How can retaining walls be made safe during an earthquake?

3 How can retaining walls be built for earthquake resistance?

Constructing retaining walls for earthquake resistance requires following design specifications, using quality materials, and applying good workmanship. To ensure the wall is earthquake-resistant, it's important to prepare the foundation and backfill carefully. The foundation should be level, compact, and free of organic matter or debris, while the backfill should be well-graded, compacted, and moistened to avoid settlement or voids. Additionally, the wall components should be aligned vertically and horizontally with adequate overlap or interlock between them. They must also be secured to the foundation and reinforcement with appropriate connectors such as bolts, nails, or clips. Regular inspections and tests should be conducted on the wall for cracks, deformations, or displacements during and after construction. Stability and performance can be tested under simulated or actual seismic loads using methods like load tests, vibration tests, or shake table tests.

4 How can retaining walls be maintained for earthquake resistance?

Maintaining retaining walls for earthquake resistance is a critical task, requiring periodic checks and repairs, especially after a seismic event. Visual inspection, surveying, or instrumentation can be used to monitor and measure the wall condition and performance. Signs of damage, such as cracks, bulges, tilts, or gaps should be checked for and changes in height, width, or alignment should be measured. If any damage or deterioration is detected, the wall should be repaired and restored as soon as possible. This may include filling cracks, replacing components, adding reinforcement, or strengthening the foundation. Additionally, if the design or construction standards have changed or the seismic hazard has increased, the wall should be updated and upgraded by modifying the geometry, material, or reinforcement or adding new features such as anchors, braces, or buttresses.

5 What are some examples of earthquake-resistant retaining walls?

Earthquake-resistant retaining walls are found all around the world, some of which have withstood major quakes with minimal or no damage. For example, the reinforced concrete retaining walls along the Los Angeles River in California, built in the 1930s and 1940s, have endured several strong earthquakes, such as the 1971 San Fernando and the 1994 Northridge quakes. Similarly, segmental block retaining walls along the Interstate 5 in Washington, constructed in the 1980s and 1990s, performed well during the 2001 Nisqually quake due to their flexible and interlocking design. Additionally, geosynthetic-reinforced soil retaining walls at the Port of Kobe in Japan, erected in the 2000s, resisted the 2011 Tohoku quake due to their high strength and ductility.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?