Injection process and injection apparatus for solidifying a ground

An injection apparatus for solidifying a soft ground or preventing water-leaking ground from water leakage by injecting a blend of water glass type grout thereinto, wherein said blend comprises a non-alkaline aqueous solution of silicic acid which is obtained by mixing water glass into an aqueous solution of an acidic reactant so as to remove alkali from said water glass, said non-alkaline aqueous solution of silicic acid being prepared to meet both of the following conditions A and B:

• A. the pH valve thereof is 5 of less;
• and
• B. a value of H+/(SiO.sub.2).sup.n is 1.times.10.sup.-3 or less;
• where (H+) is the molar concentration of hydrogen ions, (SiO.sub.2) is the molar concentration of silicon dioxide, and n is the molar ratio of said water glass, said apparatus comprising a mixing mechanism for preparing a non-alkaline aqueous solution of silicic acid, an injection pipe mechanism to be provided in the ground for injecting said aqueous solution thereinto, and a conveying mechanism interposed between said mixing mechanism and said injection pipe mechanism for conveying said aqueous solution from said mixing mechanism to said injection pipe mechanism, in which said mixing mechanism comprises:
• material containers for containing materials for preparation of said non-alkaline aqueous solution of silicic acid;
• a mixing container connected through pipes to said material containers, said mixing container being adapted to prepare said non-alkaline aqueous solution silicic acid by adding and mixing water glass into aqueous solution of acidic reactant therein;
• a supplying mechanism provided in each of said pipes, for supplying said materials in said material containers to said mixing container, thereby to prepare the non-alkaline aqueous solution of silicic acid by adding and mixing water glass into aqueous solution of acidic reactant in the mixing container.