Research On Gradually Collapse Mechanism Of Reservoir Bank

Reservoir bank collapse is the most one of the discussion in the field of engineering geology, especially for the construction of large reservoirs and storage of the dam, which directly changes the original ecological geological environment of the reservoir area. With the rise of reservoir water level, the underground water level in the accumulation body is also rising. The reaction of water and rock soil gradually increase, accumulation soil’s strength reduce and lead to slope instability. Moreove, accumulation body in reservoir area influenced by water scouring, the scour action is mainly related to river flow and velocity of high and low water level. In this paper, the periodic fluctuation is defined as longitudinal erosion and flow of the high and low water level is defined as the transverse scour,research on mechanism of accumulation body in reservoir area influenced by the two erosions formed gradually Bank collapse.This article take the Hou Zhiyan Reservoir as the research region, summarized the internal factors of progressive bank collapse, the mechanism of progressive bank collapse under the action of reservoir water scouring is obtained by means of indoor physical simulation and numerical simulation. Through investigation, research and analysis, This paper mainly obtains the following results:1、Progressive collapse is that accumulation body in reservoir area influenced by periodical fluctuation of reservoir water level and external conditions does not occur the overall damage.It is a slowly destruction process with the time go by.2、The main factors that affect the progressive collapse include internal and external factors. Internal factors mainly include the material of composition, topography, permeability, slope angle. The external factor refers to the lateral erosion of reservoir water and the longitudinal scouring effect of water.3、Based on the investigation of accumulation body in Hou Zhiyan reservoir area.There are debris flow deposit, landslide deposit, residual deposit, collapse deposit.Most of deposit are good grading soil, few part of are poor grading.4、The vertical erosion is mainly through physical and chemical action of water on rock and soil, and reduce its strength. In addition, the periodic fluctuation of reservoir water makes the accumulation’s internal groundwater level change and due to pore water pressure change with reservoir water cycle change, the accumulation will slowly deformate. The greater the rate of change of reservoir water, the more prone to deformation and failure of the accumulation body. The transverse scour is mainly affected by the flow rate and the flow rate of the reservoir water. The flow rate and the size of the flow represent the strength of the water erosion. When the scour resistance of the accumulation body is less than that of the reservoir water, materials of accumulation will be transported away, scour cavity created. The upper accumulation body will lose the support and deformation finally.5、The progressive collapse is mainly affected by the longitudinal erosion under the periodic fluctuation of reservoir water in the study area. Lateral erosion is smaller, Mainly reason is the smaller flow rate in the study area, the transverse scour is mainly affected in the upper reaches of the reservoir area, before the river flow in the reservoir area has a high speed, when the river flows into the reservoir, speed down, So in the reservoir area, the influence of the lateral scouring on the reservoir bank reconstruction is small.6、In transverse scour process, when the flow rate is constant, the scour width with the the time go by will gradually tend to be stable, scour width different with different velocity. According to the analysis of the data, the final scour width and the velocity have a certain linear relationship with the different accumulation body slope angle, the larger slope angle, the smaller the slope of the linear equation. The relationship between reservoir water scour width with time and velocity satisfy the nonlinear regression equation is a and b is coefficient,that realated with the material composition, accumulation of permeability, slope angle, profile parameters; p is the maximum water velocity. x1 is the duration of the erosion, the value can tend to infinity with the hour as a unit, x2 is the velocity of flow.7、In the reservoir area, the width of the formation of water erosion is called the width of the base side. Bank collapse prediction method of slope structure with benchmark side etching width can be used to the Hou ziyan reservoir was improved in progressive type collapse formation.