The invention discloses a rock foundation existing high-speed
railway embankment force balance assisting widening structure and a construction method. The assisting widening structure comprises a plurality of grouting anchor rods, a
reinforced concrete frame structure, a
reinforced concrete cantilever plate and a filling body, wherein the plurality of grouting anchor rods are used for being arranged in a rock foundation outside a slope foot of an existing embankment at intervals, the
reinforced concrete frame structure is used for being arranged on the rock foundation outside the slope foot ofthe existing embankment, all the grouting anchor rods are connected to the bottom of the frame structure, one end of the reinforced concrete
cantilever plate is connected to the top of the frame structure, the other end of the reinforced concrete
cantilever plate is arranged on an existing embankment road shoulder structure, the top surface of the frame structure, the top surface of the cantilever plate and the top surface of the existing embankment are flush, and the filling body fills a cavity in the frame structure. By using the assisting widening structure, the high
bearing capacity and anchoring force of the rock foundation are fully utilized, the weight of the frame structure and the internal filling body of the frame structure are utilized, pulling force generated by the grouting anchor rods is combined, and load acting on the cantilever plate by a
train is resisted, so that adverse vertical deformation generated when the
train passes through the cantilever plate can be avoided, and an existing high-speed railway is not influenced.