Diaphragm walls are commonly employed as a permanent support for the building of metro stations near urban valley, and in conjunction with the interior sidewalls of the station structure to withstand the pressure from surrounding soils. Despite their prevalent use, the effect of underground diaphragm walls on the seismic response of stations is not yet fully understood. In this paper, a series of 1-g shaking table tests is designed to investigate the seismic response of a near-valley station with underground diaphragm walls within the elastic range. Modeling the stratum-structure-diaphragm walls system is accomplished by employing granular concrete reinforced with galvanized steel wires and synthetic model soils, and a station without diaphragm walls is included, serving as a benchmark for comparative analysis to understand the influence of diaphragm walls on the seismic behavior of the station. The experiment was designed for three depth-to-width ratios (DWRs), i.e. 1/3, 1/4, and 1/8, of arc-shaped valley topography, as well as the seismic excitations for the test include actual seismic records with the amplitude of 0.2 g, 0.4 g, and 0.8 g, respectively. Results show that the underground diaphragm walls enhance the lateral stiffness of the near-valley station compared to structures without diaphragm walls, and thus significantly reducing the racking deformation of structure during earthquakes. The presence of diaphragm wall would decrease the amplification of dynamic earth pressure caused by valley effect at the structural sidewalls, and significantly reduce the lateral vibration and shear effect of the station near a valley with a larger DWR. Notably, bending moment response at the connection between the diaphragm walls and structural sidewalls are dramatically amplified under strong seismic loading, and such adverse effects gradually increase with the DWR of the valley.

On February 6th, 2023, southeastern T & uuml;rkiye was shaken by two catastrophic earthquakes, close to northwestern Syrian border. The first earthquake (Pazarc & imath;k) occurred 45 km west of Gaziantep at 1:17:32 (UTC), with a shallow strike-slip faulting at a depth of approximately 8.6 km and a moment magnitude (MW) of around 7.7. The second event (Elbistan) took place 9 h later, 66 km north-east of Kahramanmaras, city center, also with shallow strike-slip faulting at a depth approximately 7 km and an MW of around 7.6. Turkish authorities reported a death toll of over 59,000 in T & uuml;rkiye and about 8500 in Syria. The destructive effect of the earthquake resulted from widespread strong ground shaking, a rupture length exceeding 300 km, causing collapse of a large number of buildings. The catastrophic destruction of the built environment was accompanied by a range of other earthquake-related effects, including fault ruptures, landslides, and soil liquefaction. The aim of the study is to analyze the distribution of ground motion and their relationships with the observed damages for the two events. Spectral accelerations of key importance were assessed across a large area in the southeastern part of T & uuml;rkiye. Notably, these accelerations were generally much higher than existing design spectra. A significant correlation between the observed concentration of damage and the significant amplification of motion induced by local soil conditions (such as soft soils and valley effects). The distinct tectonic structure of the region could be the main reason for the high amplification in the valleys (associated with basin effects), even at large distances from the epicenter, especially in correspondence with the bidimensional grabentype geological structures. The investigation delved into the analysis of four specific regions in detail: Antakya and Hassa (both in the Hatay province), Kahramanmaras, and Goksun. Notably, the observable valley effects were found to play a significant role and could account for the significant damage observed in these regions.