堰塞湖土料冲蚀特性测量系统研究

Research on measurement system of soil erosion characteristics for barrier lake study on the measurement system of the erosion characteristics of the earth material in the barrier lake

我国堰塞湖呈现大规模、高频率的趋势,一旦溃决,极易形成灾害链,威胁下游人民群众生命财产安全。冲蚀是堰塞湖溃决失稳的主要因素之一,定量分析冲蚀过程是揭示堰塞湖土料冲蚀特性的重要挑战。为定量测量堰塞湖土料的冲蚀特性,包括冲蚀剪应力和冲蚀率,本文研发了一种新的土料冲蚀特性测量系统。该测量系统包括圆筒型冲蚀试验设备(CETA)和冲蚀剪应力计算方法。CETA主要由结构系统、传动系统、冲蚀试验系统、清淤循环系统、控制和数据采集系统组成,用于测量冲蚀流速与冲蚀率之间的关系。针对易贡堰塞湖的单粒径土料开展了冲蚀试验,结果表明,该装置的冲蚀率试验可靠,与Briaud的实验结果一致,可用于分析冲蚀剪应力。提出了冲蚀剪应力的精确计算方法,建立了堰塞湖土料冲蚀率与冲蚀剪应力的双曲线冲蚀模型,为堰塞湖溃决洪水分析提供了技术参考。

In recent years,the barrier lakes in China have shown a trend of large-scale,high frequency,mass occurrence,and increasing risk.The barrier lake,if out of control,will pose a great threat to the downstream.Erosion is one of the main factors of landslide and instability of the barrier lake.A quantitative analysis of erosion process is an important challenge to revealing the erosion characteristics of dammed lake soil.To quantitatively measure the soil erosion characteristics of the barrier lake including the critical shear stress and the erosion rate,a new measurement system is proposed.The measurement system contains a cylindrical erosion test apparatus(CETA)and a method for calculating shearing stress.The CETA is designed to measure the relationship between the velocity and erosion rate,which is mainly composed of a structure system,a transmission system,an erosion test system,a desilting circulatory system,and a control and data acquisition system.By the proposed new method,single-size soil samples from the Yigong landslide-barrier dam-lake have been collected for erosion tests.It is noted that the erosion rate from the apparatus is reliable,which is at the same order as that of the experimental results by Briaud.This apparatus can be utilized to analyze the shear stress.The hyperbolic relationship between erosion rate and shear stress is found by proposing the accurate calculation method of shear stress,providing a technical reference for the analysis of dam break flood.