Case Study Of Geogrid Reinforcements In Maligcong Rice Terraces: A Proposed Restoration For A Cultural Heritage

Abstract

The Geogrid reinforcement case study on Maligcong Rice Terraces substantiates the feasibility of the proposed restoration. Soil exploration and slope stability analysis played pivotal roles in strengthening these justifications. The Swedish Weight Sounding Test identified loose and medium layers, albeit with constrained detailed information on loose layers. Penetration resistance trends indicated a direct proportionality to depth, reflecting prevalent sands. Subsurface layer examinations revealed uniform saturated soils with poorly graded sands and consistently inferior well-graded sands. Poorly-graded sands increased in medium layers, and rice paddy moisture content showed significant variability across surface layers. In slope stability analysis, Bishop's method supplemented Janbu's, yielding a conservative deterministic factor of safety. The bare slope appeared marginally stable deterministically but stable probabilistically. Introducing a water table shifted the scenario to instability, identified as the worst-case. Incorporating geogrid reinforcements under the worst-case scenario resulted in a marginally stable deterministic factor and a stable probabilistic factor. A 1-meter vertical spacing achieved stable factors in the worst-case, yet failed external stability requirements by the AASHTO-ASD method. AASHTO-ASD method-derived vertical spacing could be desirable probabilistically. Construction faced challenges, necessitating manual labor due to the infeasibility of machinery unfeasibility. Productivity rates remained practical, with divergence between traditional and proposed restoration in geogrid embedment length. Challenges included labor availability, upper paddy erosion, water-related issues, and achieving proper compaction, addressed by strategic methods. Cost-Benefit Analysis hinged on total cost and serviceability, with the proposed restoration surpassing the traditional method's Cost-Benefit Ratio, justifying its adoption.