Contact Scouring And Stability Analysis For Earth Rock-fill Dam And Concrete Culvert During Stable Seepage Period

The earth-rockfill dam has been widely used in our country’s existing water conservancy projects for reason of low cost, simple structure, wide range of applications and so on. The concrete culverts which buried in earth-rockfill dams is a kind of important water hydraulic structures, it needs to withstand the seepage-stress coupling, uneven subsidence of soil and the action of gravity and so on. The contact places between soil and the concrete culvert are prone to occur contact scouring, thus causing excessive seepage will lead to the seepage failure.This paper have introduced the basic theory of seepage analysis and established several three-dimensional finite element analysis models which include concrete culverts in steady seepage period. The finite element analysis models of earth-rockfill dam use the Mohr-Coulomb constitutive model for calculating seepage-stress coupling process, the element analysis models in seepage effect and seepage-stress coupling effect are established respectively for different working conditions.Based on the the study of contact scouring between soil and the concrete culvert we can drew the following conclusions:The pore pressure at the observation points decrease as the water head height decrease. There is maximum rate of change of pore pressure in the the front and rear end of the earth-rockfill dam; the pore pressure remains stable in the middle of the earth-rockfill dam. In general, the velocity at the place which between soil and the concrete culvert decreases as the water head height decreases.Generally, the velocity and pore pressure in the seepage process are greater than in the the seepage-stress coupling process. The results which use the Mohr-Coulomb constitutive model show that the stress has a great influence on the pore pressure and flow rate, it makes the contact scouring and adverse conditions more likely to happen. So the seepage-stress coupling should be considered in our study.There is little difference between if there are seepage cutoff collars or not in the seepage velocity variation, both of them have the same seepage velocity variation which has a higher seepage velocity in a higher water head height. The earth-rockfill dams which contain the seepage cutoff collars have lower seepage velocity than the earth-rockfill dams whcih have no seepage cutoff collar, so the seepage cutoff collars play an effective role in controlling the seepage in the earth-rockfill dams.