Patent ID: 7192221

Claim:
A system 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 system comprising: a plurality of vertically-extending wells, with pumps submerged therein, at spaced intervals along each side of a street, each of said wells including a top well extending through the loose fine-grained layer, and a bottom well extending down into said deep granular layer; a main water pipe and a reverse flow main pipe placed along each side of said street and running generally horizontally, said pipes in communication with said wells; an air-tight tank with an associated air compressor coupled to said pipes; said submerged pumps configured to pump pore water out of said loose fine-grained layer into said air-tight tank to lower the groundwater table from an initial groundwater level to a bottom level of said loose fine-grained layer and to thereby create pore voids in said loose fine-grained layer; said air-tight tank configured to pressurize said pore water using said air compressor and to push pressurized pore water through said reverse-flow main pipe into said deep granular layer while reciprocally injecting compressed air into said deep granular layer to remove clogging, an uplift force of said compressed air and said pumped pore water counteracting a downward force caused by the lowering of the groundwater table in said loose fine-grained layer; a regulating receptacle configured to blend tap water overly saturated with dissolved air, micro particles of mineral powder including silica and a does diffusing agent sufficient to prevent aggregation into a tap water mixture, said regulating receptacle also being configured to be coupled to said pipes after said groundwater table has been lowered to said bottom level of said loose fine-grained layer; and a supply water valve configured in an open position thereof to pass said tap water mixture injected therein from said regulating receptacle into said pore voids in said loose fine-grained layer to fill said pore voids, said supply valve also having a closed position and being configured, in said closed position, to cause a head level of said tap water mixture to fall down to the initial groundwater level, such that at least a portion of the air dissolved in said mixture makes cores of said micro particles of said mineral powder and thereby bubbles out of said mixture to reduce a degree of pore water saturation in said loose fine-grained layer to prevent seismic liquefaction due to earthquake.