An injection process for solidifying a soft ground by injecting a blend of water glass type grout thereinto which is a non-alkaline aqueous solution of silicic acid obtained by the mixing water glass into an aqueous solution of acidic reactant so as to remove alkali from the water glass, and an injection apparatus for practicing the injection process which comprises a mixing container for preparing the non-alkaline aqueous solution of silicic acid by adding and mixing the water glass into the aqueous solution of acidic reactant.