Study On Seepage And Stability Of Flyash Dam For Electric Power Plant

Fly-ash dam as an important component of the electric power plant, its stability relations with the safety in production of electric power plant, the safety in people's life and property. Consequently, it is of great significance to analyse the seepage and stability of fly-ash dam.Depended on the intermediate investigation and stability evaluation project of TuJiaoGou fly-ash dam. The seepage and stability of the fly-ash dam for electric power plant have been studied synthetically by combining site investigation, in situ testing, laboratory tests, theoretical analysis and numerical simulation. The variation law of the seepage and stability field for fly-ash dam have been reached. It will provide guidance for engineering design of fly-ash dam treatment.In this paper, the main works and results are as follows:A detailed site investigation and in situ testing were taken, the engineering geological characteristics of the fly-ash dam have been comprehensively evaluated, the typical engineering geological profiles which can be used to seepage and stability analysis have been obtained, a great deal of physical and mechanical properties testing for the fly-ash and dam materials have been carried out, the physical parameters about fly ash and dam materials have been obtained. Testing results show that fly-ash material particle size distribution is more concentrated, graded poor and good permeability.Saturated-unsaturated seepage theory have been used, transient seepage with different time which retaining water before the fly-ash dam was analysed. Analysis results shows that the elevation of saturation line was relation with retaining water time before dam, dam material permeability and drainage facilities. Several factors of retaining water time before dam, long of dry bench, degree of blind ditch clogging, permeability of sloping wall, permeability of fly-ash, permeability of aeolotropism which impact the saturation line's law were studied. The results shows that with retaining water time before dam growth, the saturation line gradually elevate; with long of dry bench growth, the saturation line gradually reduce; with degree of blind ditch clogging growth, the saturation line gradually elevate; with permeability of sloping wall decrease, the saturation line gradually reduce; with permeability of fly-ash decrease, the saturation line gradually reduce; with permeability of aeolotropism decrease, the saturation line gradually reduce.Unsaturated soil slope stability analysis methods have been used, the stability of fly-ash dam was calculated, stability characters of dam slope with different conditions were reached. Through analysis, the factors which impact dam slope stability were retaining water time before dam, long of dry bench, strength of dam foundation soil, degree of blind ditch clogging, permeability of fly-ash, permeability of aeolotropism and permeability of sloping wall. The most notable factors were retaining water time before dam and long of dry bench, Secondly, the strength of dam foundation soil, Several other factors affect relatively small. There were two main reasons which arose fly-ash dam slide. The main reason is long-term retaining water time before dam, its made saturation line sharply heighten, soil bulk density augment, shear strength reduce. The secondly reason is blind ditch clogging, the saturation line elevation.Finite element method have been used, elastic-plastic finite element analysis was proceeded to fly-ash dam. In this calculation, ash-sluicing behind new dam which 150 meters distances to the fly-ash dam and retaining water before dam, but retaining water time is different were considered. The dam slope sliding process and mechanism were revealed. Finite element stress searching method was used to calculate stability of the dam slope in different time quantum. Analysis shows that with retaining water time before dam growth, the stability gradual attenuate, until failure.These research results of this paper have been successfully applied in XiangFan plant fly-ash dam project management, good technical and economic effects have been obtained, and it will be instructional to similar projects.