滑坡碎屑流冲击拦挡结构的离散元模拟
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摘要
拦挡结构可以有效减小滑坡致灾范围、减弱致灾强度。文章以滑坡碎屑流为研究对象,通过对比模型试验和数值模拟结果,校正三维离散元模拟参数,进而研究不同坡脚角度和挡板高度对冲击力、最大水平运动距离的影响。研究结果表明:三个坡脚角度碎屑流冲击力的变化过程存在明显区别,坡脚角度为35°和45°时,冲击力时程曲线经历了两个显著的变化阶段:线性增大、线性减小。而坡脚角度为55°时,碎屑流冲击力时程曲线出现三个变化阶段:线性增加、恒力阶段、线性减小。挡板高度越高,恒力阶段的持续时间越短,冲击力线性减小阶段时间越长。小颗粒(2.5～10 mm)对挡板的冲击效应显著;中等颗粒(10～25 mm)随着挡板高度的增加,对挡板的冲击效应逐渐增大;而大颗粒(25～60 mm)作用在挡板上的冲击效应出现突变,与其他两种颗粒对比,整个运动过程冲击效应不显著。碎屑流的运程随着挡板高度的增加逐渐减小。对比三个坡脚角度下挡板的拦挡效果,坡脚角度α≤45°时,拦挡效果显著。
Construction of resistive structures can effectively reduce the deposit area of landslides and weaken the intensity of hazard.In this study,the landslide-debris flow is examined by using the 3D discrete element method,whose parameters are calibrated by comparing the results of the model tests and those of the numerical simulations.The influence of different slope gradients and the height of barrier on the impact force and the maximum of the horizontal running distance are further studied.The results indicate that for the three experiments with different slope gradients there are obvious differences in the impact force variation processes.When the slope gradient is 35° or 45°,the magnitude of the landslide-debris flow impact force undergoes two significant stages:linear increase and linear decrease.When the gradient is 55°,there are three stages of change in the time-history curve:linear increase,constant force stage and linear decrease.The higher the height of barrier is,the shorter the time duration of the constant force stage,and the longer the linear decrease stage is.Small particles(2.5～10 mm) have significant impact effects on the barrier.With the increasingheight of barrier,the impact effect of the medium particles(10～25 mm) on the barrier gradually increases.The impact effect of large particles(25～60 mm) on the barrier has an abrupt change.Compared with other two kinds of particles,this impact effect is not significant during the whole motion.The running distance of the landslide-debris flow gradually decreases with the increasing height of barrier.Comparison of the resistance effects of the barrier under three slope gradients shows that the resistance effect is significant when the slope gradient α≤45°.
Construction of resistive structures can effectively reduce the deposit area of landslides and weaken the intensity of hazard.In this study,the landslide-debris flow is examined by using the 3D discrete element method,whose parameters are calibrated by comparing the results of the model tests and those of the numerical simulations.The influence of different slope gradients and the height of barrier on the impact force and the maximum of the horizontal running distance are further studied.The results indicate that for the three experiments with different slope gradients there are obvious differences in the impact force variation processes.When the slope gradient is 35° or 45°,the magnitude of the landslide-debris flow impact force undergoes two significant stages:linear increase and linear decrease.When the gradient is 55°,there are three stages of change in the time-history curve:linear increase,constant force stage and linear decrease.The higher the height of barrier is,the shorter the time duration of the constant force stage,and the longer the linear decrease stage is.Small particles(2.5～10 mm) have significant impact effects on the barrier.With the increasingheight of barrier,the impact effect of the medium particles(10～25 mm) on the barrier gradually increases.The impact effect of large particles(25～60 mm) on the barrier has an abrupt change.Compared with other two kinds of particles,this impact effect is not significant during the whole motion.The running distance of the landslide-debris flow gradually decreases with the increasing height of barrier.Comparison of the resistance effects of the barrier under three slope gradients shows that the resistance effect is significant when the slope gradient α≤45°.
