Seepage And Stability Analysis Based On Fluid Solid Coupling Method

Warping dam is an important engineering measure of soil and water conservation,which is widely distributed in the Loess Plateau area with vertical and horizontal gullies and serious soil and water loss.It plays an important role in preventing soil and water loss.In addition,warping dam can promote the construction of ecological civilization,optimize the ecological environment and improve economic benefits.The soil and water conservation work in Shanxi Province has achieved fruitful results,and a large number of warping dams have been built.These warping dams are designed according to the routine,which do not meet the requirements of long-term water storage.Relying on the innovation project of the Department of water resources and aiming at solving the irrigation water consumption in the poor mountainous areas,the research group put forward the idea of transforming large and medium-sized warping dams into small retaining dams,and studied the key technical problems involved in transforming warping dams into storage dams.Combined with the engineering practice of two typical warping dams,He Jiazhuang warping dam and zhuershang backbone dam,this paper puts forward the concrete ideas of water storage reconstruction,sets up14 schemes of seepage prevention and reinforcement reconstruction,and uses the fluid solid coupling finite element method to calculate the seepage field and stress field,analyzes the advantages and disadvantages of each scheme from two aspects of seepage prevention and dam anti sliding stability,and recommends a reasonable optimization reconstruction scheme 。 The specific research contents and conclusions are as follows:1.The common anti-seepage engineering measures,seepage analysis and stability analysis methods of earth rock dam are reviewed,and the design specifications of warping dam and earth rock dam are compared.2.Considering the actual situation and economic factors of the project,three engineering measures are proposed for the seepage control and reinforcement of the warping dam:(A)the upstream and downstream dam slopes are thickened with the same materials as the dam body to slow down the upstream and downstream dam slopes;(B)the upstream dam slopes are consolidated with clay inclined walls,and the downstream dam slopes are maintained as they are;(C)the upstream dam slopes are paved with Geomembranes for the water storage.3.According to the specific situation of He Jiazhuang check dam,three measures(A,B and C)are used to set up six reconstruction schemes(A1,A2,B1-B3 and C1);according to the specific situation of Zuer upper main dam,eight schemes(A3-A8,B4 and C2)are set up.4.Considering the interaction between water pressure and soil stress,ABAQUS finite element software is used to establish the calculation model of fluid solid coupling and calculate the seepage field and stress field of each scheme,The seepage flow,saturation line,slip surface and safety factor of each scheme are analyzed.5.Adopt A,B and C measures to carry out anti-seepage and reinforcement transformation for He Jiazhuang check dam.The comparative analysis of each scheme shows that:(1)The seepage gradient at the outlet of the original He Jiazhuang check dam is higher than the allowable seepage gradient in the specification,which does not meet the seepage safety requirements;the safety factor is lower than the specification,which does not meet the dam stability safety requirements.If the He Jiazhuang check dam is to operate safely under the condition of water storage,it needs to carry out seepage prevention and reinforcement transformation.(2)Schemes A1 and A2 with the measures of slowing down the upstream slope and schemes b1-b3 with the clay inclined wall for seepage control and reinforcement at the upstream are all smaller than the allowable seepage gradient,and with the slowing down of the upstream dam slope,the seepage gradient at the outlet is gradually reduced,and the single width seepage flow is gradually reduced;scheme C1 with the composite geomembrane for seepage control improvement at the upstream is smaller than the allowable seepage gradient at the outlet The allowable permeability gradient meets the requirements of seepage safety,and the permeability gradient at the outlet of scheme C1 and the single wide permeability flow are greatly reduced.(3)The safety factors of schemes A1 and A2 are less than the specification requirements and do not meet the dam stability safety standard;when the upstream dam slope is impervious with clay inclined wall,the safety factors of schemes b1-b3 are greater than the specification requirements and meet the dam stability safety standard;when the upstream is impervious with composite geomembrane,the safety factors of scheme C1 meet the dam stability safety standard.The plastic strain of the original dam body and schemes A1 and A2 mainly occurs in the dam body,while that of schemes B1-B3 and C1 mainly occurs in the dam body and the upper half of the dam foundation.The plastic through area goes deep into the dam foundation,and the maximum plastic strain value is significantly larger,so the anti sliding effect of the dam body and the dam foundation is more obvious.(4)The seepage control scheme B1-B3 of clay inclined wall and C1 of composite geomembrane meet the seepage safety requirements and stability safety requirements,and the scheme is feasible.6.Adopt three measures A,B and C to carry out seepage prevention and reinforcement transformation for Zuer upper main dam:(1)The original seepage outlet seepage gradient of zuershang main dam is higher than the allowable seepage gradient in the specification,which does not meet the seepage safety requirements;the safety factor is lower than the specification,which does not meet the dam stability safety requirements.In order to ensure the safe operation of Zuer upper main dam under the condition of water storage,it is necessary to carry out seepage prevention and reinforcement.(2)The scheme a3-a7 with the measures of slowing down the dam slope is larger than the allowable seepage gradient,which does not meet the seepage safety requirements.The schemes A8,B4 and C2 are smaller than the allowable seepage gradient,which meets the seepage safety requirements.Compared with the original dam,the single width seepage flow of scheme A3-A8 is reduced;(3)The safety factors of scheme A3 are less than the specification requirements,which do not meet the safety requirements of dam stability;the safety factors of scheme A4-A8,B4 and C2 all meet the safety standards of dam stability;the distribution of plastic strain and the location of slip surface are similar to that of He Jiazhuang warping dam when the same reconstruction measures are adopted.(4)The scheme A8 of slowing down dam slope,the scheme B4 of clay inclined wall and the scheme C2 of composite geomembrane all meet the requirements of seepage safety and stability safety,and the scheme is feasible.7.The analysis shows that the engineering measures of laying geomembrane and clay inclined wall on the upstream slope of the original dam can achieve the purpose of water storage reconstruction.Considering the seepage control effect,the scheme of geomembrane is better.The specific measures to be adopted shall be considered in combination with local materials,economy and other factors.At the same time,the design scheme and size need to be combined with the specific warping dam for seepage and stability calculation and scheme optimization.The fluid structure coupling method used in this paper provides valuable reference for similar analysis and calculation.