Slope Support and Stabilization Using Existing, Abandoned Timber Piles-PPT Presentation

PPT Presentation

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An industrial site along the Providence River needed to be raised 12–15 feet to protect it from flooding. Test borings and geophysical surveys revealed a deep deposit of organic silt, with especially deep deposits at the eastern end. The proposed fill created unacceptable slope-stability risks and significant consolidation settlement; surcharging was not practical. Existing foundations, supported by dense groups of timber piles, also obstructed installation of new piles.<br /><br />The value-engineered solution treated the existing timber piles as ground improvement to increase slope stability and limit settlement, adding auger-cast piles where needed. A field investigation exposed and cored the timber piles: most were in excellent condition, fewer than 10% showed limited rot, and only a few were severely deteriorated.<br /><br />Static stability was assessed in PLAXIS, modeling individual piles and using strength-reduction analysis to determine the factor of safety. Pile bending moments were also reviewed. For dynamic stability, the pile-reinforced zone’s equivalent strength was back-calculated and analyzed using Slope/W for pseudo-static conditions.<br /><br />The final design incorporated the existing piles, supplemental piles where required, wire-basket slope reinforcement, and riprap wave protection at the slope face.

Keywords

industrial site

Providence River

flood protection

organic silt

slope stability

consolidation settlement

timber piles

ground improvement

PLAXIS analysis

riprap protection