Search Results (3)

This study addresses the vital issue of the variability associated with modeling decisions in dam seismic analysis. Traditionally, structural modeling and simulations employ a progressive approach, where more complex models are gradually incorporated. For example, if previous levels indicate insufficient seismic safety margins, a more advanced analysis is then undertaken. Recognizing the constraints and evaluating the influence of various methods is essential for improving the comprehension and effectiveness of dam safety assessments. To this end, an extensive parametric study is carried out to evaluate the seismic response variability of the Koyna and Pine Flat dams using various solution approaches and model complexities. Numerical simulations are conducted in a 2D framework across three software programs, encompassing different dam system configurations. Additional complexity is introduced by simulating reservoir dynamics with Westergaard-added mass or acoustic elements. Linear and nonlinear analyses are performed, incorporating pertinent material properties, employing the concrete damage plasticity model in the latter. Modal parameters and crest displacement time histories are used to highlight variability among the selected solution procedures and model complexities. Finally, recommendations are made regarding the adequacy and robustness of each method, specifying the scenarios in which they are most effectively applied. Full article

Due to the construction technology of roller compacted concrete (RCC) gravity dams, there are many weak layers that have the potential to affect the seismic performance of dams. However, research on the seismic response and failure characteristics of RCC dams considering their layered characteristic is still lacking. In this paper, the zero-thickness cohesive element is presented to model the mechanical behavior of the RCC layers. An impacted concrete beam is selected to verify its effects on simulating crack propagation. Subsequently, the concrete damaged plasticity model is utilized to model concrete under seismic loading. The dynamic interaction in the gravity dam-reservoir-foundation system is considered by coupled acoustic-structural method, whose rationality is validated by seismic failure mode analysis of the Koyna dam under the 1967 Koyna earthquake. The validated algorithms are applied to investigate the influence of the weak layer at different elevations on the seismic response and the failure process of the Guandi RCC gravity dam. On this basis, the effects of well-bonded RCC layers set at intervals along the dam on the nonlinear response and failure modes under strong earthquakes are further investigated. The results reveal that the weak layer will influence the anti-seismic capacity of RCC gravity dams, and the damage characteristics of the dam are significantly changed. In addition, well-bonded RCC layers still affect the seismic response of RCC gravity dams. Increasing displacement response and energy dissipation can be observed. Meanwhile, RCC layers lead to more severe damage to the dam under the same seismic input. Full article

The Koyna-Warna area in Maharashtra, Western India, is one of the world’s best examples of reservoir-induced seismicity. The occurrence of earthquakes in the vicinity of Koyna Dam (Shivaji Sagar Lake) started since 1962, soon after the initiation of water impoundment. To understand the tectonics and seismicity of the region, recent Landsat 8 images and Sentinel radar data were evaluated in GIS, as well as SRTM and ASTER Digital Elevation Model data (DEM) and the DEM-derived morphometric maps. Geophysical and climate data were also included in the GIS database. The analysis of satellite data contributed towards understanding the tectonic framework of the Koyna reservoir area by visual lineament analysis. Thus, Landsat 8 and Sentinel radar data brought out the structural pattern and made visible larger fault zones. The detailed lineament analysis detected areas, presumed to have rocks of relatively higher permeability, supporting intrusion and infiltration of surface water. The resulting maps of weighted overlay procedures derived from causal morphometric factors that influence the susceptibility to ground motion revealed areas with higher, medium and lower susceptibility to soil amplification. Full article