The invention relates to the technical field of high-speed rail 
tunnel construction, and particularly relates to a dismounting and replacing construction method for an inverted arch of a floor heave section of a high-speed rail tunnel. The method comprises the following steps that S1, a track is dismantled, fasteners are collected and picked up, and equipment protection of a dismounting and replacing section is conducted; S2, a 
ballast bed is 
cut by a disc saw; S3, the 
ballast bed is hoisted to a 
slag yard, specifically, the whole 
cut ballast bed is hoisted to a flat plate transport vehicle through an 
excavator and is cleared and transported to a waste 
slag yard outside the tunnel; S4, a trestle is erected, and specifically, the trestle is erected on the excavation section in a suspended mode; S5, the side wall is reinforced with an anchor rod; S6, drainage ditches on the two sides and an inverted arch filling layer at the end are 
cut; S7, side wall joint 
cutting is conducted, and an arch frame is installed; S8, the inverted arch, the ditches and the filling layer are chiseled away and excavated; S9, base concrete spraying construction is conducted; S10, a waterproof layer is installed, reinforcing steel bars are installed in a bound mode, and concrete is poured; S11, 
ditch cable troughs on the two sides and a ballastless 
track bed plate are recovered; and S12, the next inverted arch replacement section is constructed. According to the method, the inverted arch dismounting and replacing efficiency is high, and the working intensity is relieved. The method is mainly applied to dismounting and replacing of the inverted arch of the tunnel floor heave section.