A displacement-based back-analysis method for rock mass modulus and horizontal in situ stress in tunneling – Illustrated with a case study

Zhang, L.Q.; Yue, Zhen; Yang, Zhuangzhi; Qi, Jingjing; Liu, F.C.

doi:10.1016/j.tust.2005.12.001

Cited by 89 publications

(30 citation statements)

References 10 publications

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“…In numerical simulations, the in situ stress fields are generally acquired by a number of methods using limited measurement and topography data used for design and construction at various engineering sites (Zhang et al, 2006;Guo et al, 2008;Qin et al, 2008). These methods include multiple linear regression (MLR) analysis, artificial neural network (ANN) methods (Kartam et al, 1997;Xu, 2000;Li et al, 2012;Samui et al, 2015), and genetic algorithm optimization approaches, which have been adopted extensively within stress boundary conditions and displacement boundary conditions in particular.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional inversion analysis of an in situ stress field based on a two-stage optimization algorithm

Zhang

Chao

2016

J. Zhejiang Univ. Sci. A

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Abstract:Establishing an accurate in situ stress field is important for analyzing the rock-mass stability of the underground cavern at the Huangdeng hydropower station in China. Because of the complexity and importance of the in situ stress field, existing back analysis methods do not provide the necessary accuracy or sufficiently recognize nonlinear relations between the distribution of the in situ stress field and its formative factors. Those factors are related to the geological structures of high compressive tectonic stress regimes, including geological faults and tuff interlayers. The new two-stage optimization algorithm proposed in this paper is a combination of stepwise regression (SR), difference evolution (DE), support vector machine (SVM), and numerical analysis techniques. Stepwise regression is used to find the set of unknown parameters that best match the modeling prediction and determine the range of parameters to be recognized. Difference evolution is used to determine the optimum parameters of the SVM. The SVM is used to create the DE-SVM nonlinear reflection model to obtain the optimal values of the parameters from measured stress data. We compare the new two-stage optimization algorithm to other two popular methods, a multiple linear regression (MLR) analysis method and an artificial neural network (ANN) method, to estimate the in situ stress field for the actual underground cavern at the Huangdeng hydropower station. The two-stage optimization algorithm produces a more realistic estimate of the stress distribution within the investigated area. Thus, this technique may have practical applications in realistic scenarios requiring efficient and accurate estimations of the in situ stress in a rock-mass.

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Section: Introductionmentioning

confidence: 99%

Three-dimensional inversion analysis of an in situ stress field based on a two-stage optimization algorithm

Zhang

Chao

2016

J. Zhejiang Univ. Sci. A

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“…For some purposes, large-scale eld monitoring work must be conducted before large-scale engineering projects are begun. This work may include the use of hydraulic fracturing tests and borehole stress-relief tests to measure in-situ stresses [3]. There are currently plans to build a large number of hydropower stations in southwestern parts of China, most of which will be located in deep, narrow valleys.…”

Section: Introductionmentioning

confidence: 99%

A modified initial in-situ Stress Inversion Method based onFLAC3D with an engineering application

Guo

Zhu

et al. 2015

Open Geosciences

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Abstract:To improve the accuracy of an initial in-situ stress eld determined by inversion, we describe a modi ed initial in-situ stress inversion method that uses partial least-squares regression based on FLAC3D. First, each stress component is regressed to improve the tting accuracy of locally abnormal stress regions, and then the relationship between element stress and unbalanced node force is analyzed according to the computational principles of FLAC3D. The initial in-situ stresses obtained from these regression calculations are added to a numerical model, and the unbalanced node forces are recalculated. An external force equal to the recalculated unbalanced node force is then exerted on the node in the direction opposing the original unbalanced node force to satisfy the equilibrium condition. For the in-situ stresses of elements that do not satisfy the strength conditions, they are modi ed by assuming the average stress is constant and reducing the partial stress to satisfy the equilibrium and strength conditions, which also resolves the unreasonable distribution of the boundary nodal forces and results in good regression estimates. A three-dimensional hypersurface spline interpolation method is developed to calculate the in-situ stress tensor at arbitrary coordinates. Finally, we apply this method to an underground engineering project, and the results are shown to agree well with those obtained from eld monitoring. Therefore, it is concluded that this modi ed in-situ stress inversion method could e ectively improve the tting accuracy of locally abnormal stress regions.

