Design of the Timber Pile Ground Improvement for Liquefaction Mitigations 

 Project Lead: Armin Stuedlein

Project duration: 7/1/17 – 6/30/19

 

Liquefaction caused damage to 25,000 homes in the 2011 Tohoku earthquake in Japan and $15 billion in losses in Christchurch in 2010-11. This project will propose design guidelines for the use of timber piles, a timber product widely-used for structural support of buildings, to mitigate against liquefaction hazards. This approach has application in protecting a broad range of other structures, including port and harbor facilities, bridge approach embankments, and bridge foundations. While significant field-based experimental research has been conducted by the PIs to-date, there does not exist a set of design guidelines to handle both the densification and reinforcement effect. The results of this research will be used by engineers who need to follow specific design guidelines to ensure that an appropriate liquefaction mitigation design can be provided.

 

Objectives

This project seeks to formalize design procedures for engineers that wish to use the economical driven timber pile ground improvement alternative for the mitigation of earthquake-induced liquefaction, but have dismissed this alternative owing to the lack of availability of such procedures. Specifically, the objectives are to:

  • Develop and validate sophisticated numerical models that have been calibrated to the data from the aforementioned tests;

  • Use the calibrated numerical model to perform nonlinear effective stress site response analyses and deformation analyses of typical ground improvement arrangements and acceleration time histories;

  • Determine what steps are necessary to replicate the sophisticated numerical analyses using common 2D slope stability analyses (e.g., 3D to 2D conversion of soil and reinforcement properties, selection of horizontal acceleration coefficients, etc.);

  • Conduct parametric analyses to determine which parameters are most critical for optimization of ground improvement methodologies; and,

  • Condense the work in (1) through (4) to formalize specific design guidelines and communicate findings to industry.