Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

Quarterly Journal of Engineering Geology & Hydrogeology

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by West, G. Articles by Pettifer, G.S. Search for Related Content GeoRef GeoRef Citation

Discussion of ‘Destructuring and disaggregationof Mercia Mudstone during full-face tunnelling’ byJ H Atkinson, P G Fookes, B F Miglio & G S Pettifer Quarterly Journal of Engineering Geology and Hydrology, Vol. 36, 293–303

¹ 17 Tithe Court, Glebelands Road, Wokingham, Berkshire, RG40 1DS, UK
² Geotechnical Engineering Research Centre, City University, London EC1V 0HB, UK
³ 'Lafonia', 11A Edgar Road, Winchester, Hampshire, SO23 9SJ, UK
⁴ Ove Arup and Partners, 13 Fitzroy Street, London, W1P 6BQ, UK
⁵ 83, Langdale Avenue, Mitcham, Surrey, CR4 4AJ, UK

The first 20% of the full text of this article appears below.

	Introduction

 
Graham West writes: Messrs Atkinson, Fookes, Miglio and Pettifer are to be congratulated on their paper which addresses an important geotechnical problem, namely the breakdown of aggregations in the Mercia Mudstone and the effect this has on the physical properties of the material and the consequences for civil engineering operations. The work described parallels investigations of the Keuper Marl (as the Mercia Mudstone was then called) made during the 1960 s in which I was involved, and the purpose of this Discussion is to compare and contrast the findings of these two pieces of work. The earlier work was concerned with highway construction and the present work is concerned with tunnellingbut there are many points of common interest. The Discussion focuses on three main topics: (1) the breakdown of coarse aggregations, (2) the stability of fine aggregations, and (3) the clay mineralogy.

During the 1960 s much of the new motorway construction in southern Britain took place over the outcrop of the Mercia Mudstone (Dumbleton & West 1966a). Generally, the material encountered was a weak mudstone, but it was found that after excavation, transport, spreading and compaction on site it broke down to the condition of a clay. Because of this the then Road Research Laboratory carried out an investigation of the mineralogy and physical properties of the material.

The conditions of working of the Mercia Mudstone by a tunnel boring machine in a tunnel site are probably more aggressive than by earthmoving plant on a motorway site.

	Breakdown of coarse aggregations

 
Atkinson et al. found that coarse aggregations of the Mercia Mudstone broke down readily under the mechanical action of the cutting head of the full-face tunnel boring machine, this effect being exacerbated where inflow of groundwater took place causing the mudstone to be reduced to a plastic clay, a sticky . . . [Full Text of this Article]