Method for stably fixing first-section pipe section of super-large-diameter GRP pipeline under water

The invention relates to a construction process, in particular to a method for stably fixing a first-section pipe section of a super-large-diameter GRP pipeline under water. The method for stably fixing the first-section pipe section of the super-large-diameter GRP pipeline under water comprises the following steps of S1, lowering a first-section first section pipeline; S2, lowering a sand box and fixing a pipeline; S3, lowering the adjacent first-section secondary section pipeline; S4, repeating the step S2; S5, mounting diagonal bracings; S6, repeating the steps S1-S5; S7, back-filling gravels; and S8, removing the sandbox and the diagonal bracings. According to the method for stably fixing the first-section pipe section of the super-large-diameter GRP pipeline under water, transverse displacement of the pipeline is limited in the mode that the sand box is matched with the lead screw; and meanwhile, rolling displacement of the pipeline is limited through the diagonal bracings; and finally, gravels are back-filled to enable the whole pipeline to be stably fixed; and therefore, the first-section pipeline can be kept stable underwater, the mounting precision of the first-section pipeline is guaranteed, and the mounting requirements of subsequent pipelines can be met; and the construction quality is guaranteed and greatly improved, the process is direct and effective; and fixing members such as the sandbox and the diagonal bracing can be recycled, so that the construction cost is greatly reduced, and the construction period is shortened.