泥石流对桥墩冲击力的试验研究
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摘要
泥石流冲毁桥墩是桥梁在遭受泥石流冲击时的常见破坏形式。为了研究泥石流对桥墩的冲击力大小,通过调整黏土、沙、石子、水的不同含量,配置不同流变特性、不同密度的泥石流,使用所配置的原料在泥石流槽内对两种形状(圆形、方形)的桥墩缩尺模型进行冲击,综合考察了流变特性、流速、桥墩形状以及冲击力的关系。试验表明:试验配置的泥石流原料流变特性差异明显,且可以用简单的选择流变仪测得,用牛顿流体或宾汉体描述。泥石流的流速可用曼宁公式求得,而公式中的糙率系数与泥石流黏度满足幂函数关系。相同工况下,不同形状桥墩所受的冲击力差异明显,方形桥墩阻力系数普遍大于圆形桥墩。使用非牛顿流体雷诺数(Re)可以综合反映流变特性和流速,因此,圆墩的阻力系数可表达为Re的函数,而方墩则没有明显关系。为方便工程应用,可根据黏性泥石流、稀性泥石流对圆墩的阻力系数分别为2.3、0.9,对方墩分别为2.6、1.9进行选用。
Debris flow destroying piers is a common destructive form of bridge under the impact of debris flow. To investigate the magnitude of debris flow impact forces on bridge piers, we adjusted the contents of clay, sand, gravel, and water to generate debris flows with different rheological properties and densities. Two types of pier scale models with circular and square cross section were impacted in debris flow trough by using the above debris flows to comprehensively investigate the relationship between rheological characteristics, flow velocity, pier shape and impact force. The results show that the obtained debris flow materials have distinct rheological properties which can be easily measured through a rotational viscometer and represented by Newtonian fluid or Bingham fluid. The velocity of debris flow can be calculated by the Manning equation, and the roughness coefficient and the viscosity of debris flow in the equation satisfy a power function relationship. In the same cases, the impact forces on a round pier and on a square pier are significantly different. Generally, the drag coefficient of impact force on a round pier is much larger than that on a square pier. Because using non-Newtonian fluid Reynolds number(Re) can comprehensively represent the debris flow's rheological properties and velocities, the drag coefficient of the round pier be expressed as a function of Re. However, there exists this function for the square pier. For the convenient application in engineering, the drag coefficient of a round pier can be selected as 2.3 and 0.9 for viscous debris flow and sub-viscous debris flow, respectively. For a round pier, the drag coefficients are 2.6 and 1.9 for viscous debris flow and sub-viscous debris flow, respectively.
Debris flow destroying piers is a common destructive form of bridge under the impact of debris flow. To investigate the magnitude of debris flow impact forces on bridge piers, we adjusted the contents of clay, sand, gravel, and water to generate debris flows with different rheological properties and densities. Two types of pier scale models with circular and square cross section were impacted in debris flow trough by using the above debris flows to comprehensively investigate the relationship between rheological characteristics, flow velocity, pier shape and impact force. The results show that the obtained debris flow materials have distinct rheological properties which can be easily measured through a rotational viscometer and represented by Newtonian fluid or Bingham fluid. The velocity of debris flow can be calculated by the Manning equation, and the roughness coefficient and the viscosity of debris flow in the equation satisfy a power function relationship. In the same cases, the impact forces on a round pier and on a square pier are significantly different. Generally, the drag coefficient of impact force on a round pier is much larger than that on a square pier. Because using non-Newtonian fluid Reynolds number(Re) can comprehensively represent the debris flow's rheological properties and velocities, the drag coefficient of the round pier be expressed as a function of Re. However, there exists this function for the square pier. For the convenient application in engineering, the drag coefficient of a round pier can be selected as 2.3 and 0.9 for viscous debris flow and sub-viscous debris flow, respectively. For a round pier, the drag coefficients are 2.6 and 1.9 for viscous debris flow and sub-viscous debris flow, respectively.
引文
[1]王林峰,唐红梅,陈洪凯.泥石流区桥墩损毁机制与控制研究[J].防灾减灾工程学报,2012,32(3):353-358.WANG Lin-feng,TANG Hong-mei,CHEN Hong-kai.Study on the mechanism of pier’s destruction and control in the active debris flow regions[J].Journal of Disaster Prevention and Mitigation Engineering,2012,32(3):353-358.
