不同底床坡度下的堰塞坝溃决过程研究
|
摘要
针对缺乏底床坡度对堰塞坝溃决过程影响的现状,采用7种底床坡度(1°,2°,3°,7°,9°,11°,13°)进行堰塞坝溃决试验,结果表明:不同底床坡度条件下的堰塞坝溃决过程分为3个阶段,其中第I阶段溃口发展缓慢,在背水坡形成明显的水流坡折点,第II阶段溯源侵蚀强烈,溃口快速下切和展宽,溃口类似于梯形,第III阶段水沙运动减弱并趋于平衡。峰值流量与底床坡度呈非单调关系,其随底床坡度的增大先增大后减小。当底床坡度较小时,溯源侵蚀是溃口下切的主要动力;随底床坡度逐渐增大,牵引侵蚀对溃口纵向和横向发展的作用增大。溃口宽度与深度之比随底床坡度的增大先增大后减小,且以3°为分界值。溃决后的溃口宽深比随底床坡度的增大呈先趋于1,后渐小于1的规律。
Natural dams formed by landslides may produce disastrous floods after dam outburst. However,the breaching characteristics of natural dams influenced by bed slopes are still unclear. In this paper,a series of laboratory tests including seven different flume bed slope angles(1°,2°,3°,7°,9°,11°,and 13°)are conducted.The results show that three stages are observed during dam breaching. In stageⅠ,the breach develops slowly.And,flow break point is occurred on downstream slope. In stageⅡ,the breach develops quickly in depth and width due to backward erosion. The shape of the breach is similar to trapezoid during this period. In stage Ⅲ,the flow water and sediment turns to a new balance. There is a non-monotonic relationship between peak discharge and channel bed slope. With increasing of channel bed slope,peak discharge increases firstly and then decreases.The backward erosion is the main driving force to deepen the breach when slope angle is small. However,the development of the breach could be seriously influenced by traction erosion when slope angle is large. When channel bed slope is below 3°,the ratio of breach width to depth increases as the channel bed slope increasing.Otherwise,the ratio of breaching width to depth decreases with the same tendency. The ratio of breach width to depth after dam failure tends to be 1 and then less than 1 with the slope increasing.
Natural dams formed by landslides may produce disastrous floods after dam outburst. However,the breaching characteristics of natural dams influenced by bed slopes are still unclear. In this paper,a series of laboratory tests including seven different flume bed slope angles(1°,2°,3°,7°,9°,11°,and 13°)are conducted.The results show that three stages are observed during dam breaching. In stageⅠ,the breach develops slowly.And,flow break point is occurred on downstream slope. In stageⅡ,the breach develops quickly in depth and width due to backward erosion. The shape of the breach is similar to trapezoid during this period. In stage Ⅲ,the flow water and sediment turns to a new balance. There is a non-monotonic relationship between peak discharge and channel bed slope. With increasing of channel bed slope,peak discharge increases firstly and then decreases.The backward erosion is the main driving force to deepen the breach when slope angle is small. However,the development of the breach could be seriously influenced by traction erosion when slope angle is large. When channel bed slope is below 3°,the ratio of breach width to depth increases as the channel bed slope increasing.Otherwise,the ratio of breaching width to depth decreases with the same tendency. The ratio of breach width to depth after dam failure tends to be 1 and then less than 1 with the slope increasing.
引文
[1]TAKAHASHI T,Debris flow:mechanics,prediction and countermeasures[M].London,UK:Taylor and Francis Group press,2007:143.
[2]COSTA J E,SCHUSTER R L.The formation and failure of natural dams[J].Geological Society of America Bulletin,1988,100(7):1 054-1 068.
[3]HANISCH J.Usoi landslide dam in Tajikistan-the world's highest dam:first stability assessment of the rock slopes at Lake Sarez[C]//Proceedings of the 1st European Conference on Landslides.[S.l.]:[s.n.],2002:189-197.
[4]ZECH Y,SOARES-FRAZ?O S,SPINEWINE B,et al.Dam-break induced sediment movement:experimental approaches and numerical modelling[J].Journal of Hydraulic Research,2008,46(2):176-190.
