Effects of longitudinal axial stress and rock mass dilation in analysis of circular tunnels

Effects of longitudinal axial stress and rock mass dilation in analysis of circular tunnels

131A existence of a stationary (asymptotic) stress field for this problem is considered. A worked example of the case of a circular/spherical opening ...

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131A existence of a stationary (asymptotic) stress field for this problem is considered. A worked example of the case of a circular/spherical opening is presented, with results in graphical form. 932458 Calculation of stress and strain state around the working face in heterogeneous rock mass Beksler, Y A; Becbulatov, T A; Chesnokov, S A Proc 7th I S R M International Congress on Rock Mechanics, Aachen, 16-20 September 1991 V1, P679-681. Publ Rotterdam: A A Balkema, 1991

Gasburst and rockburst events in underground mines can be better controlled with knowledge of the stress and strain conditions around the working face. Results of a three dimensional finite element analysis of the elastic problem around an idealised face in a coal seam are illustrated. Effects of heterogeneity of the rock mass, the non-hydrostatic state of the initial stress field, and change of seam thickness on the distribution of tensile and compressive stresses are discussed. 932459 Stresses in the rock during strained solid mass blasting Ermekov, T M; Kayupov, M A; Abuov, M G; Bekbaev, S M; Shaskin, V N Proc 7th I S R M International Congress on Rock Mechanics, Aachen, 16-20 September 1991 V1, P721-725. Publ Rotterdam: A A Balkema, 1991 Once certain stress levels are reached in underground mines, stored energy in the rock is such that it may fail spontaneously, for example by spalling, rockburst, or cutter roof. Study at the Dzezkazgham copper deposits, mined by a caving method, show that rock breaking is most active during and immediately after the blast, and that about 75% of rock which falls does so in this period. Geophysical examination of the rock in the roof shows a weakened zone, damaged by the previous blast, under tensile stress as a result of the 3D stress state in the surrounding rock mass. This tensile stress contributes significantly to the ease with which the roof caves. 932460 Massive stress state around the working being intersected at diameter by the border of the interface of the rock with different deformation characteristics Fotieva, N N; Afanasova, O V Proc 7th I S R M International Congress on Rock Mechanics, Aachen, 16-20 September 1991 111, P725-728. Publ Rotterdam: A A Balkema, 1991

An analytical solution is presented for the stress distribution around a circular tunnel intersected by a plane, passing through the centre of the circle and separating regions of different mechanical properties. Regions of plastic deformation are determined. Results are compared to those for the homogeneous medium case.

method of back analysis is proposed to estimate elastic properties and initial applied stresses. Numerical examples are presented. The procedure is accurate and economical. 932462 Accuracy of identification method for Rnlsotropic mechanical constants of rock mass by local iterated Kalman filter Kadota, S; Saito, E; Koga, S Proc 7th I S R M International Congress on Rock Mechanics, Aachen, 16-20 September 1991 V1, P747-750. Publ Rotterdam: A A Balkema, 1991

Back analyses are used to estimate mechanical constants and initial stress conditions in a rock mass on the basis of measured data. An example is presented where the rock mass is considered an anisotropic elastic continuum. A local iterated extended Kalman filter combined with a global iterated extended Kalman filter is applied to the parameter identification process in order to consider the probabilistic nature of the measured data. The method is accurate enough for practical use,

932463 Effects of longitudinal axial stress and rock mass dilation in analysis of circular tunnels Pan, X D; Reed, M B Proc 7th I S R M International Congress on Rock Mechanics, Aachen, 16-20 September 1991 V1, P785-791. Publ Rotterdam: A A Balkema, 1991 Analysis of the axisymmetric circular tunnel in a homogeneous, isotropic rock under a hydrostatic stress field is presented. Attention is focused on the longitudinal axial stress (out of plane stress) which is not correctly evaluated in many elastoplastic plane strain solutions. Concepts of the analysis and the finite element code used (FESTER) are outlined. Relations between rock mass dilations, tunnel displacements, and in situ stress field are studied. 932464 Effect of internal gas generation on the extension of preexisting fractures around WIPP disposal rooms Arguello, J G; Weatherby, J R; Stone, C M; Mendenhall, F T Proc 33rd US Symposium on Rock Mec&mics, Santa Fe, 3-5 June 1992 P399-408. Publ Rotterdam: A A Balkema, 1992 Significant volumes of gas are expected as a result of corrosion and microbial degradation of waste and waste packages during the life of the WIPP. Pressure inside a room could increase slowly with time, retarding closure and reducing the final degree of compaction of the waste, or create fractures in the rock salt host, providing potential leakage paths. The finite element code SANCHO is used to investigate the effects of internal gas generation on the extension of pre-existing fractures and to assess the condition of the room at any given time.

Underground excavation failure mechanisms 932461 Quasi 3-D back analysis of tunnel in anisotropic rock Hirashima, K; Kawakami, T; Fujiwara, T; Yamashita, Y Proc 7th I S R M International Congress on Rock Mechanics, Aachen, 16-20 September 1991 V1, P733-736. Publ Rotterdam: A A Balkema, 1991

932465 Estimation of critical convergence and rock load in coal mine roadways - an approach based on rock mass rating Ghosh, C N; Ghose, A K Int J Geotech Geol Engng VIO, N3, Sept 1992, P185-202

A procedure for the quasi three dimensional analysis and back analysis for tunnel excavation in isotropic or anisotropic rock masses is presented. As the first stage, exact solutions of elasticity for circular,elliptical, and arbitrarily shaped excavations are used to obtain stresses and displacements for in-plane and out-of-plane loadings. On the basis of this formulation, a

Ground movements create major safety hazards in Indian coal mines. 8 bord and pillar mines, representing a range of depths and strata conditions, were instrumented and support pressures and convergence monitored. Several roofs were allowed to fail in order to allow development of predictive equations for roof falls. An empirical relation for safe roof load has been

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