Bolt action in jointed rock

32A 851282 Proceedings of the International Symposium on Rock Bolting, Abisko, 28 August-2 September 1983 Stephansson, O (editor) Rotterdam: A. A. Balkema. 1984, 630P 851283 Rock bolting in theory. A keynote lecture Gerrard, C Proc International Symposium on Rock Bolting, Abisko, 28 August-2 September 1983 P3-32. Publ Rotterdam." A. A. Balkema, 1984 Indicates current directions in research into the theoretical aspects of rock bolts. The assumptions to be considered in developing mathematical models to represent bolted rock masses relate to: (1) the inherent uncertainty in geotechnical parameters, (2) the time dependent aspects, and (3) the discrete character of the bolts and the surfaces of weakness and softness in the rock mass. 91 refs. 851284 Bolt action in jointed rock Larsson, H; Olofsson, T Proc International Symposium on Rock Bolting, Abisko, 28 August-2 September 1983 P33-46. Publ Rotterdam: A. A. Balkema, 1984 A constitutive elasto-viscoplastic model is presented which combines the properties of the jointed rock mass and the rock bolt system. Different mechanisms of single joint-bolt systems are analysed. Mechanisms like axial straining, tensionstiffening (due to bonding between grouted bolts and rock) and dowel action are included in the model. Stiffness properties are derived from pull-out tests on single bolts. The various stiffnesses and compliances from multi-directional joint sets and bolt sets are superimposed with intact rock properties in a model of the rock mass. The contribution from each set of joints and bolts are added and distributed over a certain volume of rock. This makes the model easy to implement into finite element systems. Finally, the model is used to analyse some simple bolt systems in jointed rock. Auth. 851285 Predicted response of two cases of reinforced jointed rock Gerrard, C: Pande, G Proc International Symposium on Rock Bolting, Abisko, 28 August-2 September 1983 P47-53. Publ Rotterdam: A. A. Balkema, 1984 A previously published mathematical model for reinforced jointed rock is used to predict the effect of the controlling variables on the mechanical response of two practical examples. These examples are a bolted rock pillar, subject to compression, and a bolted set of joints, subject to shear. The mathematical model is based on an elastic/visco-plastic algorithm that enables variations in the rock joint orientation, compliance, strength, and flow properties to be considered, as well as the amount, orientation, strain hardening, stiffening, and prestress of the reinforcement. Results are presented that indicate how such variables influence the strength and compliance for the two practical examples investigated. Auth. 851286 Theoretical aspects on the difference between prestressed anchor bolt and grouted bolt in squeezing rock Stille, H Proc International Symposium on Rock Bolting, Abisko, 28 August-2 September 1983 P65-73. Publ Rotterdam: A. A. Balkema, 1984

851287 Studies of the composite system of rock mass and nonprestressed grouted rock bolts Wullschlager, D; Natau, 0 Proc International Symposium on Rock Bolting, Abisko, 28 August-2 September 1983 P75-85. Publ Rotterdam: .4. A. Balkema, 1984 The paper deals with the self-supporting ring, formed by nonprestressed fully grouted rock bolts and the surrounding rock mass, around an extended cavity in squeezing rock. The selfsupporting ring is considered as a separate statical system. To determine the global strength properties of this composite system studies of the stress-strain behaviour of an idealized ring element consisting of bolts and the rock mass were made. Results from variations of geometrical parameters obtained from model tests and finite element calculations are presented. They confirm the exponential increase of the system strength when the bolt distance decreases linearly. 851288 Behaviour of rock bolting as tunnelling support Tao Zhen Yu; Chen Jie Xian Proc International Symposium on Rock Bolting, Abisko, 28 August-2 September 1983 P87-92. Publ Rotterdam: A. A. Balkema, 1984 The most commonly used rock bolt in China is the cementgrouted reinforcing bar. The paper examines the stress state in just such a rock bolt. A three-element rheologic model in which the rock is modelled as a viscoelastic medium is then used to examine the role of bolting in tunnel support. The support mechanism of a shotcrete with bolts system in a weak rock is also considered. 851289 Grouted rock bolt used in underground engineering in soft surrounding rock or in highly stressed regions Sun Xueyi Proc International Symposium on Rock Bolting, Abisko, 28 August-2 September 1983 P93-99. Publ Rotterdam: A. A. Balkema. 1984 A mechanical model, based upon theology, of a single shotcreted bolt is developed using data from in situ observations. The supporting effects of a bolt complex in a gallery are analysed. 851290 Passive anchor reaction to shearing stress in a rock joint Gaziev, E G; Lapin, L V Proc International Symposium on Rock Bolting, Abisko, 28 August-2 September 1983 PIOl-I08. Publ Rotterdam: A. A. Balkema, 1984 Deformation of a passive steel anchor at a sheared joint interface is discussed and an expression for determining the optimum angle of anchor attachment is given. 851291 Theoretical aspects of rockbolting system and rock massif interaction Bulitchev, N S; Kolin, D I Proc International Symposium on Rock Bolting, Abisko, 28 August-2 September 1983 P109-112. Publ Rotterdam: A. A. Balkema, 1984