DRIVING FORCE PREDICTION IN MICROTUNNELING TECHNOLOGY WITH SLURRY SHIELDS: ESTIMATION OF END FORCES AT TUNNELING SHUTDOWNS—II

Prediction of driving forces is a requisite procedure in tunneling design in water-saturated ground using technology of microtunneling with slurry shields. In this regard, the commonly known increase in the driving force in restart of work after shutdowns is never represented in regulator documents. It is necessary to study physical process, in particular in the contact zone of slurry shield and soil, which induce an increase in starting resistance of the slurry shield tunneling system. The model is constructed to describe formation of ends forces of starting resistance in time in the driven system in straight-line portions in the period of tunneling shutdown given the shield clearance is filled with mixture of water and weight material (soil–bentonite slurry or foam soil paste). These forces are governed by the tunneling machine weight transferred to the ground matrix. The model is based on solution of the two-dimensional approximated contact problem on filtration consolidation for a rigid cylinder pressed by its own weight to a layer of material in the shield clearance with regard to fluid flow in this layer and to fluid outflow to enclosing ground. The relations are derived for the initiation force of starting resistance versus duration of the tunneling shutdown for different integrated time parameters determined by consolidation coefficient of material in the shield clearance and by the hydraulic resistance of soil. The obtained results enable more accurate analysis of the friction component of driving forces and their sensitivity to change in the tunneling process parameters.


For citation: Shornikov I. I. Driving force prediction in microtunneling technology with slurry shields: Estimation of end forces at tunneling shutdowns—II. MIAB. Mining Inf. Anal. Bull. 2019;(7):42-52. [In Russ]. DOI: 10.25018/0236-1493-2019-07-0-42-52.

Keywords

Tunnel casing, shutdown, water-saturated soil, driving force, friction component, starting resistance end force formation, slurry shield subsidence, shield clearance, slurry shield—clearance material—soil contact zone, consolidation coefficient, hydraulic resistance, AVN slurry shields.

Issue number: 7
Year: 2019
ISBN: 0236-1493
UDK: 622.02: 624.1
DOI: 10.25018/0236-1493-2019-07-0-42-52
Authors: Shornikov I. I.

About authors: I.I. Shornikov, Cand. Sci. (Eng.), Assistant Professor, Mining Institute, National University of Science and Technology «MISiS», 119049, Moscow, Russia, e-mail: shornicovivan@gmail.com.

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