Mineralogical, Mechanical, and Electrical Properties of Clays and Their Relation to Clogging during Mechanical Tunnel Driving

Abstract

One of the problems that can occur while boring through fine-grained soil is the adherence of clay to the EPB cutting wheel, inside the excavation chamber or in the transportation line, which might lead to long delays in the progress. Since the economic success of a tunneling project depends highly on the clogging potential of the encountered clay formations, it is of vital importance to understand this phenomenon and find possible solutions. Currently, there is no effective soil conditioning technique based on scientific data. Aim of this paper is to show how the mineralogical properties of clays play an important role for the mechanical and adhesive response. Mechanical laboratory tests, zeta (ζ) potential measurements, calculations and clogging tests were performed in order to link the adhesive properties with the clay mineralogical composition.

Clogging Risk Early Warning for Slurry Shield Tunneling in Mixed Mudstone–Gravel Ground: A Real-Time Self-Updating Machine Learning Approach

“…As clogging results from the adherence of the excavated clayey soil, it is influenced by the properties of clay soil and the slurry flow behavior [2,12]. Experiments have assessed the possibilities of clogging in one specific kind of soil and slurry flow behavior [2,[12][13][14][15][16]. They allowed the establishment of some direct and indirect methods for clogging judgment.…”

Assessment of the clogging potential of two clays

“…Clogging is a phenomenon that occurs because cohesive materials tend to adhere to cutting tools at the cutterhead, openings of the cutterhead, screw conveyor, or conveyor belt. This, in turn, can lead to severe problems in tunnelling projects, including excavation difficulties, an extension of the project timetable and, consequently, budget overrun (Thewes, 1999;Spagnoli et al, 2014;Thewes and Hollmann, 2014;Zumsteg et al, 2016;Oliveira, 2018). Clogging is a result of the attraction between soil particles and a foreign object, as well as adhesion between water in the soil and the object (Fountaine, 1954;Lal and Shukla, 2004;Zhang et al, 2018).…”