Composite particles of a hard core coated by a layer of hydratable, swellable clay such as bentonite are useful for constructing, modifying and/or supporting lifeline structure such as dams, berms and levees, and/or pipelines or conduits for oil, gas, sewage, water, or cables or wires for transmission of electrical power or data information. The method involves placing the composite particles in a location within, below, or about the lifeline structure, and hydrating them to cause them to swell and fill and seal the voids around the structure to form a resilient support having a high damping ratio and low hydraulic conductivity that is maintained after exposure to strain forces. The composite particles are advantageous in damping seismic waves and reducing the potential damage from an earthquake, explosion, tremor, fatigue loading, or similar seismic event.