<p>This study investigates the effects of Geosynthetic Clay Liner (GCL) installation methods on the seismic stability and deformation behavior of small earth-fill dams through dynamic centrifuge model tests. A comparison of two GCL installation cases was conducted to evaluate deformation behavior and the applicability of stability calculation methods. The results revealed that an increase in the average slope angle of the GCL installed in the staircase configuration (i.e., the GCL installation angle) led to greater settlement at the upstream crest and deformation of embankment. Additionally, increasing the angle alters the failure mode from translational sliding along the GCL boundary to slope deformation independent of the GCL boundary. Furthermore, the installation angle significantly affects the suitability of stability calculation methods; for steeper slopes, conventional translational sliding analyses may not be applicable. These findings provide critical insights into optimizing GCL utilization in earth-fill dam design and underscore the importance of selecting appropriate stability evaluation approaches. Through numerical analysis, future research should focus on delineating the boundaries of failure mode transitions, elucidating underlying mechanical mechanisms, and developing generalized stability calculation methods that are independent of the installation angle of the GCL.</p>