A new pressure gradient model of slurry shield pipeline system coupling with rheological properties and wall slip behaviour under sandy stratum

Abstract

Pipeline transport is of uttermost importance during slurry shield tunneling, and the precise calculation of the pressure gradient of the pipeline system is the premise for the optimal design of industrial slurry pipeline system. This paper proposed a new muck slurry pressure gradient model of slurry shield pipeline system coupling with the wall slip behaviour based on the Herschel-Bulkley rheological model (H-B model) to estimate the pressure gradient of the muck slurry under sandy stratum. Effects of the sands volume fraction and average particle size on the rheological properties of the muck slurry in pipeline system were investigated to construct the H-B rheological parameters prediction models, which were coupled into the proposed pressure gradient model. Besides, the accuracy and dependability of the proposed model were validated through the engineering field tests and model tests, and the prediction results of the proposed pressure gradient model has an average error of 10.6% and 8.2% with engineering field test data and model test data respectively. The results indicated that the muck slurry is a typical thixotropic fluid. The sand volume fraction and particle size both significantly affect the rheological properties of the muck slurry, the yield stress and plastic viscosity of H-B rheological parameters increase exponentially with the sand volume fraction increasing and increase linearly with the average particle size increasing, the power law index of H-B rheological parameters increases linearly as average particle size and sands volume fraction increase. Ultimately, the research results can provide reasonable suggestions and references for the designing of pipeline system and efficient tunneling of slurry shield.