Project Description

The K-12 educational project –Phase 1- involved the preparation of 1 million square feet of area in the Coachella Valley for the construction of a new school complex. The site, located at 8 miles distance from the San Andrea fault, was designed for a magnitude Mw = 7.5 and horizontal acceleration of ah = 0.5 g.

Seismic mitigation of fine and silty sands is necessary to prevent uncontrolled subsidence of the ground surface during earthquakes. Triggering of liquefaction induced phenomena no longer occurs once the void ratio has been reduced below a certain range, determined based on the characteristics of the designed earthquake.

So for this site the Dynamic Compaction technique was used in order to prevent liquefaction of the soil in the case of an earthquake.

The compaction of the upper 40 feet of soil necessitated an energy of 27 tons dropped from a height of 100 feet.

Acceptance testing used dual Standard Penetration Testing and Static Cone Testing procedures.