Case study of a foundation failure induced by cyclic softening of clay during the 2023 Kahramanmaraş earthquakes

Abstract

The Kahramanmaraş Earthquakes that occurred on 6 February 2023 resulted in extensive structural failures, including damages caused by soil liquefaction. This study focused on investigating the excessive settlements observed in buildings along Ataturk Boulevard in the Golbasi district, with a primary emphasis on the toppling failure of the Kayı Apartment. Field exploration, laboratory testing, and bearing capacity analyses were conducted to understand the failure mechanism. Since the foundation soil of Kayı Apartment predominantly consisted of clay, soil liquefaction alone could not explain the observed failure. Instead, the cyclic softening of clayey soil underground shaking was identified as a significant factor contributing to the damage. As one of the rare case histories documenting a failure caused by cyclic softening, the results of the study also shed light on the excessive displacements observed in nearby buildings with fewer stories that managed to withstand the earthquake without experiencing complete bearing capacity failure.