Stability Analysis of Micro Pile Reinforced Idukki Soil Slopes-Paper

Paper

Pdf Summary

The study evaluates whether micropiles can improve the stability of rainfall-prone soil slopes in Kerala’s Idukki district. Ten slopes were modelled in MIDAS GTS NX using three-dimensional finite-element analysis and the shear strength reduction method. Soil was represented by the Mohr–Coulomb model. Dry conditions were compared with a fully saturated scenario, simulated by setting the piezometric surface at ground level.<br /><br />Saturation substantially reduced the factor of safety (FOS). Four slopes had FOS values below 1 when saturated: St. Maries Chapel (0.99), Munnar Government Arts College (0.34), Velliyamattam Panchayath (0.62), and Kallar landslide (0.82). Four unsafe slopes—St. Maries, Aadit, Kallar, and Velliyamattam—were then assessed with different micropile configurations.<br /><br />Micropiles improved FOS and reduced slope displacement in all four cases. The best configurations raised FOS from 0.99 to 1.59 at St. Maries, 1.28 to 1.64 at Aadit, 0.82 to 1.29 at Kallar, and 0.62 to 1.23 at Velliyamattam. The results indicate that pile position and geometry should be tailored to the failure surface. Battered piles generally performed better than vertical piles, while placement between the toe and middle of the slope was effective for some sites. Deep-seated failures required longer, more closely spaced piles extending beyond the slip surface.<br /><br />Although reinforcement improved every analysed slope, the target FOS of 1.5 was not reached for Kallar or Velliyamattam, and the required deep, dense pile systems may be difficult to install. Overall, the analysis supports micropiles as a potentially effective slope-stabilization measure, while highlighting the importance of site-specific design and practical installation constraints.

Keywords

micropiles

slope stability

factor of safety

finite element analysis

shear strength reduction

rainfall-induced landslides

Kerala

Idukki district

soil slope reinforcement

Mohr-Coulomb model