Seismic response of concrete-rockfill combination dam using large-scale shaking table tests

Concrete-rockfill combination dam (CRCD), a new type of dam, is mainly composed of an upstream concrete wall and a downstream inclined rockfill body. It is not in direct contact with the bedrock foundation but a water stop, which is different from conventional concrete gravity dam. The dynamic characteristics of CRCD are not quite fully understood yet. In this paper, large-scale models of CRCD were constructed and key parameters, such as acceleration-time response, dynamic earth pressure, deformation and failure pattern of slope were monitored. Results showed that the amplification factors in the upper part (0.6 H) increased with the height. The model dam showed obvious concentration and amplification effect on the low frequency component. The total earth pressure acting on the back face of the wall varied approximately nonlinear along the wall height when the PGA exceeded 0.4g. In addition, the CRCD model exhibited good seismic performance with small residual deformation under earthquake. A shallow sliding mode of failure at a height of 0.8 H was measured from the base on the downstream slope. Therefore, it was prudent to undertake some aseismatic reinforcement measurements at the top 1/5 thickness zone of the slope. These model test results could provide a certain reference value for preliminary understanding and qualitative analysis of a prototype CRCD.