Unstressed installation and adjustment construction method forvertical inhaul cable of fork ear type anchorage device

The invention provides an unstressed installation and adjustment construction method for a vertical inhaul cable of a fork ear type anchorage device. The method comprises the following steps: calculating and measuring unstressed cable length, dismantling a steel arch bracket, installing and welding box girder fork lugs, accurately measuring coordinates of the fork lugs, assembling inhaul cable connecting components, initially installing inhaul cables, marking inhaul cable parameters, dismantling a main girder bracket, tensioning cable force, paving a bridge deck and secondarily tensioning the cable force; and meanwhile, carrying out tracking, detecting and correcting, obtaining a cable force unified measurement result, and completing installation of the inhaul cable. According to different stress of each section of the steel arch, the lengths of the unstressed initially-installed inhaul cables are calculated respectively, and in-plant locking control is carried out; and during installation, adjustment is carr