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A New Approach for Determination of Adhesion Coefficient in Pipejacking Method by Experimental and Numerical Analysis: An Example from Istanbul



The common technique used for the construction and maintenance of infrastructure facilities until recently involved traditional open excavation methods. Technological advancements and developments in gathering geotechnical information on our working environment have given birth to the development of new methods which will prevent problems that may have emerged due to the use of traditional methods during the construction of infrastructure facilities. One of these new methods is trenchless technology which is becoming increasingly popular in the infrastructure construction industry. One of its processes, the pipejaking process, is of special importance in busy urban centres and densely populated living quarters as it has proved to be the most sustainable method for working in such environments and for global use. The name of this process is trenchless technology. There is an increasing demand for infrastructure systems, especially in cities, because of increasing populations and varying lifestyles, and in the areas around cities which are environmentally sensitive. Routes of infrastructure (pipelines) to be constructed have many obstructions such as motorways, buildings, railways, rivers, creeks, and canals. The pipejacking process, a trenchless technology to overcome these problems and obstructions, has been achieving an important scope of application in Turkey and the rest of the world. Infrastructure facilities planned to be constructed by the application of this system can be built under every kind of ground condition in a correct, swift, and economic manner, without needing an open excavation and its associated traffic problems and conditions that may cause danger to human life and property. Within the context of this study, the collector line, constructed in Şile district by the pipejacking process (which is 1535 m in length and 800 mm in diameter), was examined, and jacking force length graphics were prepared with the use of jacking force records obtained from the machine. After analysing these graphics, change of coefficients of α adhesion was researched and, for use at cohesioned grounds, an α value was suggested in order to predict friction resistance and accordingly possible jacking force values that may be faced. First, with the assistance of the Plaxis 3D Tunnel Program, considering land conditions, the examined line was modelled. Then, stress values resulting from this modelling and graphic analyses were compared, and observed harmonies or inharmonies were discussed. Lastly, parameters that are effective on these harmonies or inharmonies were defined. In addition, considering jacking forces and stress values observed where bentonite is whether used or not, the lubricant's effect on the jacking action was examined. Within the context of this study, stoppages, lubrication during jacking process, and their effects on the jacking force and stresses were analysed. Thus, a versatile study regarding the pipejacking process has been put forward for consideration.