Stiffness Of Rock Mass Research Articles

Practical equivalent continuum characterization of jointed rock masses

A simple practical method to characterize the strength and stiffness of jointed rock masses is presented in this paper. The empirical relations for the strength and stiffness of rock masses have been arrived based on the statistical analysis of a large amount of experimental data, which are used for representing the jointed rock mass as an equivalent continuum. The effect of joints in the rock mass is taken into account by a joint factor. These obtained relations are incorporated in a non-linear FEM code to represent the equivalent continuum analysis. The equivalent continuum model has been validated against experimental results for jointed rock masses with different joint fabric and joint orientation and also with the results from explicit modeling of joints using FEM. The developed model has also been applied to calculate the deformation around a large power station cavern in rhyolite rock at 200 m depth.

In situ evaluation of rock mass stiffness variations for underground openings using surface wave and borehole seismic methods : Nelson, P P; Lopez, M; Stokoe, K H; Roblee, C J Proc 7th Annual Workshop Generic Mineral Technology Center Mine System Design and Ground Control, Blacksburg, 22–24 October 1989P35–46. Publ Blacksburg: Virginia Polytechnic Institute and State University, 1989

In situ evaluation of rock mass stiffness variations for underground openings using surface wave and borehole seismic methods : Nelson, P P; Lopez, M; Stokoe, K H; Roblee, C J Proc 7th Annual Workshop Generic Mineral Technology Center Mine System Design and Ground Control, Blacksburg, 22–24 October 1989P35–46. Publ Blacksburg: Virginia Polytechnic Institute and State University, 1989

Monitoring the Bowen Bridge foundations : Chandler, B C; Harvey, R J Proc 4th Australia-New Zealand Conference on Geomechanics, Perth, Western Australia, 14–18 May 1984 V2, P427–432. Publ Barton: Inst of Engineers, 1984

Bowen Bridge is the second road crossing of the Derwent River in Hobart. In addition to superstructure loading the bridge piers have been designed to withstand impact from 5000 tonne barges, this design feature being introduced principally as a result of the Tasman Bridge disaster in January, 1975. The bridge is supported on 13.3m diameter caissons, extending to 47m below river level to found on rock. This paper presents details of site stratigraphy, design and general arrangement of the foundations. Monitoring of two aspects of rock performance during construction is included in the paper; water pressure relief for cofferdam dewatering and rock mass stiffness for comparison with design assumptions. Water pressure relief in the rock at and below foundation level was required to permit construction of the caisson walls in the dry inside cofferdams. Pressure relief holes were drilled in the rock and piezometers installed to monitor pressures during and after dewatering. Rock mass stiffness is a significant parameter in assessing the response of the foundation to superstructure and ship impact loadings. A programme of rock coring and pressuremeter testing provided estimates of rock stiffness for design purposes. These estimates are compared with data from direct reading multi-rod extensometers installed up to 60m below river level. Details of the extensometer installations, together with assessments of rock mass stiffness from pressuremeter and extensometer records are presented (Author/TRRL)

Side resistance rock sockets in sandstone, mudstone, and shale

The fundamental parameters of rock strength, rock mass stiffness, and interface roughness that control the development of side shear in a rock socketed pile are discussed on the basis of results from laboratory model socket tests, constant stiffness direct shear tests, and instrumented prototype piles. Based on the understanding of these fundamental parameters and on a survey of socket field test results, an empirical design method is proposed for side shear only sockets. This design method considers both the maximum load capacity and settlement criteria for single sockets.

Scale effects in the determination of rock mass strength and deformability

Scale Effects in the Determination of Rock Mass Strength and Deformability An extensive literature search was conducted, to investigate the effect of the scale of testing on the measurement of strength and stiffness of rock masses. The results are presented for bearing capacity tests, compression tests, and several types of deformability tests. Field strength values are generally several times smaller than laboratory values. Field moduli generally appear to be between 20 per cent to 60 per cent of laboratory measured moduli. All strength and deformability results reviewed point to the great need for more field tests. Specific suggestions are given.