| Silt dam is a dam structure built for the purpose of retaining silt and silt in all levels of ditches in soil erosion areas.Water resources are scarce in Shanxi Province and soil is seriously weathered by nature.Soil and water conservation plays a vital role in the overall development of Shanxi Province.Water is the key restricting factor for many mountain people to go to a well-off society.In order to solve the problem of irrigation water use in impoverished mountainous areas,the idea of transforming large and medium-sized warping dams into small-sized retaining dams is put forward,and the seepage control and reinforcement are carried out to achieve the purpose of safe operation of water storage.Taking Sujiazhuang Silt Dam as a typical dam,this paper adopts two engineering measures and 24 anti-seepage reinforcement and transformation schemes for it.By means of numerical simulation,the anti-seepage effect of different engineering measures is analyzed,and a reasonable anti-seepage reinforcement and transformation scheme is put forward from the perspective of anti-seepage.The main research contents and conclusions are as follows:1.Through literature search,this paper reviews the common anti-seepage materials,engineering measures and seepage analysis methods of earth-rock dams,compares the design specifications of silt-fill dams and earth-rock dams,and analyses the technical problems needed to be solved when typical silt-fill dams are transformed into earth dams.2.Two engineering measures for seepage control and reinforcement of silt dams are put forward:?A?clay inclined wall is adopted in the upper reaches,and material thickness of original dam is strengthened in the lower reaches;?B?material thickness of original dam is adopted in the upper and lower reaches.At the same time,mattress drainage is adopted in the downstream of the dam body.According to the specific situation of Sujiazhuang silt dam,13 kinds of reconstruction schemes?scheme A1-A13?and 11 kinds of reconstruction schemes?scheme B1-B11?are proposed for engineering measure A and B respectively.3.Using numerical analysis method,two-dimensional steady seepage calculation is carried out for each scheme of the two engineering measures under the checked water level.The variation rules of dam body saturation line,isopotential line,outlet seepage ratio drop and single-width seepage flow are obtained,and the seepage control effects of different reconstruction schemes are analyzed.4.Upstream use of clay sloping wall,downstream use of original dam body material thickness,ie engineering measure A,anti-seepage reinforcement of typical dam:?1?From plan A1?upstream dam slope slope coefficient is 2.25,downstream dam slope slope coefficient is 2.0?to A13?upstream dam slope slope coefficient is 3.0,downstream dam slope slope coefficient is 2.75?,immersion line height As the upper and lower dam slope slopes increase,the height of the seepage escape point is about 88.1%lower than the dam before the transformation,and the minimum decrease is about 72.4%.From the plan A6?upstream dam slope side?The slope coefficient is 2.75,and the slope coefficient of the downstream dam slope is 2.0)to A13.As the slope coefficient of the upstream and downstream dam slopes continues to increase,the height of the immersion line is not significantly reduced.?2?The distribution trend of the equipotential lines of each scheme is relatively consistent,showing dense and dense distribution.Near the upstream dam foot,the equipotential line is densely distributed,then the distribution is relatively uniform,and finally it is denser near the foot of the downstream dam;compared with the dam before the transformation,the equipotential line in the dam is from the original dense and dense The distribution becomes dense and densely distributed;?3?In terms of export penetration ratio,the A1 plan has the largest outlet penetration ratio,which is 86.7%lower than that of the dam outlet before the transformation.The A13 scheme has the lowest export penetration ratio and the dam outlet penetration before the transformation.Compared with the drop,the decrease is 93.6%.From the aspect of single wide seepage flow,the single wide seepage flow of the A1 scheme is the largest,which is 3.7×10-6m3/s compared with the single wide seepage flow of the dam before the transformation.The single-filtration flow rate of the scheme is the smallest,which is 4.1×10-6m3/s compared with the single-wide seepage flow of the dam before the transformation;?4?As the slope coefficient of the upper and lower dam slopes gradually increases,the penetration ratio of the outlets of the schemes A1 to A13decreases gradually and is less than the allowable penetration ratio,and the variation of the inlet penetration ratio of the schemes A6 to A13 is less than 5%.The single-permeability flow rate changes within 2%,and the increase of the anti-seepage effect tends to be stable.5.The upper and lower reaches are both reinforced and reinforced with the original dam material,ie engineering measures B.?1?From Scheme B1?upstream dam slope slope coefficient is 2.5,downstream dam slope slope coefficient is 2.0?to B11?upstream dam slope slope coefficient is 3.0,downstream dam slope slope coefficient is 2.75?,with The coefficient of the slope of the downstream dam slope increases,and the height of the immersion line changes little.The height of the immersion line of each scheme is not significantly lower than that of the dam before the transformation;?2?The distribution trend of the equipotential lines of each scheme is relatively uniform,showing a sparse distribution.The distribution of equipotential lines from the upstream dam foot to the downstream dam foot dam gradually becomes denser.Compared with the dam before the transformation,the equipotential line distribution in the dam The change is not obvious;?3?In terms of outlet penetration ratio,the upstream dam slope slope coefficient is between 2.5-2.75,and the downstream dam slope slope coefficient between 2.0-2.75 is greater than the allowable osmotic ratio drop.The slope slope coefficient is 3.0,and the downstream inlet sloping ratio of the downstream dam slope slope coefficient between 2.0 and 2.75 is less than the allowable osmotic ratio drop;in the less than the allowable osmotic ratio drop,the B8 scheme has the largest outlet osmosis ratio.The B11 scheme has the lowest penetration ratio.Compared with the dam outlet penetration ratio before the transformation,the B8-B11 schemes vary by about 87%.From the single-wide seepage flow,the B1 scheme has the largest single-permeability flow,Compared with the single wide seepage flow of the dam before the transformation,the decrease is 1.0×10-6m3/s,and the single wide seepage flow of the B11 scheme is the smallest,which is reduced by 1.6×10-6m3/s compared with the single wide seepage flow of the dam before the transformation.;?4?From the schemes B1 to B11,as the slope coefficient of the upper and lower dam slopes gradually increases,the osmotic ratio of the dam outlet decreases gradually,and from the scheme B8?the upstream dam slope slope coefficient is 3.0,the downstream dam The slope slope coefficient is 2.0?to B11,the dam outlet permeability change is within 6%,and the single wide seepage flow is within 2%,indicating that when the dam slope increases to a certain value,the dam slope is slowed down again.The improvement in effect is not obvious.6.From the perspective of seepage prevention,the reference plan for seepage prevention and reinforcement of silt dam is proposed:the upstream inclined clay wall is used,and the slope coefficient of the dam slope is 2.75.The downstream dam body material is reinforced and thickened and sluice pad drainage is used.The slope factor is 2.0. |
PDF Full Text Request