Closed-form solution for plastic zone formation around a circular tunnel in half-space obeying Mohr-Coulomb criterion

Massinas, SA; Sakellariou, MG

dc.contributor.author	Massinas, SA	en
dc.contributor.author	Sakellariou, MG	en
dc.date.accessioned	2014-03-01T01:29:59Z
dc.date.available	2014-03-01T01:29:59Z
dc.date.issued	2009	en
dc.identifier.issn	0016-8505	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/19433
dc.subject	Design	en
dc.subject	Excavation	en
dc.subject	Plasticity	en
dc.subject	Soft rocks	en
dc.subject	Stress analysis	en
dc.subject	Tunnels	en
dc.subject.classification	Engineering, Geological	en
dc.subject.classification	Geosciences, Multidisciplinary	en
dc.subject.other	PLANE	en
dc.title	Closed-form solution for plastic zone formation around a circular tunnel in half-space obeying Mohr-Coulomb criterion	en
heal.type	journalArticle	en
heal.identifier.primary	10.1680/geot.8.069	en
heal.identifier.secondary	http://dx.doi.org/10.1680/geot.8.069	en
heal.language	English	en
heal.publicationDate	2009	en
heal.abstract	A closed-form solution for the problem of the plastic zone and stress distribution around a circular tunnel in an elastic-plastic half space, derived using bipolar coordinates, is the main scope of this paper. By assuming a uniformly applied surface loading, the whole semi-infinite space is under uniform pressure: thus the gravitational effect is neglected, while the plastic zone formation around the circular tunnel is controlled by the applied internal support pressure. The plastic behaviour of the half space is described by the Mohr-Coulomb yield criterion, and the soil is assumed to be homogeneous and isotropic with earth pressure coefficient K-0 equal to unity. The critical internal pressure, where the initial yielding occurs at the tunnel wall, is derived, along with equations describing the plastic zone and plastic stresses. These equations are functions of the soil properties, which are cohesion and friction angle. This derived closed-form solution is validated through mathematical and computational analysis, and is also compared with numerical models under gravitational load, solved using the finite difference method. This innovative closed-form solution has a significant impact in practical problems by introducing a simple and effective method that allows the quick estimation of a shallow tunnel's behaviour, since it gives, in principle, the opportunity for quick and accurate calculation of the plastic zone and stress distribution around the circular tunnel. By applying different values of support pressure, the tunnel designer can easily evaluate the feasibility of different design alternatives, such as shotcrete shell and tunnel-boring machine support pressure. As a result, an efficient and innovative method of solving shallow tunnelling problems in cohesive-frictional soil is introduced.	en
heal.publisher	THOMAS TELFORD PUBLISHING	en
heal.journalName	Geotechnique	en
dc.identifier.doi	10.1680/geot.8.069	en
dc.identifier.isi	ISI:000271485200005	en
dc.identifier.volume	59	en
dc.identifier.issue	8	en
dc.identifier.spage	691	en
dc.identifier.epage	701	en