Research On The Influence Of Seepage Field Changes Caused By The Rise And Fall Of Reservoir Water Level On The Stability Of Red Soil-type Reservoir Bank Slopes

In the course of the rise of the reservoir water level,the slope of the reservoir bank is divided into a floating weight area below the saturation line and a wet volume area above the saturation line.During the descent of the reservoir water level,the slope line and reservoir water level will divide the reservoir bank slope into the wet volume area above the saturation line,the saturation volume area between the saturation line and the reservoir level,and the floating volume area below the reservoir level.Therefore,along with the rise and fall of the reservoir water level,the stress of the reservoir bank slope is constantly redistributed,and the safety factor of the slope is constantly changing.At the same time,the osmotic pressure on the slope of the bank will also change as the water level of the reservoir changes.The bank slope stability will also be greatly affected by changes in the bank slope safety factor and the infiltration pressure.In order to analyze the influence of the change of seepage field caused by the rise and fall of reservoir water level on the bank slope stability,we first need to use the seepage calculation module in Geo-studio software to analyze the level and speed of the reservoir water level,the basic characteristics of red clay,and the bank slope shape.The influence of three factors on the seepage field.Then use the slope stability analysis module in Geo-studio software to analyze the influence of seepage field changes caused by these factors on slope stability.To this end,the following work is carried out in this paper:Firstly,this paper analyzes the effect of changes in red clay properties on the permeability coefficient from the soil dry density and initial moisture content.Then,using Geo-studio software to calculate the seepage flow of bank slopes with different characteristics of laterite,according to the change of pore water pressure,change of saturation line,and change of permeability gradient,the analysis of different dry density and initial moisture content on seepage field of bank slope The impact of osmotic pressure.The results show that:(1)When the reservoir water level rises to the highest point,the greater the red soil dry density and initial moisture content,the smaller the red clay permeability coefficient,the smaller the pore water pressure within the reservoir bank slope,and the greater the percolation pressure..(2)When the reservoir water level drops to the lowest point,the greater the dry density and initial moisture content of red soil,the greater the pore water pressure in the reservoir bank slope,and the greater the percolation pressure.(3)When the reservoir water level drops to the lowest point,the leading edge of the slope is the location where the osmosis damage is most likely to occur.Secondly,this paper calculates the seepage field of bank slope from two aspects,the level of reservoir water level rise and fall,and the analysis of the change of reservoir water level to the seepage field and seepage of reservoir bank slope according to the change of pore water pressure,the change of saturation line and the change of infiltration speed.The impact of pressure.The results showed that:(1)The phreatic line increased with the increase of reservoir water level and decreased with the decrease of reservoir water level,and the leaching line always lags behind the reservoir water level.When the reservoir water level rises to the highest point or falls to the lowest point,the hysteresis phenomenon is most obvious..And when the reservoir water level rises to the highest point or falls to the lowest point,the seepage pressure in the reservoir bank slope reaches its maximum value,and it is most prone to infiltration and destruction.(2)When the reservoir water level remains unchanged,the saturation line height in the bank slope will increase with time,and the seepage pressure on the bank slope will become smaller and smaller.(3)When the reservoir water level rises,the faster the reservoir water level rises,the smaller the pore water pressure in the bank slope is,and the greater the infiltration pressure.When the reservoir water level drops,the faster the water level of the reservoir drops,the more the pore water pressure in the reservoir bank slope increases,and the pressure of seepage pressure increases.Thirdly,this paper calculates the seepage field of reservoir bank slope from the slope height and slope ratio,and analyzes the bank slope shape change to the bank slope according to the change of pore water pressure,the change of the saturation line and the change of the percolation speed.Seepage field and the effect of osmotic pressure.The results show that:(1)The higher the bank slope height is,the larger the slope ratio is,and the larger the seepage pressure is,but the change is very small.(2)The pore water pressure in the bank slope is proportional to the slope height.The higher the slope,the greater the pore water pressure in the bank slope.(3)When the reservoir water level rises,the larger the slope ratio,the smaller the pore water pressure;when the reservoir water level decreases,the larger the slope ratio,the greater the pore water pressure inside the reservoir bank slope.Finally,by analyzing the influence of seepage field changes caused by various factors on the bank slope stability,the following conclusions can be drawn:(1)With the increase of the dry density of red clay,the bank slope safety factor and bank slope Permeation pressure will continue to increase.(2)When the reservoir water level rises,as the initial water content increases,the maximum value of the bank slope safety factor does not change significantly,but the infiltration pressure increases;when the reservoir water level decreases,the initial moisture content decreases.As the size of the bank slope increases,the minimum value of the bank slope safety factor will continue to decrease,while the infiltration pressure will continue to increase.(3)When the reservoir water level rises,the change of water pressure on the slope caused by the rise of reservoir water level is the main reason for the change of slope safety factor.In the impounding stage,the buoyancy force of the slider increases with time is the main reason that the safety factor of the slope becomes smaller continuously.When the water level of the reservoir decreases,the safety factor of the bank slope decreases first and then increases.(4)When the reservoir water level rises or the reservoir water level drops,the seepage pressure on the bank slope will increase,and when the reservoir water level rises to the highest point or falls to the lowest point,the infiltration pressure will be maximum.In addition,when the reservoir water level rises,the closer to the slope,the smaller the infiltration pressure;the lower the reservoir level,the closer to the slope,the greater the infiltration pressure.Therefore,the reservoir water level decline stage is the most likely stage of landslide.(5)When the bank slope safety factor reaches an extreme,the greater the slope height and slope ratio,the smaller the maximum and minimum slope safety factor.(6)The bank slope shape changes have little effect on the seepage pressure of bank slope.