| dc.description.abstract | Liquefaction has become a major concern in geotechnical engineering,
particularly after several large earthquakes caused severe damage to
structures in coastal areas of Indonesia dominated by saturated sand
layers. In addition to the loss of soil bearing capacity, liquefaction also
triggers vertical deformation (ground surface subsidence), which
significantly affects simple structures such as low-rise residential
houses. This study aims to estimate ground deformation due to
liquefaction using Standard Penetration Test (N-SPT) data and to
formulate preliminary foundation recommendations based on estimated
vertical deformation zones in the coastal area of Glagah Village,
Kulonprogo. The analysis uses the Seed & Idriss (1982) method to
evaluate liquefaction potential through the factor of safety (FS), and the
Zhang et al. (2002) approach to estimate volumetric strain and vertical
settlement. Liquefaction was assessed at 2-meter depth intervals, with
results indicating potential liquefaction at all boreholes. Under a
magnitude 7.5 scenario, it is predicted at depths of 2–12 meters,
extending to 16 meters at DB-81. For Mw 6.5, it occurs at 2–10 meters,
reaching 12 meters at DB-81. Estimated settlements range from 0.29 to
0.59 meters (Mw 7.5) and 0.17 to 0.42 meters (Mw 6.5), classifying the
area as high risk. As a technical response, deep foundation systems
(mini piles) combined with structural tie beams are recommended to
ensure load transfer and stability. It should be noted that deformation
estimates are limited to subsurface soil response and do not incorporate
building-specific loads or structural dimensions. Nonetheless, this
simple yet field-based approach provides a practical reference for the
development of liquefaction-resistant and inclusive residential areas as
part of the strategic vision for Indonesia Emas 2045. | en_US |
