Swelling rock in tunnels: characterization and effect of horizontal stresses

227A 934160 Study on one-dimensional consolidation of layered systems Lee, P K K; Xie, K H; Cheung, Y K Int J Num Anal Metb Geomech V16, Nil, Nov 1992, P815831 A general solution is presented for the one dimensional consolidation of layered systems, which is more explicit and less computationally tedious than that of Schiffmann and Stein (1970). The relevant computer program has been developed and examples of its output are illustrated. Effects of the coefficients of volume compressibility and permeability are shown to be different and cannot be embodied in the coefficient of consolidation of the soil. The stiffness of the soil layers has significant effect on rate of consolidation.

934161 Laplace-transform-based three-dimensional BEM for pore,flasticity Badmus, T; Cheng, H D; Grilli, S Int J Num Meth Engng V36, N1, Jan 1993, P67-85 A three dimensional boundary element approach to the Biot theory of poroelasticity is presented. The integral transform technique is adopted to avoid the need for time stepping and volume integration, and the solution is found in Laplace transform space. Solution time is obtained via numerical inversion. Moving boundaries and nonlinear governing equations cannot be handled. Several illustrative examples are given, including settlement of a rectangular footing and a modified Mandel problem.

934162 Structural stiffness influence on soil consolidation. Technical note Masih, R J Geotech Engng Div ASCE VII9, N1, Jan 1993, P168-172 The effect on soil consolidation of stiffness of a structure consisting of a regular array of columns with individual footings and connected by beams is examined. Effects of settlement due to consolidation of a cohesive soil on the structure and effects of change of structure forces on the consolidation process are analysed. Direct pressure from foundation to soil and pressure spread according to the Boussinesq equation from one foundation to another are taken into account.

934164

Swelling rock in tunnels: characterization and effect of horizontal stresses Steiner, W Proc ISRM Symposium: Eurock'92, Chester, 14-17 September 1992 P163-168. Publ London: Thomas Telford, 1992 Case histories from tunnels in clay shales and anhydritic shales are presented. Laboratory data on swelling pressures of the materials concerned are compared to those from the field and wide discrepancies seen. Stress paths in the tunnelling are investigated and it is suggested they are not reproduced by the oedometer test. Stress path triaxial tests with pore pressure measurement are recommended for laboratory evaluation of swelling rocks for tunnel design purposes. The importance of in situ horizontal stress to design is noted. Ranges of swelling pressures expected in clay shales and anhydritic shales are given. 934165 Expansive soils in engineering practice Rao, R R Proc Ninth Asian Regional Conference on Soil Mechanics and Foundation Engineering, Bangkok, 9-13 December 1991 V1, P155-158. Publ Thailand: Southeast Asian Geotechnical Society, 1991 A brief summary is presented of a research program at Anchra University, India, to characterise expansive clays relative to their use as foundations for light structures. Identification of expansive soils, theory of heave prediction, measurement of swelling pressure, design swelling pressure, preventive measures against heave, and tolerable heave levels are considered. 934166 One-dimensional settlement analysis for embankments Stauffer, P A; Davidson, R R; Ladd, R S; Paul, D B Proc Conference Stabi~ty and Performance of Slopes and Embankments I1, Berkeley, 29 June-1 July 1992 V1, P387403. Publ New York: ASCE, 1992 (ASCE Special Geotechnical Publication No 31) A simple one dimensional analysis is presented to predict internal settlements and settlements at intermediate construction stages for embankments in clay materials. It is based on conventional compression strain relations and material properties from oedometer tests. Effects of wetting pressures can be taken into account. It is illustrated for the case of the New Wadd¢ll Dam clay core-rockfill shell embankment, and results compared to those of finite element analysis. Laboratory tests evaluated material properties at three typical compaction energies for use in these analyses.

Dynamic properties 934163 Fully coupled model for water flow and air flow in deformable porous media Schrefler, B A; Zhan, X Water Resour Res 1/29, N1, Jan 1993, P155-167 A fully coupled model is presented for simulation of consolidation of a porous medium involving flow of air and water. It is based on Biot theory and incorporates the capillary pressure relation. The governing partial differential equations are solved by the finite element method. Temporal discretization error, iteration error, and stability error are examined. The model is validated against documented experimental data. Applications to air storage in an aquifer and settlement of a flexible footing are shown.

See also: 934201, 934479 934167 Stiffness and strength changes in cohesionless soils due to disturbance Thomann, T G; Hryciw, R Can Geotech J 1/29, N5, Oct 1992, P853-861 A program of laboratory and field investigations is described. Laboratory samples of Ottawa sand were tested in a resonant column torsional shear apparatus before and after high amplitude shear straining. Loss in stiffness and time to regain stiffness are primarily functions of amplitude of the imposed shear strain. In the field, properties of a partially saturated medium dense sand deposit were examined before and after detonation

© 1993 Pergamon Press Ltd. Reproduction not permitted