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[3]何思明,吴永,沈均.泥石流大块石冲击力的简化计算[J].自然灾害学报,2009,18(5):51-56.HE Si-ming,WU Yong,SHEN Jun.Simplified calculation of impact force of massive stone in debris flow[J].Journal of Natural Disasters,2009,18(5):51-56.
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[6]HU K,WEI F,LI Y.Real-time measurement and preliminary analysis of debris-flow impact force at Jiangjia Ravine,China[J].Earth Surface Processes and Landforms,2011,36(9):1268-1278.
[7]朱兴华,崔鹏,唐金波,等.黏性泥石流流速计算方法[J].泥沙研究,2013,(3):59-64.ZHU Xing-hua,CUI Peng,TANG Jin-bo,et al.Acalculation method for the velocity of viscous debris flow[J].Journal of Sediment Research,2013,(3):59-64.
[8]SHIEH C,TING C,PAN H.Impulsive force of debris flow on a curved dam[J].International Journal of Sediment Research,2008,23(2):149-158.
[9]ARMANINI A,LARCHE M,ODORIZZI M.Dynamic impact of a debris flow front against a vertical wall[C]//Proceedings of the 5th International Conference on Debris-Flow Hazards Mitigation:Mechanics,Prediction and Assessment.Roma,Italy:Sapienza University of Rome,2011:1041-1049.
[10]何晓英,唐红梅,陈洪凯.浆体黏度和级配颗粒组合条件下泥石流冲击特性模型试验[J].岩土工程学报,2014,36(5):977-982.HE Xiao-ying,TANG Hong-mei,CHEN Hong-kai.Experimental study on impacting characteristic of debris flow considering different slurry viscosities,solid phase ratios and grain diameters[J].Chinese Journal of Geotechnical Engineering,2014,36(5):977-982.
[11]IVERSON R M,LOGAN M,LAHUSEN R G,et al.The perfect debris flow?Aggregated results from 28large-scale experiments[J].Journal of Geophysical Research,2010,115(F3).DOI:10.1029/2009JF001514.
[12]陈兴长,陈慧,游勇,等.泥石流拦砂坝底扬压力分布及影响因素试验[J].岩土力学,2018,39(9):3229-3236.CHEN Xing-chang,CHEN Hui,YOU Yong,et al.Experiment on distribution and influence factors of uplift pressure acting on bottom of debris flow check dam[J].Rock and Soil Mechanics,2018,39(9):3229-3236.
[13]费祥俊,舒安平.泥石流运动机理与灾害防治[M].北京:清华大学出版社,2004.FEI Xiang-jun,SHU An-ping.Movement mechanism and disaster control for debris flow[M].Beijing:Tsinghua University Press,2004.
[14]ASTM.D2196―15 Standard test methods for rheological properties of non-Newtonian materials by rotational viscometer[S].West Conshohocken,United States:[s.n.],2015.
[15]何晓英.浆体与级配颗粒组合条件下泥石流冲击特性实验研究[D].重庆:重庆交通大学,2014.HE Xiao-ying.Experimental study on the shock characteristics of debris flow considering different slurry viscosity and gradation particles[D].Chongqing:Chongqing Jiaotong University,2014.
[16]ZAKERI A,HOEG K,NADIM F.Submarine debris flow impact on pipelines.Part I:Experimental investigation[J].Coastal Engineering,2008,55(12):1209-1218.
[17]四川省国土资源厅.DZ/T 0220―2006泥石流灾害防治工程勘查规范[S].北京:中国标准出版社,2006.Department of Land and Resources of Sichuan Province.DZ/T 0220―2006 Specification of geological investigation for debris flow stabilization[S].Beijing:Standards Press of China,2006.
[2]胡凯衡,崔鹏,葛永刚.舟曲“8.8”特大泥石流对建筑物的破坏方式[J].山地学报,2012,30(4):484-490.HU Kai-heng,CUI Peng,GE Yong-gang.Building destruction patterns by August 8,2010 debris flow in Zhouqu,Western China[J].Journal of Mountain Science,2012,30(4):484-490.
