Study On Seepage Characteristics And Stability Of Tailings Dam With Internal Waste Rock Column

In this paper,a tailings dam in the south of China was taken as the research object,tailings were taken at different positions and depths at the top of the tailings dam,and waste rock were taken at the waste rock field.,a similar physical model(1:200)was established.A nalyzed the relationship between the seepage of unit time and grain graduation and center spacing of WRC,as well as the relationship between saturation line and grain graduation and center spacing of WRC under the mixed WRC-tailings sand.The U-tube groundwater level measurement system was used to measure the change of the head of each monitoring tube under different conditions.And studied the seepage field and stability of tailings dam by combing with numerical simulation.The results indicated:(1)The circle line of relationship between suction and volume rat e of water content shows the following results:The suction of tailings has weak effects on shear strength,if the volum rate of water conent of tailings is more than 15%.While in the condition that the volume rate of water content of tailings is near 20%,the dam will be safe mixed with tailings and waste rock.(2)The result of physical model researches that: with the declining number of fine particle content and increasing number of permeability coefficient of WRC,the unit rate seepage flow of the dam will followed with growing,while the saturation line decreases.(b)with the growing of the center distance,the unit rate seepage flow will declining,the saturation line will rise.(c)In the conditions of flood,the average height of the saturation line tailings dam is larger than the average of the normal conditions.Because the high level of impoundments water,and the velocity of water flow is ab ccelerating,which makes some parts of tailings attached to geo-textile and fine particles in porosity losing under the infiltration of groundwater in dam,as a result,permeability of WRC will increase.(3)Combined with numerical simulation,analyzed the saturation line uner different working conditions and different center spacing of WRC.The conclusion is in good agreement with the experimental results.It is found that the hydraulic slope increase near the starter dam toe by analyzing the slippage strip and safety system,it is suggested to strengthen the drainage measures at the bottom of the stater dam and the WRC,reinforcement and seepage preservation to the waste stone column next to the impoundment.With the decrease of the center spacing,the slip area decreases,the shear strength of slip bars decreases,and the safety factor increases gradually.With the increase of the width of WRC,the saturation line and safety factor of the dam increase slowly,but the center distance is the main factor affecting the change of the saturation line of the dam.(4)Hydraulic gradient increases at the slope toe of the starter dam and the edge of the WRC in the adjacent reservoir area,it is recommended to strengthen the drainage measures at the bottom of the starter dam and WRC.At the same time,the WRC closer to the impoundment,the higher of the depth of saturation line.Therefore,in actual engineering,should pay attention to the distance between the WRC and impoundment.