Electro-osmotic grouting technique for liquefaction-mitigation of low permeability silty soils
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Electro-osmotic grouting is a new foundation improvement technique proposed to treat low permeability, liquefiable silty soils underneath existing structures for the purpose of liquefaction-mitigation. This technique uses a d.c. current to introduce water soluble grout materials and reactants into the silty soils. Setting time of injected grouts can be controlled by adjusting the concentration and sequence of introduction of various components. Both experimental and numerical studies were performed in this research. Experiments were conducted to prove the feasibility of electro-osmotic injection under 1-D and 3-D conditions, to quantify the increase of liquefaction resistance in silty soils due to electro-osmotic grouting, and to design grout mixes feasible for electro-osmotic grouting. Numerical analyses were performed to simulate grout flows under a 3-D condition, to determine the rate and extent of grout penetration, and to estimate power consumption in electro-osmotic grouting. Study shows that electro-osmotic grouting is a promising technique. Colloidal silica and sodium silicate grouts can be injected into low permeability silty soils at the rate of about 10 -5 cm/s per v/cm, and liquefaction resistance of the silty soils increased significantly after injection.