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Liquefaction Susceptibility Plot of Gerona, Central Luzon Philippines

Edwin L. Dela Vega
College of Engineering, Tarlac State University, Tarlac City, Philippines

Abstract—The 1990 earthquake in the Central Luzon, Philippines manifested sand boils and land deformations in Gerona, Tarlac signifying the town’s susceptibility to soil liquefaction. Liquefaction-susceptible sediments are water-saturated, loose, fine-grained sand deposits. Ocular inspection was done to survey and select the sites to be considered. Standard penetration test (SPT) was employed to establish the geotechnical profile, subsurface conditions, and the soil bearing pressure of the underlying soil formation. Seven boreholes were drilled in selected areas namely Tagumbao (BH1), Danzo (BH2), Apsayan (BH3), Poblacion (BH4), Matayungcab (BH5), Salapungan (BH6), and San Antonio (BH7). The method of Seed and Idriss was applied to compute for the liquefaction potential index (LPI) of selected sites in Gerona. MathCAD was used to generate the liquefaction susceptibility plots at varying earthquake magnitudes. At earthquake of magnitude 5.0, the area within the vicinity of BH 7 has low liquefaction potential. At earthquake of magnitude 6.0, all areas within the vicinity of the SPT sites will liquefy except on areas near BH 3 and at earthquake of magnitude 7.5, the entire area within the vicinity of the SPT sites is highly liquefiable.
Index Terms—liquefaction, susceptibility, mapping, SPT, USCS, LPI

Cite: Edwin L. Dela Vega, "Liquefaction Susceptibility Plot of Gerona, Central Luzon Philippines," International Journal of Structural and Civil Engineering Research, Vol. 5, No. 4, pp. 292-295, November 2016. doi: 10.18178/ijscer.5.4.292-295