The Seepage Analysis Of Ash Reservoir Of Jilin Pypoelectricity Company

The seepage analysis of ash reservoir of JiLin pypoelectricity companyThe ash reservoir of ash-removing water conservancy is different from reservoir of the irrigation works, has its one's own characteristic.The general reservoir stores water, the ash reservoir drains off water. After the ash reservoir ran, water head of ash-water goes very high.Under the function of upstream and downstream pressure head, water of the reservoir is excreted to the low reaches in a large amount, cause the calamity of submerging to the low reaches, influence the economic development in week of the storehouse even threaten the security of resident's life seriously, cause the losses that hard to assess. So, how to drains off the leak water of the reservoir rationally, scientificly ,is an important subject in this kind of project, concern the economic benefits of the ash reservoir and the residents' security question directly of downstream.The paper has been analyzed the geology engineering condition and hydrogeologic condition of the Jilin pypoelectricity ash reservoir of nation power company in detail, clarified the infiltration mediums and infiltration law of the dam district, set up the three-dimensional influent model of dam district on this basis, utilized the visual module three-dimensional finite difference numerical calculation procedure Visual MODFLOW, under the water storage level situation of the two sub dams,carried out numerical modelling ,caculation and analyse to the groundwater influent of ash reservoir which added water drainage measure.(1)The paper has analysed the stratum structure of the researching area and infiltration characteristic of the groundwater, proposed the necessity of simulation of three-dimensional influent. The geological structure of dam district of the power company ash reservoir is comparatively complicated, the thickness of infiltration mediums is large, layer divided more and not even, the difference of water head of upstream and down stream is large, the three-dimensional characteristic of the influent is obvious.So, in order to delineate the influent space distribution once characteristic of dam district truly, it is necessary to study the numerical simulation of three-dimensional influent.(2)Through a large amount of infiltrating, pressing water and drawing water assay can know that the permeability coefficient of clay soil layer is much less then decencied moorstone layer, and can be found out in the result of calculation of three-dimensional influent simulation without the measure of drain off water, the seepage passway of the ash reservoir mainly centres in the dam site district, The groundwater mainly oozes out the reservoir area through decencied moorstone layer. Under the water storage level situation of the two sub dams, The amount of seepage collected of the Minzhu of north dam is respectively: 12004.17m~3 , 16722.56 m~3,Taojia is respectively: 3946.09 m~3 , 5406.46 m~3;Dalazi of south dam is respectively: 474.30 m~3,984.17m3。(3)The paper has been analyzed the geology engineering condition and hydrogeologic condition of the studying area in detail, clarified the infiltration mediums and infiltration law of the dam district, set up the hydrogeological conceptual models of the studying area.The whole researching district turns diving under water generally - moisture system of artesian water, the influent is according with the laminar flow of reaching the Darcy law, Calculation accorded to unsteady fluid flow and steady flow separately. Among,clay soil layer ,ash layer and strong decencied moorstone layer turn hole permeate mediums, weakly decencied moorstone layer turns an equivalent to permeate mediums generally continuously.(4)The paper deeply researched the seepage mediator and the seepage orderliness of the soil and rock mass in the research area. Considered the seepage mediator in research area contains pore seepage mediator, equivalent continuous mediator and crevice network discrete seepage mediator. When preset the permeability coefficient, clay soil layer ,ash layer and strong decencied moorstone layer is according to a large amount of infiltrating, pressing water and drawing water experiment outputs.Bedrock weakly weathered layer is according to the crevice rock mass permeability tensor theory.(5)On the basis that hydrogeological model and mathematical model were set up,the paper has adopted the visual module three-dimensional finite difference to divide the model Visual MODFLOW software into the groundwater flow and carried on the numerical simulation.After setting up the number value model of the three-dimensional influent well, in order to examine rationality and accuracy of the model, the paper carried on discernment and verification of the model.The paper calculated every part of the research area separately according to the groundwater undercurrent formula which reaches the Darcy law in the paper, under the water storage level situation of the two sub dams , to calculate the dam foundation the total flow is respectively 16424.56m~3/d,17603.40 m~3/d.And always oozing the flow under trying to get the same situation with the number value solution is respectively 23112.79 m~3/d,24688.08 m~3/d. The total flow is pretty much the same what is got analytic method and number value law solve, the relative error is respectively 7.70%,6.38%. Through examining, the model of simulation of law of number value is relatively close to reality, can describe the essential characteristic of the field of influent correctly and be used in different influent and control the influent field simulation under the scheme.(6)According to the analysis of the materials according to on-the-spot geological survey,and considering the geology engineering condition and hydrogeologic condition of the research area , and the mature experience of the water drainage measure of other ash reservoir engineering in Jilin, With the principle of safe, economic and logical, the paper chooses the scheme of assigning the pumping shaft equally. Under the water storage level situation of the two sub dams,using Visual MODFLOW to carry on the numerical simulation of three-dimensional influent to the design plan of water drainage,then the output of seepage discharge and flow field .(7)The paper compared and analysed the flow field of setting up pumping equipment and without umping equipment, and consulted the flow field in 1997 ,when the ash reservoir operated and did not cause the influence of submerging to downstream, verified the enforceability of the pumping equipment design plan,it would not cause the influence of submerging on the low reaches.(8) The Visual MODLOW of three-dimensional seepage numerical calculation program which is based on the finite difference calculus, now is become the standard specialty software system in the international, with it's characteristics such as visualization, systematization, and strong numerical simulation function. The paper uses the Visual MODFLOW in the three-dimensional seepage simulation and the seepage of drawing off design analysis, solves the practical problem in engineering very well, and got a good effect.