ORIGINAL PAPER Analytical Behaviour of Bolt–Joint Intersection Under Lateral Loading Conditions H. Jalalifar Æ N. Aziz Received: 27 October 2007 / Accepted: 7 April 2008 / Published online: 12 February 2009 Ó Springer-Verlag 2009 Abstract An analytical method is developed to provide a better understanding of bolt shearing across joint planes under lateral conﬁnement. The study was undertaken in conjunction with a laboratory study of the double shearing of bolts in concrete. A review of various analytical meth- ods is discussed, and the bending behaviour of the bolts is studied under both elastic and plastic conditions. Issues examined include; hinge point location, the effect of con- crete strength on the bolt-bending behaviour; the inﬂuence of bolt axial loading and bolt diameter on the hinge point position with respect to sheared joint planes. It was found that the applied axial load on the bolt had a signiﬁcant bearing on the location of the hinge points in different strength concrete, particularly at low strengths. The hinge point location is also inﬂuenced by the bolt diameter. Keywords Bolt shearing  Analytical method  Conﬁnement  Joint planes  Axial loading  Hinge 1 Introduction Rock bolts have gained signiﬁcant importance in recent years as the main elements of support in the modern stabilisation techniques for geotechnical engineering. Gen- erally, bolts work as an additional resistance against shear failure along joints and weakness planes. The steel bar within the rock bolt system is the main element to resist both the axial load under suspension conditions and shear load due to beam bending and slip on joints. In case of bending behaviour and the load transfer mechanism of the bolt that is subjected to lateral loading conditions, signiﬁcant research has been carried out for the past several decades. The ﬁrst reported study of bolt shearing was initiated by Dulacska (1972), who tried to examine the level of shear force carried by the bolt, based on the idealised stress distribution at the encapsulated bolt surface. Her theory was based on the development of a plastic hinge at the point of maximum bending moment. Dulacska was then followed by Bjurstrom (1974) on the shear testing of cement-grouted bolts in granite blocks, examining the inﬂuence of various factors affecting the shear strength of rock joints. The bolts had inclinations of between 30° and 90° with respect to the joint surface. Bjurstrom found that, for an installed angle of less than 40°, the bolts failed in tension, and for angles greater than 40°, they failed in a combination of both shear and tension. Dight (1982), in a study on the theoretical analysis of the grouted bolt perfor- mance, assumed that the bolts’ contribution to the strength of a sheared joint was the resultant of the tensile force in the bolt and the dowel effect. Pellet and Egger (1996), in an analytical model for the contribution of bolts to the shear strength of a rock joint, took into account the interaction between the axial and shear forces mobilised in the bolt with large plastic displacements of the bolt occurring during the loading process. The description of the bolt behaviour was divided into two sections. The ﬁrst concerned the elastic range (from the beginning of the loading process) and the second dealt with the plastic range (from the yield to the failure of the bolt). Tresca’s criterion of failure was used for the bolt. Pellet and Egger’s theory is valid for the inclined bolts of less than 90° and is not acceptable for bolts sharply perpendicular to the joints. Also, they developed an H. Jalalifar (&) Shahid Bahonar University of Kerman, Kerman, Iran e-mail: jalalyfar@yahoo.com N. Aziz Wollongong University, Wollongong, NSW, Australia 123 Rock Mech Rock Eng (2010) 43:89–94 DOI 10.1007/s00603-009-0032-6