Pipe jacking and microtunnelling

Research on jacking loads, pipe–ground interaction and excavation performance for trenchless pipeline construction in complex ground conditions.

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Pipe jacking and microtunnelling operations

Research context

Microtunnelling operations allow pipelines to be installed from jacking pits. Trenchless operations such as microtunnelling minimise trench spoil and therefore reduce waste. Compared with conventional trenching, they also reduce damage to road surfaces and disruption to traffic.

During the microtunnelling process, the jacking load is an important design parameter. It controls pipe-wall thickness, the need for and location of intermediate jacking stations, jacking-frame selection and lubrication requirements. The principal component of the jacking load is frictional resistance.

Microtunnelling is a complex process, making the theoretical determination of jacking forces challenging. Pipe–soil and pipe–rock interaction is strongly affected by excavation conditions, including overcut, lubrication, pipe misalignment, stoppages, tunnel stability and rock-mass quality.

Research objectives

Research in this field aims to improve design and analysis techniques for pipe-jacking and microtunnelling operations, with particular attention to the following subjects.

RESEARCH SUBJECT 01

Pipe jacking in swelling clays

This work investigates jacking forces and pipe–soil interaction in swelling clay conditions. The research was conducted in cooperation with the University of Cambridge.

RESEARCH SUBJECT 02

Microtunnelling in fractured rock masses

This research examines how rock-mass discontinuities, excavation stability and construction conditions affect microtunneller performance and the jacking forces required for advancement.

RESEARCH SUBJECT 03

Applications in the Torino subsoil

Investigation, interpretation and design methods are developed for the Torino metropolitan area. A discontinuum numerical model supports correlations between subsoil geotechnical characteristics and microtunneller requirements, including the jacking force needed for advancement.