引文
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[16]袁小一,许强,程谦恭,等.高速远程滑坡-碎屑流超前冲击气浪分析[J].水文地质工程地质,2016,43(6):113-119.[YUAN X Y,XU Q,CHENG Q G,et al.An analysis of air-blasts induced by rock avalanche[J].Hydrogeology&Engineer-ing Geology,2016,43(6):113-119.(in Chinese)]
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[2]刘传正.深圳红坳弃土场滑坡灾难成因分析[J].中国地质灾害与防治学报,2016,27(1):1-5.[LIU C Z.Genetic mechanism of landslide tragedy happened in Hong'ao dumping place in Shenzhen,China[J].The Chinese Journal of Geological Hazard and Control,2016,27(1):1-5.(in Chinese)]
[3]杨海龙,樊晓一,赵运会,等.偏转角度对滑坡-碎屑流运动影响的模型试验[J].山地学报,2017,35(3):316-322.[YANG H L,FAN X Y,ZHAO Y H,et al.Model tests on influence of deflection angle on the movement of landslide-debris avalanches[J].Mountain Research,2017,35(3):316-322.(in Chinese)]
[4]宋东峰,程兴军.贵阳海马冲“5·20”山体滑坡排险[J].人民长江,2016,47(11):5-9.[SONG D F,CHENG X J.Danger removal of“5.20”mountainous landslide at Mahaichong,Guiyang[J].Yangtze River,2016,47(11):5-9.(in Chinese)]
[5]甘建军,樊俊辉,唐春,等.浙江遂昌苏村滑坡基本特征与成因机理分析[J].灾害学,2017,32(4):73-78.[GAN J J,FAN J H,TANG C,et al.Sucun landslide in Suichang County of Zhejiang Province:characteristics and failure mechanism[J].Journal of Catastrophology,2017,32(4):73-78.(in Chinese)]
[6]吴越,刘东升,李明军.岩体滑坡冲击能计算及受灾体易损性定量评估[J].岩石力学与工程学报,2011,30(5):901-909.[WU Y,LIU D S,LI M J.Impact energy calculation for rock slope and quantitative assessment of vulnerability for element at risk[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(5):901-909.(in Chinese)]
[7]吴越,刘东升,李明军.滑体下滑及冲击受灾体过程中的能耗规律模型试验[J].岩石力学与工程学报,2011,30(4):693-701.[WU Y,LIU D S,LI MJ.Landslide model experiment for energy dissipation law in sliding and impact processes[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(4):693-701.(in Chinese)]
[8]段晓冬,樊晓一,姜元俊,等.碎屑流冲击挡墙的土拱效应研究[J].自然灾害学报,2015,24(5):92-102.[DUAN X D,FAN X Y,JIANG Y J,et al.Study on soil arch effect of dry debris flow for impact barricade wall[J].Journal of natural disasters,2015,24(5):92-102.(in Chinese)]
[9]C W W NG,C E CHOI.Physical modeling of baffles influence on landslide debris mobility[J].Original Paper,2014:1-18.
[10]樊赟赟,王恩志,王思敬.碎屑流运动模拟及能量过程研究[J].东北大学学报(自然科学版),2011,32(9):1344-1347.[FAN Y Y,WANG E Z,WANGS J.Motion simulation of debris flow and research on energy process[J].Journal of Northeastern University(Natural Science),2011,32(9):1344-1347.(in Chinese)]
[11]SALCIARINI D,TAMAGNINI C,CONVERSINI P.Discrete element modeling of debris-avalanche impact on earthfill barriers[J].Physics and Chemistry of the Earth:Parts A/B/C,2010,35(3/4/5):172-181.
[12]孙新坡,何思明,樊晓一,等.崩塌体与拦石墙冲击动力演化过程及参数敏感性[J].成都理工大学学报(自然科学版),2017,44(2):232-238.[SUN XP,HE S M,FAN X Y,et al.The impact dynamic evolution process and parameter sensitivity study on collapse and buttress[J].Journal of Chengdu University of Technology(Science&Technology Edition),2017,44(2):232-238.(in Chinese)]
[13]JIANG Y J,TOWHATA I.Experimental study of dry granular flow and impact behavior against a rigid retaining wall[J].Rock Mechanics&Rock Engineering,2013,46(4):713-729.
[14]JIANG Y J,ZHAO Y.Experimental investigation of dry granular flow impact via both normal and tangential force measurements[J].Geotechnique Letters,2015,5(January-March):33-38.
[15]JIANG Y J,ZHAO Y,TOWHATA I,et al.Influence of particle characteristics on impact event of dry granular flow[J].Powder Technology,2015,270:53-67.
[16]袁小一,许强,程谦恭,等.高速远程滑坡-碎屑流超前冲击气浪分析[J].水文地质工程地质,2016,43(6):113-119.[YUAN X Y,XU Q,CHENG Q G,et al.An analysis of air-blasts induced by rock avalanche[J].Hydrogeology&Engineer-ing Geology,2016,43(6):113-119.(in Chinese)]
[17]杨海龙.沟谷偏转型滑坡-碎屑流运动机理研究[D].绵阳:西南科技大学,2018.[YANG H L.Movement mechanism of turning-type landslide debris flow in valley topography[D].Mianyang:Southwest University of Science and Technology,2018.(in Chinese)]
[18]JIANG Y J,WANG Z Z,SONG Y,et al.Cushion layer effect on the impact of a dry granular flow against a curved rock shed[J].Rock Mechanics&Rock Engineering,2018,51(7):2191-2205.