Laboratory tests and numerical simulations of brittle marble and squeezing schist at Jinping II hydropower station, China

Zhang, Chunsheng; Chu, Weijiang; Liu, Ning; Zhu, Yongsheng; Hou, Jirui

doi:10.3724/sp.j.1235.2011.00030

Cited by 31 publications

(7 citation statements)

References 15 publications

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“…Brideau et al 2011;Shen et al 2012;Schaefer et al 2013;Dotta et al 2017), tunnel design (e.g. Martin et al 1999;Cai et al 2004;Genis et al 2007;Zhang et al 2011), mining geotechnics (e.g. Alber et al 2009) and more recently in reservoir geomechanics (e.g.…”

Section: Introductionmentioning

confidence: 99%

Estimating in situ rock mass strength and elastic modulus of granite from the Soultz-sous-Forêts geothermal reservoir (France)

et al. 2018

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Knowledge of the strength and elastic modulus of a reservoir rock is important for the optimisation of a particular geothermal resource. The reservoir rock for many geothermal projects in the Upper Rhine Graben, such as those at Soultz-sous-Forêts and Rittershoffen (both France), is porphyritic granite. High fracture densities (up to ~ 30 fractures/m) in this reservoir rock require that we consider the strength and elastic modulus of the rock mass, rather than the intact rock. Here we use uniaxial and triaxial deformation experiments performed on intact rock coupled with Geological Strength Index assessments-using the wealth of information from core and borehole analyses-to provide rock mass strength and elastic modulus estimates for the granite reservoir at Soultz-sous-Forêts (from a depth of 1400 to 2200 m) using the generalised Hoek-Brown failure criterion. The average uniaxial compressive strength and elastic modulus of the intact granite are 140 MPa (this study) and 40 GPa (data from this study and the literature), respectively. The modelled strength of the intact granite is 360 MPa at a depth of 1400 m and increases to 455 MPa at 2200 m (using our estimate for the empirical m i term of 30, determined using triaxial and tensile strength measurements on the intact granite). Strength of the rock mass varies in accordance with the fracture density and the extent and nature of the fracture infill, reaching lows of ~ 40-50 MPa (in, for example, the densely fractured zones in EPS-1 at depths of ~ 1650 and ~ 2160 m, respectively) and highs of above 400 MPa (in, for example, the largely unfractured zone at a depth of ~ 1940-2040 m). Variations in rock mass elastic modulus are qualitatively similar (values vary from 1 to 2 GPa up to the elastic modulus of the intact rock, 40 GPa). Our study highlights that macrofractures and joints reduce rock mass strength and should be considered when assessing the rock mass for well stability and rock mass deformation due to stress redistribution in the reservoir. We present a case study to demonstrate how a simple and cost-effective engineering method can be used to provide an indication of the in situ strength and elastic modulus of reservoir rock masses, important for a wide range of modelling and stimulation strategies. We recommend that the effect of macrofractures on rock mass strength and stiffness be validated for incorporation into geomechanical characterisation for geothermal reservoirs worldwide.

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Section: Introductionmentioning

confidence: 99%

Estimating in situ rock mass strength and elastic modulus of granite from the Soultz-sous-Forêts geothermal reservoir (France)

et al. 2018

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“…In this study, a Hoek-Brown non-linear peak strength envelope was fitted to the fracture data and a linear envelope to the residual strength data. The same principle for the determination of the brittle-ductile transition was used by other authors including Murrell (1965), Mair et al (2002), Zhang et al (2011) and Zhu et al (2019). Four types of macroscopic mechanical and deformational behavior were observed, as schematically shown in (Fig.…”

Section: Axial Stress-axial Strain Characteristicsmentioning

confidence: 92%

Brittle-Ductile Transition and Hoek–Brown mi Constant of Low-Porosity Carbonate Rocks

2021

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The mechanical behavior of low porosity carbonate rocks is investigated by a series of conventional triaxial compression tests performed at room temperature, at various confining pressures up to 70 MPa and at a constant strain rate of 5 9 10 -5 s -1 . Aiming at an improvement of the accuracy and quality of the constant m i of the non-linear Hoek-Brown criterion for jointed rock, four dense, high strength and low-porosity carbonate rocks were tested in conventional triaxial testing, under confining pressures over the entire brittle field, from r 3 = 0 to the brittleductile transition. Intact, fresh and dry specimens from limestones and two marbles were tested using a standard NX Hoek triaxial cell. The results indicate that the average brittle-ductile transition pressure and the value of m i determined by the experimental data over the entire brittle field, were approximately twice as high for limestones as for marbles. With the inclusion of the results from five well-known carbonate rocks published by other researchers, it was found that, for the total number of nine carbonate rocks, the ratio of the critical principal stress ratio at the transition (r 1 /r 3 ) was equal to 5.84 irrespective of rock type, transition pressure, grain size, and m i value. Moreover, the transition pressure decreases logarithmically with the average rock grain size and the ratio of the transition pressure to the unconfined compressive strength r ci .

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“…Jinping marble is a typical brittle rock, and its mechanical properties have been reported in many studies [31,[37][38][39][40][41][42][43]. In this study, the Jinping marble is used for parameter calibration, and a set of mechanical properties of Jinping marble, including uniaxial compressive strength (UCS), elastic modulus, Poisson's ratio, and tensile strength (TS), are matched with the simulated values [31,43].…”

Section: Calibration Of Micro-parametersmentioning

confidence: 99%

Study on Evolution Mechanism of Structure-Type Rockburst: Insights from Discrete Element Modeling

Zhang

et al. 2021

Sustainability

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Taking the “11.28” rockburst occurred in the Jinping II Hydropower Station as the engineering background, the evolution mechanism of structure-type rockburst was studied in detail based on the particle flow code. The results indicate that the failure mechanism of structure-type rockburst includes a tensile fracture induced by tangential compressive stress and a shear fracture caused by shear stress due to overburdened loadings and shear slip on the structural plane. In addition, it is found that the differences between structure-type rockburst and strainburst mainly include (a) the distribution of the local concentrated stress zone after excavation, (b) the evolution mechanism, and (c) the failure locations. Finally, the influence of four factors on the structure-type rockburst are explored. The results show that (1) when the friction coefficient is greater than 0.5, the effect of structural plane is weakened, and the rock near excavation tends to be intact, the structural-type rockburst intensity decreases; (2) the dissipated and radiated energy in structural-type rockburst reduces with rockmass heterogeneity m; (3) the lateral pressure coefficient has a significant effect on the intensity of deep rock failure, specifically in the form of the rapid growth in dissipative energy; (4) and the structural-type rockburst is more pronounced at a structural plane length near 90 mm.

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Laboratory tests and numerical simulations of brittle marble and squeezing schist at Jinping II hydropower station, China

Cited by 31 publications

References 15 publications

Estimating in situ rock mass strength and elastic modulus of granite from the Soultz-sous-Forêts geothermal reservoir (France)

Estimating in situ rock mass strength and elastic modulus of granite from the Soultz-sous-Forêts geothermal reservoir (France)

Brittle-Ductile Transition and Hoek–Brown mi Constant of Low-Porosity Carbonate Rocks

Study on Evolution Mechanism of Structure-Type Rockburst: Insights from Discrete Element Modeling

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