[3]何思明,吴永,沈均.泥石流大块石冲击力的简化计算[J].自然灾害学报,2009,18(5):51-56.HE Si-ming,WU Yong,SHEN Jun.Simplified calculation of impact force of massive stone in debris flow[J].Journal of Natural Disasters,2009,18(5):51-56.
[4]ZHANG S.A comprehensive approach to the observation and prevention of debris flows in China[J].Natural Hazards,1993,7(1):1-23.
[5]唐金波,胡凯衡,周公旦,等.基于小波分析的泥石流冲击力信号处理[J].四川大学学报(工程科学版),2013,45(1):8-13.TANG Jin-bo,HU Kai-heng,ZHOU Gong-dan,et al.Debris flow impact pressure signal processing by the wavelet analysis[J].Journal of Sichuan University(Engineering Science Edition),2013,45(1):8-13.
[6]HU K,WEI F,LI Y.Real-time measurement and preliminary analysis of debris-flow impact force at Jiangjia Ravine,China[J].Earth Surface Processes and Landforms,2011,36(9):1268-1278.
[7]朱兴华,崔鹏,唐金波,等.黏性泥石流流速计算方法[J].泥沙研究,2013,(3):59-64.ZHU Xing-hua,CUI Peng,TANG Jin-bo,et al.Acalculation method for the velocity of viscous debris flow[J].Journal of Sediment Research,2013,(3):59-64.
[8]SHIEH C,TING C,PAN H.Impulsive force of debris flow on a curved dam[J].International Journal of Sediment Research,2008,23(2):149-158.
[9]ARMANINI A,LARCHE M,ODORIZZI M.Dynamic impact of a debris flow front against a vertical wall[C]//Proceedings of the 5th International Conference on Debris-Flow Hazards Mitigation:Mechanics,Prediction and Assessment.Roma,Italy:Sapienza University of Rome,2011:1041-1049.
[10]何晓英,唐红梅,陈洪凯.浆体黏度和级配颗粒组合条件下泥石流冲击特性模型试验[J].岩土工程学报,2014,36(5):977-982.HE Xiao-ying,TANG Hong-mei,CHEN Hong-kai.Experimental study on impacting characteristic of debris flow considering different slurry viscosities,solid phase ratios and grain diameters[J].Chinese Journal of Geotechnical Engineering,2014,36(5):977-982.
[11]IVERSON R M,LOGAN M,LAHUSEN R G,et al.The perfect debris flow?Aggregated results from 28large-scale experiments[J].Journal of Geophysical Research,2010,115(F3).DOI:10.1029/2009JF001514.
[12]陈兴长,陈慧,游勇,等.泥石流拦砂坝底扬压力分布及影响因素试验[J].岩土力学,2018,39(9):3229-3236.CHEN Xing-chang,CHEN Hui,YOU Yong,et al.Experiment on distribution and influence factors of uplift pressure acting on bottom of debris flow check dam[J].Rock and Soil Mechanics,2018,39(9):3229-3236.
[13]费祥俊,舒安平.泥石流运动机理与灾害防治[M].北京:清华大学出版社,2004.FEI Xiang-jun,SHU An-ping.Movement mechanism and disaster control for debris flow[M].Beijing:Tsinghua University Press,2004.
[14]ASTM.D2196―15 Standard test methods for rheological properties of non-Newtonian materials by rotational viscometer[S].West Conshohocken,United States:[s.n.],2015.
[15]何晓英.浆体与级配颗粒组合条件下泥石流冲击特性实验研究[D].重庆:重庆交通大学,2014.HE Xiao-ying.Experimental study on the shock characteristics of debris flow considering different slurry viscosity and gradation particles[D].Chongqing:Chongqing Jiaotong University,2014.
[16]ZAKERI A,HOEG K,NADIM F.Submarine debris flow impact on pipelines.Part I:Experimental investigation[J].Coastal Engineering,2008,55(12):1209-1218.
[17]四川省国土资源厅.DZ/T 0220―2006泥石流灾害防治工程勘查规范[S].北京:中国标准出版社,2006.Department of Land and Resources of Sichuan Province.DZ/T 0220―2006 Specification of geological investigation for debris flow stabilization[S].Beijing:Standards Press of China,2006.
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