非匀质泥石流运动特征与峰值流量关系研究

RELATIONSHIP BETWEEN MOVEMENT CHARACTERISTICS OF NONHOMOGENEOUS DEBRIS FLOW AND PEAK FLOW

对非匀质泥石流运动变化特征进行预测评价是泥石流防治工程规划和预警预报系统建设的重要内容,也是目前泥石流领域亟需完善的重点问题。通过对泥石流泥位和流速实测资料整理和分析,构建了非匀质泥石流运动特征值预测模型,该模型在前人成果的基础上,利用较少因子就能够判别研究区泥石流运动变化特征,并以陇南地区礼县下胡杨沟泥石流为例,通过FLO-2D流体模型对50年一遇(2%频率)和20年一遇(5%频率)降水条件下泥石流运动特征进行模拟。结果表明泥石流容重为1.83 t·m-3时,下胡杨沟20年一遇的泥石流运动特征值最小且差异性不大;当泥石流容重为1.97 t·m-3时,下胡杨沟50年一遇的泥石流运动特征值最大且差异性悬殊;当不同规模泥石流流量达到峰值时均产生较大的泥位深度。进一步将泥石流运动特征值模拟结果与实测断面相结合检验分析,并反推已发生泥石流事件的峰值流量,与实际情况都具有较好的一致性,表明采用本文预测模型计算的结果具有一定的可靠性,可为泥石流防灾减灾和泥石流监测预警示范区建设提供参考。

The prediction and evaluation of the change characteristics of non-homogeneous debris flow are an important content of debris flow control project planning and early warning and forecasting system construction.They are also a key issue that needs to be improved in the field of debris flow.By sorting out and analyzing the measured data of the mud level and velocity of the debris flow,a prediction model of the characteristic value of the nonhomogeneous debris flow movement is constructed.Based on the previous results,the model can distinguish the change characteristics of the debris flow movement in the study area with fewer factors.Taking the mud-rock flow in Xiahuyang Gully,Lixian County,Longnan area as an example,the FLO-2 D fluid model is used to simulate the movement characteristics of debris flow under precipitation conditions of once in 50 years(2%frequency)and once in 20 years(5%frequency).The results show that when the specific weight gravity of debris flow is 1.83 t·m-3,the characteristic value of debris flow movement in Xiahuyang Gully in 20 years is the smallest and the difference is not significant.When the specific weight gravity of debris flow is 1.97 t·m-3,the characteristic value of debris flow movement in Xiahuyang Gully is once in 50 years the biggest and the difference is huge.When the flow of debris flows of different scales reaches the peak,they all produce larger mud level depth.The simulation results of the debris flow movement characteristic value are further combined with the actual measured cross-sections for inspection and analysis.The peak flow rate of the debris flow event is inferred and is in good agreement with the actual situation,indicating that the results calculated by the prediction model of this paper are reliable.The results in this paper can provide a reference for the construction of debris flow disaster prevention and mitigation and debris flow monitoring and early warning demonstration areas.