CONSTRUCTION METHOD FOR PRE-STRESSED PULL-RESISTANT ANCHOR ROD OF CONCRETE EXPANSION HEAD

A construction method for a pre-stressed pull-resistant anchor rod of a concrete expansion head, comprising the steps of: 1) movably pressing a steel casing (13) against a pile end anchor (14) and sinking same down together to a set depth, wherein a steel strand (16) is fixedly connected to the pile end anchor (14), and a protective tube (17) fixed on an anchor plate (141) is sleeved on the steel strand (16); 2) pouring fine stone concrete (20) between the steel casing (13) and the protective tube (17); 3) lifting the steel casing (13) upward and inserting same downward repeatedly, so that the fine stone concrete (20) flows out of the steel casing (13) to gradually form a concrete expansion head (21); continuously pouring the fine stone concrete (20) to form a pile body of a set height in the steel casing (13); 4) pulling out the steel casing (13); and 5) excavating earthwork to a set depth, and once the concrete expansion head (21) reaches a curing period, tensioning and locking the steel strand (16). The co