[5]PICKERT G,WEITBRECHT V,BIEBERSTEIN A.Breaching of overtopped river embankments controlled by apparent cohesion[J].Journal of Hydraulic Research,2011,49(2):143-156.
[6]ROZOV A L.Modeling of washout of dams[J].Journal of Hydraulic Research,2003,41(6):565-577.
[7]CAO Z,YUE Z,PENDER G.Landslide dam failure and flood hydraulics.Part I:experimental investigation[J].Natural Hazards,2011,59(2):1 003-1 019.
[8]CAO Z,YUE Z,PENDER G.Landslide dam failure and flood hydraulics.Part II:coupled mathematical modelling[J].Natural Hazards,2011,59(2):1 021-1 045.
[9]DOU S T,WANG D W,YU M H,et al.Numerical modeling of the lateral widening of levee breach by overtopping in a flume with 180°bend[J].Natural Hazards and Earth System Sciences,2014,14(1):11-20.
[10]SINGH V P,QUIROGA C A.A dam-breach erosion model:I.Formulation[J].Water Resources Management,1987,1(3):177-197.
[11]FREAD D L.Breach:an erosion model for earthen dam failures[R].Silver Spring MA:National Weather Service,NOAA,1988.
[12]WALDER J S,O?CONNOR J E.Methods for predicting peak discharge of floods caused by failure of natural and constructed earthen dams[J].Water Resources Research,1997,33(10):2 337-2 348.
[13]MACCHIONE F.Model for predicting floods due to earthen dam breaching.I:Formulation and evaluation[J].Journal of Hydraulic Engineering,2008,134(12):1 688-1 696.
[14]BELIKOV V V,VASIL?EVA E S,PRUDOVSKII A M.Numerical modeling of a breach wave through the dam at the Krasnodar reservoir[J].Power Technology and Engineering:formerly Hydrotechnical Construction,2010,44(4):269-278.
[15]MA H,FU X.Real time prediction approach for floods caused by failure of natural dams due to overtopping[J].Advances in Water Resources,2012,35:10-19.
[16]FAN X,TANG C X,VAN WESTEN C J,et al.Simulating dam-breach flood scenarios of the Tangjiashan landslide dam induced by the Wenchuan Earthquake[J].Natural Hazards and Earth System Sciences,2012,12(10):3 031-3 044.
[17]COLEMAN S E,ANDREWS D P,WEBBY M G.Overtopping Breaching of Noncohesive Homogeneous Embankments[J].Journal of Hydraulic Engineering,2002,128(9):829-838.
[18]MORRIS M W,HASSAN M,VASKINN K A,Breach formation:Field test and laboratory experiments[J].Journal of Hydraulic Research,2007,45(Supp.1):9-17
[19]LIU N,CHEN Z,ZHANG J X,et al.Draining the Tangjiashan barrier lake[J].Journal of Hydraulic Engineering,2010,136(11):914-923.
[20]DO X K,KIM M,NGUYEN H P T,et al.Analysis of landslide dam failure caused by overtopping[J].Procedia Engineering,2016,154:990-994.
[21]ZHU Y H,VISSER P J,VRIJLING J K,et al.Experimental investigation on breaching of embankments[J].Science China Technological Sciences,2011,54(1):148-155.
[22]SCHMOCKER L,HAGER W H.Modelling dike breaching due to overtopping[J].Journal of Hydraulic Research,2009,47(5):585-597.
[23]SCHMOCKER L,FRANK P J,HAGER W H.Overtopping dike-breach:effect of grain size distribution[J].Journal of Hydraulic Research,2014,52(4):559-564.
[24]CHANG D S,ZHANG L M.Simulation of the erosion process of landslide dams due to overtopping considering variations in soil erodibility along depth[J].Natural Hazards and Earth System Sciences,2010,10(4):933-946.
[2]COSTA J E,SCHUSTER R L.The formation and failure of natural dams[J].Geological Society of America Bulletin,1988,100(7):1 054-1 068.
[3]HANISCH J.Usoi landslide dam in Tajikistan-the world's highest dam:first stability assessment of the rock slopes at Lake Sarez[C]//Proceedings of the 1st European Conference on Landslides.[S.l.]:[s.n.],2002:189-197.
