126A

844029 Rock engineering studies with reference to the in-situ strength of bauxite pillars Passaris, E K S In: Strata Mechanics (paper to the Symposium on Strata Mechanics, Newcastle upon Tyne, 5-7 April 1982) P278-282. Publ Amsterdam." Elsevier, 1982

An empirical approach is employed for the determination of the in-situ strength of bauxite pillars. The work is based on data ob- tained from a survey of actual mining conditions carried out in panel 790 of the '51KM' bauxite mine in Greece. In order to arrive at an estimate of the average pillar stress, use was made of an improved formula which takes into account several rock engineering factors otherwise ignored by the classic tributary area theory. A comparison of the actual data with the estimated values indicated that the method used in this paper is a satisfac- tory approach in predicting the strength of bauxite pillars.

844O3O Set-up for determining shear behaviour of joints in model materials Cruz Azevedo, M; Esteves Ferreira, M J Laboratorio Nacional de Engenhariu Civil memoria N596, 1983, 23P

A test rig is described, designed for determining the laws of shear behaviour of joints between blocks of a geomechanical model material. It is aimed at assessing how shear stresses and normal displacements depend on the constant normal stresses and the shear horizontal displacements imposed during the tests.

844031 Centrifugal test for the tensile strength of rock Wijk, G Swedish Detomc Research Fonadation report DS 1984:1, 20 Feb 1984, 7P

The uniaxial tensile strengths of Bohus granite, Ekeberg marble and Lemunda sandstone were determined by a direct tensile testing method. The results from this method - spinning a rock core and measuring the angular velocity at which it is torn off at the middle due to the centrifugal tension - compare well with tensile strength data from conventional tests.

Avail: Swedish Detonic Research Foundation, Box 32058, S- 126 11 Stockholm, Sweden

Deformation characteristics

See also: 844056

844032 Apparatus for cyclic stress l~th testing Khosla, V K; Singh, R D Geoteck Test J V6, N4, Dec 1983, P165-172

A modification to the conventional cyclic triaxial cell was made to carry out mean stress tests on dense dry Ottawa sand. Limited test results show that stress-strain characteristics under cyclic loading conditions are significantly affected by the imposed stress path.

844O33 Density variation in l m ~ y # i~ i¢ flow of granular media Drescher, A; Michalowski, R L Gcotcclmiqu¢ V34, N1, March 1984, PI-IO

Examines the variation of density of granular media treated as rigid-perfectly plastic solids, in some cases of quasi-static, pseudo-steady plane deformation. The kinematic solutions dis-

cussed are characterized by dilation occurring exclusively across velocity discontinuity lines. The solution suggested by Drescher, Cousens and Bransby is used to study the flow of granular material through a hopper. It is shown that in the ra- dial flow zone the density distribution is non-uniform. A second problem, the indentation of a wedge into a ponderable half space is also considered; it is found that regions of different density do exist.

844O34 Reaction of clays to sam#ing stress relief Kirkpatrick, W M; Khan, A J Geotechnique V34, N1, March 1984. P29-42

Describes investigations into the influence of stress relief caused by sampling on the undrained stress-strain behaviour of nor- mally consolidated clays. The work was performed on laboratory manufactured kaolin and illite; in situ and sample conditions were simulated. Physical disturbance effects were cut to a minimum. Undrained triaxial compression tests were used. Results indicate that the consolidated undrained test is mis- leading for predicting in situ undrained behaviour where stress relief is appreciable. It is found that the in situ behaviour of young, relatively insensitive clays can be reproduced with reasonable accuracy from samples reconsolidated to the in situ stresses.

844035 Plasticity theory for fluid ~torated porous solids de Boer, R; Kowalski, S J Int J Engng Sci V21, Ni l , 1983, P1343-1357

A theory of plastic flow is developed for an elastic-perfectly plastic porous solid with its interconnecting void spaces filled with a viscous fluid. The constitutive equations are established using thermodynamic equations. The final result of the paper is the complete set of equations of the theory and the boundary conditions for the medium in question. Auth.

844036 Rigid indmioas in GrilBth cracks in a granular solid Lal, M lnt J Engng Sci V22, N2, 1984, P175-185

The effect of rigid inclusions on the stress concentration around a Griffith crack under plane strain is examined using Weiskopfs theory of granular solids and Fourier transform techniques.

844O37 On the viscocl~tt¢ bclUviour of a Imroas saturated medium Ene, H I; Melicescu-Receanu, M int J Engng Sci V22, N3, 1984, P243-246

Presents an example of a macroscopic constitutive equation ob- tained from microscopic known equations for the case of a mix- ture formed by a viscoelastic solid and a viscous fluid.

844038 Rapid expansion of a cylindrical cavity in a rate-type soil Davis, R O; Scott, R F; Mullenger, G Int J Num Asal Moth Geomech VS, N2, March-April 1984, P125-140

An analytical solution for rapid (undrained) expansion of a long cylindrical cavity from initially zero radius is presented. A sim- ple rate-type soil model possessing the salient features of the modified Cambridge critical state model is used. Application of the solution to the determination of the stress field surrounding a pile immediately after driving is discussed. Auth.