26 Trenchless Pipe-Paving in Complex Hard Stratum by Directional Drilling Technology

As we all know, it is very difficult to pave any pipe in a complex stratum involving hard stratum, middle-hard stratum and backfilling stratum especially for the narrow space for directional drilling machine. However, a pipe-paving project for waste hot water drainage was fulfilled successfully by the author and his colleagues last year. Based on that experience, many new key high-technologies and measures used in that project are introduced in this paper such as the wireless navigation, the hydraulic correction, the forward direction reaming and the drilling with a tube followed. That project shows the pipe-paving project using a small trenchless rig in the narrow place could be finished successfully in the complex stratum of the hard rock and the mid-hard rock with some high new technologies. And the first application of the hydraulic correction technology combined with the machinery and waterpower is very successful. In that project, a special reaming bit is adopted for the forward reaming both in hard and mid-hard rock. The self-made electropult and receiver of the electromagnetic wave is so stable, reliable, and accurate that can satisfy the requirements of the trenchless pipe-paving navigation well.