Design of landslide stabilizing piles by numerical techniques and several other methods-PPT Presentation

PPT Presentation

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The presentation describes the design and performance of a pile-supported stabilization system for the Estrondo landslide in Encino, California. The site was a steep, 110-foot-high fill slope over diatomaceous bedrock that had failed repeatedly. A major failure in 1998 prompted extensive investigation, and the design team was engaged in 2002 to develop a repair.<br /><br />The stabilization work included a toe protection wall, mid-slope drilled shafts and wall, tieback anchors, a drainage curtain/gallery, excavation and wall construction, and a second row of tiebacks. Slope inclinometers and other instrumentation were used to monitor performance, including during the heavy 2005 El Niño rains.<br /><br />The presentation compares three broad design approaches: limit-equilibrium methods, plasticity-based methods, and numerical finite-element or finite-difference modeling. It discusses the traditional unbalanced-force method, which is familiar to agencies and has a record of successful performance but may duplicate safety factors and produce inconsistent or uneconomical designs.<br /><br />The main focus is the Strength Reduction Method (SRM) in numerical modeling. In SRM, soil strengths are progressively reduced until instability occurs. Models can reveal the critical failure mechanism without assuming it in advance, and can assess slope deformation, pile bending moments, tieback loads, and the effects of changing pile location or capacity. The presenter notes that complex models can have convergence issues and require experienced users and reviewers.<br /><br />The presentation concludes that numerical modeling is a versatile design tool for complex slope stabilizations. Used alongside limit-equilibrium analysis, it can reduce uncertainty, support sensitivity studies, and provide predictions that can be compared with construction monitoring.

Keywords

landslide stabilization

pile-supported system

Encino California

Estrondo landslide

drilled shafts

tieback anchors

drainage gallery

strength reduction method

finite element modeling

slope monitoring