Performance of Reyhanlı Dam during February 6, 2023 Kahramanmaras,-Türkiye earthquake sequence

Abstract

The February 6, 2023 T & uuml;rkiye-Kahramanmaras, earthquake sequence subjected Reyhanl & imath; Dam to strong nearsource ground motions. The dam is located in Hatay-Reyhanl & imath; district of T & uuml;rkiye, 23.2 km away from the fault rupture plane of the Kahramanmaras,-Pazarc & imath;k M7.8 event. The peak ground acceleration at comparable distances from the fault ruptures was estimated to vary in the range 0.1-0.4 g and 0.02-0.04 g, during Pazarc & imath;k and Ekinoz & uuml;-Elbistan events. Consistently the peak ground rock acceleration at the dam site is governed by Pazarc & imath;k event, and estimated as 0.3 g. The permanent total ground deformations, in terms of lateral and vertical displacements were mapped at the crest and reported to vary in the range of 10-30 cm, and 100-120 cm, respectively. No surface manifestation of soil liquefaction was observed at the dam body, or at its foundation soils. As part of preliminary reconnaissance assessments, limit equilibrium-based slope stability and simplified permanent deformation assessments were performed to evaluate the conformity of the predicted and observed responses. In between KM: 0+900 to 2+000 the permanent displacements consistently increase with increasing the transverse section height of the dam. Bray and Travasarou (2007) [20] semi-empirical simplified method produced the most consistent predictions for both the upstream and downstream slopes. In between KM: 6+000-8+120, large displacements were observed, higher than the values predicted by all methods, but in better conformance with the ones of Makdisi and Seed (1979) [15]. The increased permanent displacements were attributed to the presence of sand lenses in the foundation, which might have been cyclically softened, or even cyclically liquefied during the Pazarc & imath;k event.