Study On The Interaction Of Cut-off Wall And Earth-rock Dam Based On Coupling Of Seepage And Stress

The closed cut-off wall was widely used in the reinforcement projects ofearth-rock dam. As the influences of consolidation and the load-type were different,the bearing characteristics of closed cut-off wall and the interaction law between thedam and wall were quite different compared with the wall in the cofferdam or in thedeep covering layer. At present, researches on the stress-strain of the wall and itsinfluences on slope stability were very few when building closed cut-off wall in thereinforcement works of earth-rock dam. Beyond this, seepage-stress coupling wasrarely considered in the research on the interaction between the dam and wall.However, seepage-stress coupling definitely existed in the earth-rock dam. Theseepage-stress coupling should be considered in the study with the furtherdevelopment of the study on interaction between the dam and wall.According the above problems, the closed cut-off wall built in the reinforcementproject of earth-rock dam was selected as the study object in this paper. Bycomprehensively analyzing the project conditions of building cut-off wall in theearth-rock dam, the numerical model was established. The contacts of wall-damtogether with the coupling of seepage-stress were taken into account in the model.Based on the systematic study of the interaction between the wall and dam, thebearing characteristics, applicability of the cut-off wall and its influences on slopestability were discussed. The research achievements of this paper can be useful inbuilding a scientific, safety and economical cut-off wall. The main achievements andresults are as follows.For the situation of building closed cut-off wall in the earth-rock dam, thenumerical simulation method of modeling the interaction of the wall and dam wasproposed. The wall-dam coupling and seepage-stress coupling were considered in themodel, and the results of the numerical modeling were verified by a typical theoreticalformula calculation. According to the comparative analysis, the wall stress wasobviously smaller when the seepage-stress coupling effect was ignored.Basing on the calculation of seepage-stress coupling, the mechanisms and therules of the interaction between the cut-off wall and the dam were systematicallyresearched, the bearing characteristics and availability of the closed cut-off wall underdifferent conditions was also analyzed. In the condition of normal storage level, theclosed cut-off wall was mainly bearing the horizontal stress which was caused by thehydraulic head of upstream and downstream. The rigid concrete cut-off wall was mainly bearing tensile stress, while the plastic concrete cut-off wall bearing completepressure stress. The stress of the rigid concrete cut-off wall was obviously influencedby the dam material, seepage characteristics and strength of bed rock while the stressof the plastic wall was rarely influenced.According to the changes of the stress field and the seepage field when buildinga cut-off wall, the affect of the cut-off wall on the slope stability was systematicallyresearched. The stability safety factor of downstream slope increased while theupstream slope decreased after building a cut-off wall.