Study On The Influence Of Impervious Geotechnical Material On The Seepage Of An Offshore And Estuarine Dam

There is a very long coastline in China, and a large number of offshore and estuarine dams has built. There is a close relationship between the common diseases of a dam and the seepage, so it is necessary to investigate the seepage characteristics of the offshore and estuarine dam. Impervious geotechnical material is widely used in practical engineering for its good soft feature and can adapt to dam’s deformation. By combing the indoor model test method and numerical analysis method, the influence of impervious geotechnical material on the seepage of an offshore and estuarine dam has been systematically studied in present thesis.By using a self-made model box, the seepage characteristics of a dam under a hydrostatic situation were carried out. Influences of the water head difference between upstream and downstream, the horizontal covering length of the impervious geotechnical material, the defect rate of the impervious geotechnical material on the seepage characteristics of a dam were investigated. Based on the experimental results, it is found that: The seepage discharge of unit width dam in unit time increases linearly with the water head difference between upstream and downstream. The hydrostatic pressure at a same level in the dam decreases linearly with the distance to dam’s foot. The seepage discharge of a dam decreases linearly with the horizontal covering length of the impervious geotechnical material. The influence of the horizontal covering length of the impervious geotechnical material on the change of the hydrostatic pressure at a same level in the dam is not obvious. Under the same conditions, the seepage discharge of a dam increases with the increasing defect rate of impervious geotechnical material. Besides, under the same conditions, the seepage discharge of a dam increases with the increasing defect diameter of impervious geotechnical material.By using a self-made model box, the seepage characteristics of a dam under a hydrodynamic situation were carried out. Influences of the wave frequency, the horizontal covering length of the impervious geotechnical material, the defect rate of the impervious geotechnical material on the seepage characteristics of a dam were investigated. Based on the experimental results, it is found that: The seepage discharge of unit width dam in unit time increases linearly with the frequency of the dynamic load. The seepage discharge of a dam decreases linearly with the horizontal covering length of the impervious geotechnical material. Under the same frequency, the seepage discharge of a dam increases with the increasing defect rate of impervious geotechnical material, and increases with the increasing defect diameter of impervious geotechnical material.Numerical analysis of the seepage characteristics of an offshore and estuarine dam was carried out. Based on the analysis for a hydrostatic situation, following conclusions has been drawn. The seepage discharge of unit width dam in unit time increases with the upstream water head. The seepage discharge of a dam decreases linearly with the horizontal covering length of the impervious geotechnical material. Under the same conditions, the larger the depth of the foundation is, the larger is the seepage discharge of a dam, and their relationships can be fitted as a polynomial expression. Comparing the seepages of a vertical curtain and a horizontal cover, it is found that, with the increasing of the impervious geotechnical material’s length, the anti seepage effect of the vertical curtain is better. Based on the analysis for a hydrodynamic situation, following conclusions has been drawn. For a same wave period, the larger the wave steepness is, the larger is the amplitude of the seepage discharge. For a same wave height, the seepage discharge has no connection with the wave steepness and the wave period. Under the same wave factors, with the increasing of the foundation’s water permeability, the change rate of the dam’s seepage velocity increases gradually. Besides, the influence of impervious geotechnical material on the seepage of a dam under a hydrodynamic situation is same as that of a hydrostatic situation.Both the hydrostatic situation and hydrodynamic situation were considered, the influence of impervious geotechnical material on the seepage of an offshore and estuarine dam had been carried out. The gained conclusions can provide a theoretical basis and technical support for the design, construction and operation management of an offshore and estuarine dam.