Influences of strain softening and seepage on elastic and plastic solutions of circular openings in nonlinear rock masses

Abstract

Considering the influence of strain softening, the solutions of stress, displacement, plastic softening region radius and plastic residual region radius were derived for circular openings in nonlinear rock masses subjected to seepage. The radial stress distribution curve, ground reaction curve, and relation curve between plastic softening region radius and supporting force in three different conditions were drawn respectively. From the comparisons among these results for different conditions, it is found that when the supporting force is the same, the displacement of tunnel wall considering both seepage and strain softening is 85.71% greater than that only considering seepage. The increase values of radial displacement at 0.95 m and plastic softening region radius at 6.6 m show that the seepage and strain softening have the most unfavorable effects on circular opening stability in strain softening rock masses.

Keywords

strain softening / seepage / nonlinear yield / ground reaction curve / rock masses

References

[1] AlkanH.. Percolation model for dilatancy-induced permeability of the excavation damaged zone in rock salt [J]. International Journal of Rock Mechanics and Mining Sciences, 2009, 46(4): 716-724

[2] ConteE., CosentiniR. M., TronconeA.. Shear and dilatational wave velocities for unsaturated soils [J]. Soil Dynamics and Earthquake Engineering, 2009, 29(6): 946-952

[3] EggerP.. Design and construction aspects of deep tunnels with particular emphasis on strain softening rocks [J]. Tunnelling and Underground Space Technology, 2008, 23(4): 403-408

[4] PanY. S., WangX. B., LiZ. H.. Analysis of the strain softening size effect for rock specimens based on shear strain gradient plasticity theory [J]. International Journal of Rock Mechanics and Mining Sciences, 2002, 39(6): 801-805

[5] AlonsoE., AlejanoL. R., VarasF., Fdez-ManinG., Carranza-TorresC.. Ground response curves for rock masses exhibiting strain softening behavior [J]. International Journal for Numerical and Analytical Methods in Geomechanics, 2003, 27(13): 1153-1185

[6] CorthesyR., LeiteM. H.. A strain-softening numerical model of core discing and damage [J]. International Journal of Rock Mechanics and Mining Sciences, 2008, 45(3): 329-350

[7] VarasF., AlonsoE., AlejanoL., Fdez-maninG.. Study of bifurcation in the problem of unloading a circular excavation in a strain-softening material [J]. Tunnelling and Underground Space Technology, 2005, 20(4): 311-322

[8] HOEK E, CARRANZA-TORRES C, CORKUM B. Hoek-Brown failure criterion — 2002 edition [C]// Proceedings of the North American Rock Mechanics Society Meeting. Toronto, 2002: 267–273.

[9] YangX.-l., HuangFu.. Slope stability analysis considering joined influences of nonlinearity and dilation [J]. Journal of Central South University of Technology, 2009, 16(2): 292-296

[10] CaiM., KaiserP. K., TasakaY., MinamiM.. Determination of residual strength of jointed rock masses using the GSI system [J]. International Journal of Rock Mechanics and Mining Sciences, 2007, 44(2): 247-265

[11] CaiM.. Influence of intermediate principal stress on rock fracturing and strength near excavation boundaries-Insight from numerical modeling [J]. International Journal of Rock Mechanics and Mining Sciences, 2008, 45(5): 763-772

[12] YangX.-li.. Seismic bearing capacity of a strip footing on rock slopes [J]. Canadian Geotechnical Journal, 2009, 46(8): 943-954

[13] YangX.-li.. Seismic displacement of rock slopes with nonlinear Hoek-Brown failure criterion [J]. International Journal of Rock Mechanics and Mining Sciences, 2007, 44(6): 948-953

[14] BakerR.. Inter-relations between experimental and computational aspects of slope stability analysis [J]. International Journal for Numerical and Analytical Methods in Geomechanics, 2003, 27(5): 379-401

[15] CaiM.-f., HeM.-c., LiuD.-yan.Rock mechanics and engineering [M], 2006, Beijing, Science Press: 307-326

[16] RongC.-x., ChengH.. Stability analysis of rocks around tunnel with ground water permeation [J]. Chinese Journal of Rock Mechanics and Engineering, 2004, 23(5): 741-744

[17] LiZ.-l., RenQ.-w., WangY.-hong.. Elasto-plastic analytical solution of deep-circle tunnel considering fluid flow field [J]. Chinese Journal of Rock Mechanics and Engineering, 2004, 23(8): 1291-1295

[18] HoekE., BrownE. T.. Empirical strength criterion for rock masses [J]. Journal of Geotechnical Engineering Division, ASCE, 1980, 106(9): 1013-1035

[19] BrownE. T., BrayJ. W., LadanyiB., HoekE.. Ground response curves for rock tunnels [J]. Journal of Geotechnical Engineering, 1983, 109(1): 15-39

[20] WangY.. Ground response of circular tunnel in poorly consolidated rock [J]. Journal of Geotechnical and Geoenvironmental Engineering, 1996, 122(9): 703-708

[21] YangX.-l., YinJ.-hua.. Slope stability analysis with nonlinear failure criterion [J]. Journal of Engineering Mechanics, 2004, 130(3): 267-273