engleski

Design of Micro-tunnel Path for Pipeline on Wheel Supports

Micro-tunneling is a modern trenchless method for construction of underground utilities, particularly in urban areas. A micro-tunnel can be built as an arc beneath the obstacles on the ground. In this case, insertion of steel pipelines into the existing tunnel presents a considerable technical problem, especially when the tunnel path has sudden changes in curvature or significant deviations from the designed path. Lifting of the supports during the insertion process, due to the path unevenness, leads to the unilateral contact problem. Thus, both the load of the supports in contact and stresses in steel pipes are increased. Also, high value of local curvature of the tunnel results in increased stresses in pipes and additional insertion problems. Because of that, in this paper a new design of tunnel path with gradual change in curvature is proposed and analyzed. Analysis is conducted on the basis of the previously developed computational model which solves the unilateral contact problem iteratively and treats the pipes as uniformly loaded elastic beams supported by a finite number of stiff supports. A particular problem is the micro-tunnel under the Sava River. In this case study it is shown how the predefined path of a micro-tunnel influences the stresses in pipes and loads of wheel supports during the insertion process and exploitation.

micro-tunnel path ; steel pipeline ; insertion process ; support load ; pipe stresses

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