粘性泥石流阵性运动对沟床冲淤演变的影响--以云南东川蒋家沟为例

粘性泥石流沟床的冲淤具有其特殊的机理,年内及一场泥石流的沟床冲淤主要受泥石流体性质、流型、规模的控制,阵性运动中沟床演变主要反映在残留层厚度的变化。对云南东川蒋家沟进行野外现场泥石流及沟床冲淤的定位观测,应用观测资料对阵性粘性泥石流泥深、流速、拖曳力与沟床冲淤值的关系进行分析,认为在泥深<2.0m,流速<8m/s,流量<1500m3/s情况下,阵性泥石流运动前后沟床冲淤值与三者没有明显线性关系,沟床冲淤幅度较小,一般在-0.8~1.0m之间。通过分析,求得粘性泥石流沟床冲刷深度极限值的表达式。

The Influence of Discontinuous Motion of Viscous Debris Flow on Erosion and Deposition of Gully Bed--Study of the case at Jiangjia gully in Dongchuan, Yunnan

The characteristics of erosion and deposition of viscous debris flow gully bed are different from that of water flow or landslide. Gully bed of viscous debris flow exists with special mechanism,i.e.,scouring and silting of gully bed is mainly controlled by debris flow characteristics,flow type and scale among a year or once. Gully bed change during intermittent flow is mainly embodied by variety of depth of residual layer. Field observing debris flow at Jiangjia gully in Dongchuan City of Yunnan province and located observing of scouring and silting of gully bed were made. Gully bed evolution of observed section before and after intermittent flow passing through is measured by supersonic debris flow depth meter. According to field observed data, the relationship is analyzed among depth of viscous debris flow,velocity,drag force and scouring and silting of gully bed; as the debris flow depth is less than 2.0 m, velocity is less than 8.0 m/s ,and discharge is less than 1 500 m3/s. We can find that scouring and silting of gully bed doesn′t have obvious nonlinear relationship with above-mentioned three conditions and scale of scouring and silting of gully bed isn′t large, about between -0.8m and 1.0 m. According to the analysis, we attain the expression of gully bed′s maximum scouring depth of viscous debris flow. The equation has good physical meaning and it is correspondent to data in field.