Construction method for underground continuous walls in large-fluctuation rock surface stratum

The invention provides a construction method for underground continuous walls in a large-fluctuation rock surface stratum in order to effectively reduce the groove bottom rock breaking workload, shorten the underground continuous wall grooving construction period, reduce the engineering cost, decrease the necking and hole collapse risks caused by too long waiting time to an upper weak stratum segment, avoid a water-stop curtain weak link caused by a large quantity of sediment, and ensure the construction quality and safety of the underground continuous walls. The construction method comprises the following steps that three advance boreholes are spaced within the width range of each underground continuous wall according to the accurate positions of the underground continuous walls, the groove bottom rock surface trend and distribution condition are judged according to the hole termination depth of the advance boreholes drilled to the rock surface, and the geological rock surface condition is precisely judged;