Determination of dynamic properties of pumice containing soils in Isparta

This study experimentally investigates the dynamic behavior of pumice soils, which are commonly found in the Isparta province, under both drained and undrained conditions. Due to its porous and brittle structure, pumice is a soil type with low bearing capacity and is particularly sensitive to seismic effects. It is widely distributed throughout the Isparta region. The depth of the groundwater table in the area necessitated the evaluation of both drained and undrained responses. Initially, field investigations conducted in the Çünür, Deregümü, and Işıkkent districts of Isparta were obtained from the Isparta Municipality. These investigations included seismic refraction, multichannel analysis of surface waves (MASW), standard penetration tests (SPT), and geological borings to develop detailed soil profiles. Based on the data collected, the pumice soils were classified in terms of stratigraphic properties, stiffness–density characteristics, and shear wave velocities. The majority of the soils in the study area were found to fall into the ZD soil category. Following the fieldwork, the index properties of the collected samples—such as grain size distribution, water content, and specific gravity—were determined in the laboratory. The samples were prepared at target relative densities using the wet pluviation method and subsequently saturated. Dynamic simple shear tests (DSS-C) with confining pressure were then performed on the saturated specimens. The dynamic tests were conducted under both drained and undrained conditions. All tests were carried out at a vertical effective stress of 100 kPa and dynamic stress ratios of 0.2, 0.25, and 0.3. In the undrained tests, the development of excess pore water pressure and liquefaction behavior were examined, whereas volumetric deformations were analyzed in the drained tests. At the conclusion of the study, deformation behavior, shear modulus, and strain responses of the samples from different districts were compared under both drained and undrained conditions. The findings revealed that pumice-containing soils can undergo significant deformation under dynamic loading and exhibit a potential for liquefaction, particularly under undrained conditions. In drained conditions, the soils showed more stable behavior but were prone to volumetric deformation.