武都区群发性泥石流流速特征及堆积物粒度组成

Velocity characteristics and grain-size composition of grou Pdebris flow in Wudu District

2020年8月13—17日陇南市武都区发生了群发性泥石流灾害.在对这次群发性泥石流进行野外调查的基础上,利用Fudaa-LSPIV视频测速软件与经验公式估算了11条沟道中泥石流的平均流速,并分析了所调查的20条泥石流沟道中堆积物的粒度组成情况,采用标度分析法分析了各泥石流沟道内松散物堆积体的粒度特征并建立了流速V与标度分布参数μ与D c的线性回归模型.结果表明,本次群发泥石流的平均流速为2.57 m·s^(-1);泥石流固体堆积物的粒度分布不均匀,各泥石流粒度曲线主要呈现双峰形态;大部分泥石流沟堆积物的标度分布参数μ<0.05,特征粒径D c平均值为13.99 mm,这表明这次群发性泥石流大部分为高容重、粘性泥石流.通过分析容重、参数μ和D c与平均流速之间的关系,可知参数μ与平均流速呈现正相关关系,特征粒径D c、容重与平均流速之间均呈负相关关系,流速与参数μ和D c均呈多元线性相关关系,从而在泥石流流速与泥石流堆积物粒度参数之间建立了联系.

The grouPdebris flow disasters broke out from August 13 to 17,2020 in Wudu District,Longnan City.Based on filed investigation in Wudu District,average flow velocities of debris flow in 11 gullies were estimated by using Fudaa-LSPIV video velocity measurement software and empirical formula,particle size analyses were carried out on field samples of debris flow deposits in 20 gullies,grain size characteristics of loose deposits in each gully were analyzed with general form method,and the linear regression models of velocity V and grain size parametersμand D c were established.Results indicate that the average flow velocity of debris flow in each gully is 2.57 m·s^(-1);the grain size distribution of solid deposits in debris flow is not uniform,and the grain size curve of debris flow in each gully is mainly bimodal;for most gully deposits,the grain size distribution parameterμ<0.05 and the mean value of the characteristic particle size D c is 13.99 mm,which shows that most of the debris flows in the gullies are high bulk density and viscous debris flows.By establishing the relationshiPbetween bulk density,parameterμ,D c and velocity respectively,it can be found that the parameterμand velocity are positively correlated,while the characteristic particle size D c and bulk density are negatively correlated with velocity,and velocity and parameterμand D c are multivariate linear correlated.