Abstract: A conglomerate layer is formed horizontally on a base of ground which has a high water permeability and easily liquefies. A bottom plate is formed on the conglomerate layer to construct the underground structure thereon. One or more drainpipes are extended upwardly from the conglomerate layer through the bottom plate for draining excessive pore water in the ground.

Abstract: A conglomerate layer is formed in ground which has a high water permeability and is liable to be liquefied. An underground base of the structure is constructed on the conglomerate layer. One or more drainpipes are extended substantially horizontally from the conglomerate layer through the underground base so as to communicate with the surface of the ground.

Abstract: A seismic isolator for absorbing earthquake vibrations is provided which comprises a laminated member arranged to be interposed between a structure and a foundation, the laminated member comprising thin steel sheets having concavities and convexities extending in a single direction, flexible sheets stacked alternately with the steel sheets, and upper and lower end plates, all these sheets and plates being unitarily and fixedly bonded together. The upper and lower end plates are fixed to the structure and the foundation, respectively, in such a manner that the concavities and convexities extend in a direction in which earthquake vibrations are to be isolated from the structure. The seismic isolator of the present invention is particularly suitable for use with a bridge.