堰塞体逐渐溃决数学模型研究

Research on mathematical model of gradual collapse of sputum

堰塞体是高位岸坡在地震作用下滑坡导致正常河道被堵塞而形成的天然堆石体。根据堰塞体溃决的特点采用有底坡明渠出流形式,结合冲刷率与速度平方成正比的关系建立堰塞体逐渐溃决数学模型。对“10·10”白格堰塞体溃决过程计算分析,结果表明:当冲刷系数α=0.0007~0.0009,糙率n=0.030~0.035时,溃决洪峰流量为8813.04~14087.49m 3/s之间,与实测值相比,洪峰流量误差在32%之内。当采用冲刷率与流速的平方成正比的冲刷方式时,建议冲刷模型系数α在0.0007~0.0009之间选取,可降低计算结果误差。增大泄流槽的糙率n,减少冲刷系数α,可以减少溃决洪峰流量,延缓洪峰流量出现时间。边坡角度θ对于洪峰出现时间、断面最大流速、洪峰流量大小影响都较小。

The dam body is a natural irregular dam formed by the high bank slope in the landslide caused by the earthquake,which causes the normal channel to be blocked.Combined with the characteristics of the dammed body collapse,the outflow pattern of the bottom slope open channel is used,and the mathematical model of the gradual collapse of the dam body is established based on the relationship between the scouring rate and the square of the velocity.Taking the 10·10 white grid collapse as an example,the calculation results show that when the erosion coefficientα=0.0007~0.0009,n=0.030~0.035,the peak flow rate is between 8813.04~14087.49m 3/s,compared with the measured value.The peak flow error is with in 32%.When the scouring method is used,the scouring rate is proportional to the square of the velocity.It is recommended that the scouring model coefficientαwas selected between 0.0007~0.0009,which can reduce the error of the calculation result.Increasing the roughness coefficient n of the drain groove and reducing the size of the flushing coefficientαcan reduce the peak flow rate and delay the occurrence of flood peak flow.The slope angleθhas little effect on the peak arrival time,the maximum flow velocity of the section,and the peak flow size.