Stability Analysis of Micro Pile Reinforced Idukki Soil Slopes-PPT Presentation

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The study evaluates slope stability in Idukki district, Kerala, where rainfall frequently triggers landslides and slope failures. Using MIDAS GTS NX finite-element software and the Strength Reduction Method, the researchers modelled ten existing slopes with the Mohr–Coulomb soil model. Stability was assessed under dry and saturated conditions, with saturation represented by setting the ground surface as the piezometric level.<br /><br />Rainfall substantially reduced the factor of safety (FOS). Four slopes—at St. Marie’s Chapel, Munnar Government Arts College, Velliyamattam Panchayath, and Kallar—were unstable in both conditions. The Aadit slope was stable when dry but unstable when saturated. The other five slopes remained stable in both cases.<br /><br />The four critical slopes were then analysed with different micropile layouts. Micropiles were modelled as linear-elastic elements, with a concrete cap beam anchoring the pile array. The best tested arrangements raised FOS from 0.99 to 1.59 at St. Marie’s Chapel, 1.28 to 1.64 at Aadit, 0.82 to 1.29 at Kallar, and 0.62 to 1.23 at Velliyamattam. Thus, reinforcement improved stability, although the 1.5 target FOS was not achieved at every site.<br /><br />The analysis indicates that battered piles generally perform better than vertical piles alone. Longer piles extending beyond the failure surface, closer spacing, and placement between the slope toe and middle also improve stability. However, achieving adequate fixity in very weak slopes may require impractically long piles and tight spacing. The study identifies micropiles as a useful stabilization option, particularly for steep, highly unstable slopes.

Keywords

slope stability

Idukki district

rainfall-induced landslides

factor of safety

MIDAS GTS NX

Strength Reduction Method

Mohr-Coulomb model

micropiles

battered piles

Kerala slopes