Seismic Performance of Drained Piles in Layered Soils

Area of Science:

• Geotechnical Engineering
• Earthquake Engineering

Background:

• Strong ground motion can induce excess pore pressure, leading to soil liquefaction, reduced stiffness, and strength loss.
• Geotechnical elements like piles are crucial for ground improvement, but their performance under seismic loads needs enhancement.

Purpose of the Study:

• To investigate the effectiveness of drained piles in reducing liquefaction hazards during seismic events.
• To evaluate the impact of drain configuration and discharge capacity on excess pore pressure and ground motion de-amplification.

Main Methods:

• Conducted a series of shaking table tests using layered soil models with single and grouped drained piles.
• Varied the number and orientation of drains per pile to assess their influence on porewater discharge and excess pore pressure.
• Monitored acceleration time histories and porewater discharge to analyze the de-amplification of ground motion.

Main Results:

• Drained piles demonstrated superior performance over conventional piles in managing excess pore pressure and maintaining soil stiffness.
• Improved performance correlated directly with increased discharge capacity of the drained piles.
• Observed a direct relationship between porewater discharge rate, excess pore pressure generation, and ground motion de-amplification.

Conclusions:

• Drained piles significantly reduce seismic-induced excess pore pressure and enhance soil stability.
• The number of drains per pile and their discharge capacity are critical factors for effective liquefaction hazard mitigation.
• This technology offers a promising solution for improving the seismic resilience of slopes with low-permeability soils.