Parametric modeling on spatial effect of excavation-damaged zone of underground cavern

Abstract

Regarding excavation-damaged zone (EDZ) around underground opening as non-homogeneous rockmass with spatial deterioration effect on stuffiness and strength, a parametric model of EDZ using radius-displacement-dependent deformation modulus (RDDM) was proposed. Considering the nonlinearity characteristic of deformation and locality otherness of surrounding rock, deterioration parameter field of deformation modulus of rockmass around opening was quantitatively calculated through a given function. Applicability for multi-cavern condition and parameter sensibility of the model was analyzed by numerical experiments using synthetic data. Furthermore, the model was applied to identify EDZ of underground caverns of Pubugou hydropower station by calculating deterioration parameter field. Based on the parametric analysis of spatial effect and geological investigation, it is recognized that large radial deformation of deep fractured rock at the spandrel position and insufficient supporting bolts mainly result in great deformation pressure to act on the shotcrete and cause partial crack and spalling. It is shown that deterioration parameter field along the longitudinal axis of main powerhouse is evidently non-homogeneous in space and distributes exponentially along the radius from the opening. The model provides a simple and convenient way to identify the EDZ in the working state for rapid construction feedback analysis and support optimization of underground cavern from quantitative point of view and also aids in interpreting monitoring displacements and estimating support requirements.

Keywords

underground cavern / excavation-damaged zone / spatial effect / parametric modeling / deformation modulus

References

[1] ReadR S. 20 years of excavation response studies at AECL’s underground research laboratory [J]. International Journal of Rock Mechanics and Mining Sciences, 2004, 41(8): 1251-1275

[2] KwonS, LeeC S, ChoS J, JeonS W, ChoW J. An investigation of the excavation damaged zone at the KAERI underground research tunnel [J]. Tunnelling and Underground Space Technology, 2009, 24(1): 1-13

[3] MartinoJ B, ChandlerN A. Excavation-induced damage studies at the underground research laboratory [J]. International Journal of Rock Mechanics and Mining Sciences, 2004, 41(8): 1413-1426

[4] ChangS-h, LeeC-i, LeeY-kyou. An experimental damage model and its application to the evaluation of the excavation damage zone [J]. Rock Mechanics & Rock Engineering, 2007, 40(3): 245-285

[5] NawrockiP A, DusseaultM B. Modelling of damaged zones around openings using radius-dependent elastic modulus [J]. Rock Mechanics & Rock Engineering, 1995, 28(4): 227-239

[6] SaiangD. Stability analysis of the blast-induced damage zone by continuum and coupled continuum-discontinuum methods [J]. Engineering Geology, 2010, 116(1/2): 1-11

[7] GolshaniA, OdaM, OkuiY, TakemuraT, MunkhtogooE. Numerical simulation of the excavation damaged zone around an opening in brittle rock [J]. International Journal of Rock Mechanics and Mining Sciences., 2007, 44(6): 835-845

[8] MaejimaT, MoriokaH, MoriT. Evaluation of loosened zones on excavation of a large underground rock cavern and application of observational construction techniques [J]. Tunnelling and Underground Space Technology, 2003, 18(2): 223-232

[9] YeZ-y, HongL, LiuX-l, YinT-bing. Constitutive model of rock based on microstructures simulation [J]. Journal of Central South University of Technology, 2008, 15(2): 230-236

[10] ZhangP, LiX-b, LiNing. Strength evolution law of cracked rock based on localized progressive damage model [J]. Journal of Central South University of Technology, 2008, 15(4): 493-497

[11] HoekE, DiederichsM S. Empirical estimation of rock mass modulus [J]. International Journal of Rock Mechanics and Mining Sciences, 2006, 43(6): 203-215

[12] LuW-b, LiP, ChenM, ZhouC-b, ShuD-qiang. Comparison of vibrations induced by excavation of deep-buried cavern and open pit with method of bench blasting [J]. Journal of Central South University of Technology, 2011, 18(5): 1709-1718

[13] JiangS-p, CaiZ-w, LinZ, LiX-p, ZhangC-liang. Kalman filtering & FEM coupling back analysis method considering broken zone and its application to stability analysis of surrounding rock [J]. Rock and Soil Mechanics, 2009, 30(8): 2529-2534

[14] LiS-j, YuH, LiuY-x, WuF-ji. Results from in-situ monitoring of displacement, bolt load, and disturbed zone of a powerhouse cavern during excavation process [J]. International Journal of Rock Mechanics and Mining Sciences, 2008, 45(8): 1519-1525

[15] LiN, DuanX-q, ChenF-f, YuanJ-guo. A back analysis method for elastoplastic displacement of broken rock zone around tunnel [J]. Chinese Journal of Rock mechanics and Engineering, 2006, 25(7): 1304-1308

[16] KulhawyF H. Stress deformation properties of rock and rock discontinuities [J]. Engineering Geology, 1975, 9: 327-350

[17] Müller, LiS-p, FengZ-hTr. Rock mechanics [M], 1981BeijingChina Coal Industry Publishing House13-29

[18] ZhangZ-g, XiaoMing. Inversion of monitored displacement field and evaluation of surrounding rock stability of underground caverns [J]. Chinese Journal of Rock Mechanics and Engineering, 2009, 28(4): 813-818

[19] YuY-t, XiaoMing. Three dimensions elasto-plastic finite element analysis for the surrounding rock stability of large-scale underground openings [J]. Chinese Journal of Rock mechanics and Engineering, 1987, 6(1): 47-56

[20] ZhuW-s, ZhouK, YuD-j, WangL-g, MaQ-song. Study of field monitoring and damage mechanics analysis of brittle fractured rock masses [J]. Chinese Journal of Rock Mechanics and Engineering, 2010, 29(10): 1963-1969