Mesoscopic Study Of Relief Wells Silting And Recovery Mechanism

Relief Wells’ normal run efficiently on safety and stability of the dam project has great significance. Engineering practice shows that lower underground water level after dam to improve the stability of project is significant. The relief well is an important means of seepage control. It using groundwater seepage characteristics after the dam, can drain off confined water, reduce the water level. But relief Wells’ siltation problem greatly affected the running effect of relief Wells. Therefore, to research the relief Wells’ siltation mechanism, and explore an effective siltation recovery measures, can provide theoretical basis and technical support for the relief well continue to run efficiently.In this paper, using theoretical analysis and numerical simulation methods, reveal relief well siltation characteristic and recovery measures. The main research was carried out by the following aspects:(1)Groundwater seepage model is established by two-dimensional seepage calculation software UNSST2. On the relief well spacing, hole diameter, outlet elevation, penetration depth and filter layer permeability factors run the simulated computation. Analyzing operation way and the law of every influence factor on the effect of relief Wells. Penetration depth and filter layer permeability have significantly effect on the running performance;Outlet elevation also has certain influence;Well diameter and well spacing have little influence.(2)Summarizes the existing conclusions and calculated results, analyzing machinery siltation, chemical siltation and biology siltation. Machinery siltation is that groundwater move fine particles to around wells, coupled with intermittent operation characteristics of wells, give rise to a large number of fine particles store around wells; Chemical siltation is that chemical substances is transported to wells by groundwater, react with oxygen, generate condensate cause siltation; Biological siltation is that the biological activity around wells cause siltation.(3)The three dimensional seepage model of relief Wells was established based on 3 d seepage calculation software UNSS3, to calculate the seepage slope of filter layer in the process of deep drawdown. Through deep drawdown to get large enough seepage slope, to break the siltation, make the fine particle run off.(4)Through spot experiment and the analysis of many years observation data, explore the effect of the way of deep drawdown and cycle repeats wash well. This method has significant effect, most of the effect of relief well which is clogged is significantly increased by this way. The material of well casing has biggish effect on this way.