A computer method for stability analysis of caverns in jointed rock

Abstract

A simple rigid block model has been developed for analysing the stability of caverns and tunnels in jointed rock. Rigid block interactions are idealized as linear edge-to-edge contacts with a zero joint tension constraint and a Mohr-Coulomb friction law. In the method, the minimum friction angle for stability is determined by sequentially eliminating tension and then minimizing the shear. It is demonstrated through examples that the minimum joint friction angle which results in a stable configuration is independent of the stiffness of the joint, and depends only upon the loading and geometry of the jointing and cavern. This insensitivity of stability to the normal and tangential joint stiffnesses, which can be difficult to obtain, is very useful for design purposes.

Scaling of geological discontinuity normal load–deformation response using fractal geometry

“…However, some data has been reported that can be used to discern the e!ects of scale on shear sti!ness. Experience with testing of discontinuities, and examination of data reported in the literature (see, for example, Reference [17]) shows that interface normal sti!ness and interface shear sti!ness are very closely correlated, where the normal sti!ness is usually between being equal to the shear sti!ness, to being about two orders of magnitude larger. Of course, this is not entirely surprising since both normal and shear sti!ness are a result of the same physical mechanism, namely elastic deformation of asperity material.…”

“…is customarily referred to as the interface sti+ness, and it has units of pressure/length, or force/length. Values of for a variety of joint surfaces in many types of rock have been widely reported in the literature, and a brief survey of these results is contained in Belytschko et al [17]. Values of are typically in the range of about 1}100 GN/m, depending on rock type, discontinuity roughness, weathering, and other factors.…”

“…Taking the logarithm of Equation (17) shows that k is linearly related to the logarithm of specimen length. Hence, Figure 9(a) can be qualitatively compared to the response shown in Figures 6(b) and 7, where the agreement is seen to be very good.…”

Particle Model for Quasibrittle Fracture and Application to Sea Ice

“…The discrete elernent method was also used by Belytschko et al (1984), Dowding et a1. (1991) and Plesha et al (19?1) for the rnodeling of dilatant slip in rock joints.…”

Mixed time integration for the transient analysis of jointed media

“…The explicit stress increment is computed such that the total stress increment, equation (12), satisfies the constraints given by equations (8) and (10). Thus, the internal force due to deformation at time mAt is given by r Because of the linear relationship between da' and dg, the above can be equivalently written as (16) will be found to be convenient for computing f:.…”