[4]ZECH Y,SOARES-FRAZ?O S,SPINEWINE B,et al.Dam-break induced sediment movement:experimental approaches and numerical modelling[J].Journal of Hydraulic Research,2008,46(2):176-190.
[5]PICKERT G,WEITBRECHT V,BIEBERSTEIN A.Breaching of overtopped river embankments controlled by apparent cohesion[J].Journal of Hydraulic Research,2011,49(2):143-156.
[6]ROZOV A L.Modeling of washout of dams[J].Journal of Hydraulic Research,2003,41(6):565-577.
[7]CAO Z,YUE Z,PENDER G.Landslide dam failure and flood hydraulics.Part I:experimental investigation[J].Natural Hazards,2011,59(2):1 003-1 019.
[8]CAO Z,YUE Z,PENDER G.Landslide dam failure and flood hydraulics.Part II:coupled mathematical modelling[J].Natural Hazards,2011,59(2):1 021-1 045.
[9]DOU S T,WANG D W,YU M H,et al.Numerical modeling of the lateral widening of levee breach by overtopping in a flume with 180°bend[J].Natural Hazards and Earth System Sciences,2014,14(1):11-20.
[10]SINGH V P,QUIROGA C A.A dam-breach erosion model:I.Formulation[J].Water Resources Management,1987,1(3):177-197.
[11]FREAD D L.Breach:an erosion model for earthen dam failures[R].Silver Spring MA:National Weather Service,NOAA,1988.
[12]WALDER J S,O?CONNOR J E.Methods for predicting peak discharge of floods caused by failure of natural and constructed earthen dams[J].Water Resources Research,1997,33(10):2 337-2 348.
[13]MACCHIONE F.Model for predicting floods due to earthen dam breaching.I:Formulation and evaluation[J].Journal of Hydraulic Engineering,2008,134(12):1 688-1 696.
[14]BELIKOV V V,VASIL?EVA E S,PRUDOVSKII A M.Numerical modeling of a breach wave through the dam at the Krasnodar reservoir[J].Power Technology and Engineering:formerly Hydrotechnical Construction,2010,44(4):269-278.
[15]MA H,FU X.Real time prediction approach for floods caused by failure of natural dams due to overtopping[J].Advances in Water Resources,2012,35:10-19.
[16]FAN X,TANG C X,VAN WESTEN C J,et al.Simulating dam-breach flood scenarios of the Tangjiashan landslide dam induced by the Wenchuan Earthquake[J].Natural Hazards and Earth System Sciences,2012,12(10):3 031-3 044.
[17]COLEMAN S E,ANDREWS D P,WEBBY M G.Overtopping Breaching of Noncohesive Homogeneous Embankments[J].Journal of Hydraulic Engineering,2002,128(9):829-838.
[18]MORRIS M W,HASSAN M,VASKINN K A,Breach formation:Field test and laboratory experiments[J].Journal of Hydraulic Research,2007,45(Supp.1):9-17
[19]LIU N,CHEN Z,ZHANG J X,et al.Draining the Tangjiashan barrier lake[J].Journal of Hydraulic Engineering,2010,136(11):914-923.
[20]DO X K,KIM M,NGUYEN H P T,et al.Analysis of landslide dam failure caused by overtopping[J].Procedia Engineering,2016,154:990-994.
[21]ZHU Y H,VISSER P J,VRIJLING J K,et al.Experimental investigation on breaching of embankments[J].Science China Technological Sciences,2011,54(1):148-155.
[22]SCHMOCKER L,HAGER W H.Modelling dike breaching due to overtopping[J].Journal of Hydraulic Research,2009,47(5):585-597.
[23]SCHMOCKER L,FRANK P J,HAGER W H.Overtopping dike-breach:effect of grain size distribution[J].Journal of Hydraulic Research,2014,52(4):559-564.
[24]CHANG D S,ZHANG L M.Simulation of the erosion process of landslide dams due to overtopping considering variations in soil erodibility along depth[J].Natural Hazards and Earth System Sciences,2010,10(4):933-946.