Based on the characteristics of dredger fill soil with high water content,high compressibility,and low permeability,this paper proposes a method of vacuum preloading in combination with electroosmosis for the reinforcement of a soft soil foundation.The preliminary investigation was made into the reinforcement mechanism through a laboratory model test.The results show that electroosmosis can effectively accelerate the drainage of the soil foundation when the water content of the soil sample reaches the optimal critical value of 0.85 after the vacuum preloading at the preliminary stage.Obvious vertical and lateral deformation as well as the increase of soil strength near the electrodes can be observed when using this method to treat dredger fill soil.Therefore,for solving the problem that vacuum preloading can only used to effectively reinforce the surface soil with a thickness of about 42.8% of the reinforced depth,the proposed method can be used to reinforce both the surface and deep soils,by vacuum preloading and electroosmosis,respectively,and can thus uniformly reinforce the soil foundation in the depth direction.

As the transition zone of CFRD(concrete faced rock-fill dam),it is especially important to improve the modulus of deformation of supporting layer and transition layer to reduce the board and joint deformations.Because the properties of Hardfill material are between concrete and rockfill,its deformation modulus is relatively high.Thus it is an ideal material to be used as the cushion and transition.Based on the three-dimensional finite element analysis technology,the performances of the CFRD using Hardfill material for the supporting layer and traditional CFRD are comparative analyzed.The results show that using Hardfill material for the supporting layer can effectively ameliorate stress and deformation status and reduce vertical joint and perimeter joint deformation.The maximal tension stresses along the facing slope and along the axis of dam can respectively be reduced by 19.5 percent and 7.9 percent,and the deformation of the vertical joint and the perimeter joint can be reduced by 54.5 percent and 48.9 percent,respectively.This study can afford a good reference for the development of CFRD.

Because of the strong earthquake,the facing of a concrete facing rock-fill dam is prone to crack in a large scale and the large deformation of tension and shear is very easy to happen in its vertical joints and perimeter joints,and as a result,the seepage is easy to happen.Because of the properties of the hardfill material between the concrete and rockfill,the supporting layer of the hardfill material can more effectively diminish the earthquake deformation of the facing.The result of the three-dimensional FEM dynamic analysis indicates that the earthquake response of the facing and the earthquake deformation of the joints can be largely decreased with the hardfill material as the supporting layer of the facing rockfill dam.