Abstract:Taking a DN1200 water supply pipeline project in Nansha District, Guangzhou as an example, the difficulties encountered when crossing long-distance river channels are analyzed. The directional drilling scheme is finally determined through the comprehensive comparison from multiple aspects. combined with the engineering practice, the precise dual guidance system is used to control the spatial positioning of the pipeline, the speed reduction and pressure reduction are prepared in advance, and then the holes are cleaned to deal with the uncontrolled mud leakage in the guide hole. The special tools are equipped to deal with the jamming and drilling package of pre-expansion hole. The mud ratio and mud pressure are adjusted to prevent the difficulties such as hole collapse and mud overflow. Aiming at the problem of large net buoyancy of the pipeline during the back dragging process, an internal water filling method is adopted for counterweight anti-floating. The minimum wall thickness of the pipeline is determined through calculation to ensure that the pipeline does not experience the detachment and damage during the back dragging process. The reasonable back-dragging drilling tools and related measures are taken to ensure the smooth process of pipeline dragging back. The pipeline has been successfully completed with the good trial operation, which can provide the useful reference for similar projects.
