Trenchless Excavations for Underground Pipelines in Difficult Geology

Geotechnical Engineering Journal of the SEAGS & AGSSEA ISSN 0046-5828

Vol. 49 No.2 June 2018

Trenchless Excavations for Underground Pipelines in Difficult Geology

By Keh-Jian Shou, Jonas Yen, and Chih-Ying Hsieh

ABSTRACT: No-Dig constructions in the city might encounter various difficulties. And the difficulties or obstacles, which might cause schedule delays and damage to the pipes. Among the others, the conditions of overcut and stuck could be the most common and critical to a pipejacking project. This study considered various difficult conditions, including different overcut range and sticking position, together with different resistance, jacking force, etc. The ABAQUS finite element software was applied for three-dimensional numerical simulations for pipe-jacking with different difficult situations. The analyses focused on the pipejacking in gravel formations, and the suggestions were concluded based on the results. The results suggest that the location of sticking and its severity (different frictional coefficient was set) affect the stress field in the pipe. And the worst condition, i.e., the totally stuck, the adjacent soil and pipe will experience excessive deformation, which must be avoided. Therefore, lubrication to avoid this extreme scenario is essential in the pipejacking operation. For the case with large diameter, unavoidable overcut and highly variable geology, the above suggestions are more crucial.

KEYWORDS: Pipejacking, No-Dig, Difficult geology, Numerical analysis, Soil-pipe interaction