Patent ID: 7011475

Claim:
A method for preventing seismic liquefaction of ground in a built-up urban area where a loose fine-grained layer vulnerable to seismic liquefaction is underlain with a soft cohesive layer liable to uneven settlement caused by lowering of a groundwater table, with a deep granular layer underlying said soft cohesive layer, said method comprising the steps of: pumping pore water out of said loose fine-grained layer to lower the groundwater table and thereby create pore voids in said loose fine-grained layer; pressurizing and pushing said pumped pore water down through said soft cohesive layer into said deep granular layer, an uplift force of said pumped pore water counteracting a downward force caused by the lowering of the groundwater table in said loose fine-grained layer; blending tap water saturated with dissolved air, micro particles of mineral powder and a diffusing agent in a regulating tube as a tap water mixture; injecting said tap water mixture into said pore voids in said loose fine-grained layer until said pore voids are filled; and forming, following completion of the foregoing step of injecting said tap water mixture, an air-mixed zone in which a plurality of air bubbles make cores of the micro particles of said mineral powder and are thereby bubbled out of said mixture such that a degree of pore water saturation in said loose fine-grained layer is reduced to prevent seismic liquefaction due to earthquake.