Earthquake drains are installed in loose, sandy soils that may liquefy during an earthquake to reduce the risk of liquefaction and excessive damage to structures.
- Mitigate liquefaction
Earthquake drains are installed by vibrating the insertion mandrel during penetration and removal. Typically, the insertion mandrel consists of a heavy-gauge steel pipe with three equally spaced fins to transfer vibrations to the adjacent soil. The vibrations result in some densification of the granular soils, assisting in the liquefaction mitigation.
Earthquake drains consist of high flow capacity, prefabricated vertical drains with about 75mm diameters. The core is tightly wrapped with geotextile filter fabric (selected for its filtration properties), allowing free access of pore water into the drain, while preventing the piping of fines from adjacent soils. The geotextile wrap is very durable and able to withstand the handling and abrasion that occurs during installation. Several core designs and fabric types can be used to fit a variety of drainage applications and soil classifications.
Liquefaction mitigation achieved with Earthquake Drains can be valuable for support of embankments, reduction of lateral spreading from seismic loading, containment of densified ground, support of floor slabs in certain conditions, liquefaction mitigation of mine tailings, and reducing seismic deformations of pile groups. Combined with other ground improvement techniques, earthquake drains can be applied to big box stores, nominal loading conditions, mid-rise buildings, tanks, ports, and hydraulic fills.