大美,杨小亭.水力学[M].武汉:武汉大学出版社,2006.
[2]许强.四川省8·13特大泥石流灾害特点、成因与启示[J].工程地质学报,2010,18(5):596-608.
[3]胥勤勉,杨达源,葛兆帅,等,金沙江金坪子堆积体成因的初步研究[J].山地学报,2006,24(4):403-409.
[4]向先超,涂鹏飞.三峡库区某沟内人工弃土堆积体稳定性研究[J].中国水土保持,2009,(11):35-36.
[5]郭志学,苏杨中,彭清娥,等.堆积体对不同比降河流壅水影响研究[J].四川大学学报(工程科学版),2012,44(5):13-18.
[6]郭志学,彭清娥,汤雷,等.堆积体作用下陡坡河道流速沿程及横向分布规律[J].水利水运工程学报,2011,(4):27-31.
[7]刘家富,彭清娥,郭志学,等.堆积体对河道流速分布的影响研究[J].水利水电技术,2011,42(11):38-41.
[8]何岸霞,周珏西,张婧,等.堆积体对上游附近河道三维流速分布影响的试验研究[J].长江科学院院报,2017,34(8):64-67,71.
[9]周宜林.淹没丁坝附近三维水流运动大涡数值模拟[J].长江科学院院报,2001,18(5):28-31,36.
[10]SARKAR A,RATHA D.Flow around Submerged Structures Subjected to Shallow Submergence over Plane Bed[J].Journal of Fluids and Structures,2014,44(2):166-181.
[11]KUHNLE R,ALONSO C.Flow Near a Model Spur Dike with a Fixed Scoured Bed[J].International Journal of Sediment Research,2013,28(3):349-357.
[12]陈春光,姚令侃,刘翠容,等.泥石流堵河条件的研究[J].水利学报,2013,44(6):648-656.
[13]高桂景.丁坝水力特性及冲刷机理研究[D].重庆:重庆交通大学,2006.
[14]AZINFAR H,KELLS J A.Flow Resistance Due to a Single Spur Dike in an Open Channel[J].Journal of Hydraulic Research,2009,47(6):755-763.
[15]李大美,杨小亭.水力学[M].武汉:武汉大学出版社,2006.