Long auger rotary-jet mixing steel reinforced cement-soil pile foundation pit water-resisting and supporting method

The invention relates to a long auger rotary-jet mixing steel reinforced cement-soil pile foundation pit water-resisting and supporting method. An undisturbed soil layer is subjected to rotary-jet mixing on the spot through using the characteristic that a transformed long auger drilling tool with a bit is more adaptive to harder pans, the undisturbed soil layer is stirred and filled with grout at the same time to the designed elevation, the long auger drilling tool is pulled out to finish the construction of the cement-soil piles, and then reinforced materials such as shape steel are inserted into the top ends of the cement-soil piles to form columnar reinforced cement-soil pile bodies with certain strength and anti-permeability performance. The method has the advantages that the pile bodies can be driven in the harder pans to the designed depth and the designed pile diameter; through the occlusion of the pile bodies, the closed continuous pile wall body can be formed, and the reliability of a waterproof curtain is improved; and in order to increase the rigidity and the strength of the pile wall body, cement-soil is mixed and then inserted into the reinforced materials such as the shape steel, so as to ensure water-resistance reliability and the foundation pit safety. The method is applied to wide stratum ranges, and has superior advantages in harder pans in northern areas. The shape steel, an anchor rod or an inner support can be recycled, so that the cost is reduced.