Axis control method for shield sharp curve construction in upper-soft-lower-hard stratum

The invention provides an axis control method for shield sharp curve construction in an upper-soft-lower-hard stratum. The method comprises the steps that 1, stratum investigation is performed along a shield path; 2, a hat brim device is installed on a shield machine and comprises at least two sets of fixing units, a rotating unit, at least three sets of synchronous telescopic units and a hat brim, the fixing units are installed on the inner side of a shield machine shell, the hat brim is driven by the rotating unit to rotate to any position in the shield machine along the fixing units, and turning and deviation rectifying are continuously adjusted according to the pushing length of the hat brim; 3, the hat brim device controls the shield machine to perform sharp curve construction in the upper-soft-lower-hard stratum. Accordingly, shield axis controlling and axis deviation rectifying become more flexible and freer, the axis controlling quality is improved, and the overexcavation quantity generated by sharp c