格子坝拦挡黏性泥石流闭塞过程及其闭塞判识实验研究

Experimental study on characteristic of blocking process and blocking recognition of grid-type dam by viscous debris flow

坝体闭塞程度是透过型拦砂坝拦挡泥石流的重要特征之一,其决定着拦砂坝的拦挡效益。目前,对于格子坝拦挡黏性泥石流的设计还处在经验阶段,关于其闭塞类型和临界闭塞条件的研究较少,尚缺乏理论依据和技术指标,是泥石流防治工程设计急需解决的技术问题。通过室内水槽实验和理论分析,研究格子坝拦挡黏性泥石流闭塞过程及其闭塞判识方法。格子坝的闭塞主要受泥石流容重、格子坝开口间距与水槽坡度影响。格子坝拦挡黏性泥石流存在3种闭塞类型,即全闭塞类型、半闭塞类型、未闭塞类型。给出格子坝的闭塞临界综合判据F,实验结果表明,当F≤0.99时,格子坝表现为全闭塞类型;当0.99<F<2.92时,格子坝表现为半闭塞类型;当F≥2.92时,格子坝表现为未闭塞类型。同时,结合实验数据,提出格子坝闭塞度的定量计算的经验公式,可用于判识格子坝闭塞情况和格子坝开口间距设计提供依据,并举例说明判识公式的实用价值,可以进一步为实际工程应用提供技术支撑。

Blocking degree is one of the important features when open type check dam intercepts debris flow,which determines the debris flow control benefits of check dam.So far,the design of grid-type dam trapping viscous debris flow is still in the experience stage,and there are few research on blocking type and blocking criterion.There is no theoretical basis and technical index,which urgently needs to be solved for debris flow preventing engineering design.Through the flume experiment and theoretical analysis,we study the blocking process and blocking recognition of viscous debris flow by a grid-type dam.The degree of blocking was affected by bulk density of debris flow,grid size of dam and flume slope.There are three kinds of blocked types of grid-type dam for viscous debris flow,which are total-blocked type,part-blocked type and opening type.In this study,a critical comprehensive criterion(F)of blocking performance of grid-type dam is proposed.Experimental results show that when F≤0.99,the type of blocking is total-blocked type;when 0.99<F<2.92,the type of blocking is part-blocked type;when F≥2.92,the type of blocking is opening type.Finally,based on the experimental data,this paper presents the empirical formula for the quantitative calculation of the blocking degree of grid-type dam,which can be used to recognize blocking degree of grid-type dam and design of grid size of grid-type dam.And the practical value of the empirical formula is illustrated,which can provide the technical support for practical engineering applications further.