GROUND IMPROVEMENT CHEMICAL INJECTION METHOD

PROBLEM TO BE SOLVED: To provide a ground improvement chemical injection method which enables specifications of chemical injection to be promptly determined and curbs man-hours and a cost when injecting a chemical into the ground.SOLUTION: A relation between water injection pressure P and an injected water flow rate Q is obtained by injecting water into at least one injection hole constructed in an object area. A water permeability coefficient k of the object area is calculated on the basis of the obtained relation between the injection water pressure P and the injected water flow rate Q. Also, a fine-grain fraction content Fc of the object area is calculated on the basis of the calculated water permeability coefficient k and preliminarily stored data on the relation between the fine-grain fraction content Fc and the water permeability coefficient k. One chemical injection specification corresponding to the calculated fine-grain fraction content Fc is selected from a plurality of chemical injection specifications preliminarily set in accordance with a range of the fine-grain fraction contents Fc. Then, on the basis of the selected chemical injection specification, ground improvement is executed by injecting the chemical into the injection hole where the water is injected and other injection holes around the same.SELECTED DRAWING: Figure 1 【課題】地盤に薬液を注入するに際して、薬液注入仕様を迅速に決定できるとともに工数やコストを抑えることが可能な地盤改良薬液の注入方法を提供する。【解決手段】対象領域に形成された少なくとも１本の注入孔に水を注入することにより、対象領域における注水圧力Ｐと注水流量Ｑとの関係を取得する。そして、この取得した注水圧力Ｐと注水流量Ｑとの関係に基づいて対象領域の透水係数ｋを算出し、この算出した透水係数ｋと、予め蓄積されている細粒分含有率Ｆｃと透水係数ｋとの関係データとに基づいて、対象領域の細粒分含有率Ｆｃを算定する。細粒分含有率Ｆｃの範囲に応じて予め設定されている薬液の複数の注入仕様の中から、算定した細粒分含有率Ｆｃに合致する１つの注入仕様を選択し、この注入仕様に基づいて、水を注入した注入孔およびその周囲の注入孔に薬液を注入し、改良地盤を形成する。【選択図】図１