Innovative Trenchless Solutions For Pipeline Crossings And Landfalls
In pipeline construction, occurring obstacles have to be crossed. A further challenge is the offshore-onshore connection of pipelines. This includes the landfalls of oil and gas pipelines as well as cables, water or sewage lines. These kinds of projects require specialized construction techniques with minimum environmental impact. In the planning stage of a pipeline crossing project, all surrounding conditions have to be analyzed to find the safest and most cost-efficient method to be deployed. Besides technologies made especially for the pipeline industry, like the proven HDD method, there is a growing number of alternative pipeline installation techniques, which partly come from the tunnelling industry. Whereas some of the technologies install the product pipeline directly into the borehole (e.g. HDD, Direct Pipe®, Pipe Express®), others install casings in which the pipeline is pulled-in in a further step, e.g. by a Pipe Thruster. In most cases, pipeline casings are installed using Pipe Jacking and Segment Lining Tunnelling equipment, depending on crossing length, diameter and geology. By using Pipe Jacking equipment, it is also possible to jack steel product pipes. With the development of a downhole jet pump system for HDD operations, Herrenknecht has extended the application range of existing technologies. In conjunction with a new HDD tooling series, the downhole jet pump system allows drilling and cutting faster at lower cost and risk. Furthermore, it enables longer drives in smaller diameter for Pipe Jacking and Direct Pipe®. The newly developed AVNS tunnelling machine (minimum ID 350mm), with small powerpack and slurry jet pump in the machine, is designed for up to 1,000m drive length, depending on geological conditions. It can also be used for Direct Pipe® to open up the range from 20” to 30” (formerly defined diameter 30” to 60”). This paper presents innovative pipeline construction methods and selected case studies.