Combination of rockfill dam reinforced concrete face and seepage control wall in the foundation: stress-strain state

Hydraulic engineering

Introduction. Construction of reinforced concrete face rockfill dams on soil foundations requires solving the problem of arranging a safe diagram of conjugation between a dam reinforced concrete face and a seepage control structure in the foundation. The object of research is the Miaojiaba dam, 111 m high (Gansu, China), which in the channel part rests on a huge layer of soil base, and in the side sections is located on rocks. Materials and Methods. Stress-strain state (SSS) of a reinforced concrete face (CF) and a cutoff wall (COW) of the considered dam was studied with the aid of numerical modeling. The study was conducted in 2D and 3D formulations. Finite elements with high degree of approximation inside the elements are to be used for modeling of thin-wall structures. Results. By the results of numerical modeling the CF and COW are subject to complicated deformations and are in a complicated stress state. It is characterized by presence of considerable compressive forces both in the face and in the wall. Nevertheless, compressive forces do not exceed the limit compressive strength of concrete. Tensile stresses are more dangerous for strength of seepage control structures. In the face the tensile stresses appear in the zone of conjugation with rock foundation. COW is subject to tension in the zone of rest on a stiff concrete apron. Besides, COW separates from rock sides. All this creates the danger of failure of seepage control protection tightness. Conclusions. At designing rockfill dams with combination of a reinforced concrete face and a seepage control wall a special attention should be paid to spatial conditions of these elements’ performance. This will help in finding the zone of appearance of dangerous stresses, which are not seen at solving a 2D problem. However, it is evident that conjugation of CF with COW with the aid of a stiff concrete apron is not a safe solution.