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“…2) Due to the influences of joints or fissures, hydraulic fracturing tests and borehole stress-relief tests are often costly and time-consuming with dispersive data covering small test domain [15].…”

Section: Introductionmentioning

confidence: 99%

“…could be provided, all the unknowns would be determined analytically or numerically. In the rock engineering, the identification based upon the measured displacement is often used to determine classical elastic constitutive parameters or/and insuit stress of rock mass [14,15,16,17,18,19,20,21,22]. In comparison with the previous work based on the classical elasticity, the parameters identification of the inverse couple stress problem includes both constitutive parameters appearing in the classical model and those additional items describing the constitutive relationship of couple stress.…”

Section: Introductionmentioning

confidence: 99%

“…Since the displacement that is usually reliable and is easily measured [15], this paper suggests exploiting the displacements of rock masses induced by excavation to determine the unknown constitutive parameters and in-situ stress for the layered rock mass formulated by Cosserat theory. We propose a numerical model that consists of two parts, one is for the description of direct problem formulated by FEM, two key issues in this part include the effect of excavation and implementation of sensitivity analysis; Another one is for the description of inverses problem that is treated as an optimization problem solved by the Gauss-Newton technique, the major issues concerned in this part include the combined identification, regional in-homogeneity, and computing accuracy with the consideration of noisy 'measurement' message.…”

Section: Introductionmentioning

confidence: 99%

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Combined identification of constitutive parameters and in-situ stress in layered rock mass formulated by Cosserat theory

Yang

Wang

2008

J. Phys.: Conf. Ser.

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Abstract. This paper focuses on the identification of constitutive parameters and in-situ (initial) stress in the layered rock mass formulated by Cosserat theory. The direct problem is modeled by FEM (Finite Element Method), providing a platform at which the sensitivity analysis can be implemented, and the inverse problem is solved via the Gauss-Newton technique. The effects of initial guesses and noisy data on the solutions are investigated, and satisfactory results are exhibited in the numerical verification. IntroductionOccurrence of a stratified (layered) rock mass for a mineral deposit is not uncommon in mining practice and results in highly anisotropic strength and deformation characteristics. This makes it necessary to include effects of joints into the mathematical formulations describing the load-deflection behavior. In addition to the discontinuous modeling method by which the joints in the rock mass and intact rock layers are modeled individually [1,2], another kind of modeling method is the continuum one by which the whole layered rock mass with joints is represented by an equivalent continuum model providing a reasonable large scale (average) description of the material response to loading especially when closely spaced joints occur in large numbers [3,4], and make the discontinuous modeling impossible.One of the effective equivalent continuum models is that based on the couple stress theory (Cosserat theory). In a mechanical point of view, Reference[5] and its cited papers illustrated the justification for the use of the Cosserat theory in layered rock mass, and provided numerical evidence that the Cosserat model is capable of accurately reproducing complex load-deformation patterns via a comparison with calculations conducted using the discrete joint model.The couple stress theory (Cosserat theory) can be traced back to 1887 when Voigt assumed the existence of couple stress. In 1909, the Cosserat brothers first set up a framework of couple stress theory which has been further developed by [6,7,8]. Zvolinskii and Shkhinek [9] applied the Cosserat theory to formulate a model of layered material with elastic coupling between the layers and later Bogan [10] confirmed the mathematical viability of this model. Extensive development of the Cosserat theory in relation to layered rock mass has been carried out by Mühlhaus [11], Adhikary and A.V. Dyskin [5,12,13].The study of this paper is motivated by a question that if a continuum couple stress theory is adopted for modeling the layered rock mass, how to determine those equivalent constitutive

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A displacement-based back-analysis method for rock mass modulus and horizontal in situ stress in tunneling – Illustrated with a case study

Cited by 89 publications

References 10 publications

Three-dimensional inversion analysis of an in situ stress field based on a two-stage optimization algorithm

Three-dimensional inversion analysis of an in situ stress field based on a two-stage optimization algorithm

A modified initial in-situ Stress Inversion Method based onFLAC3D with an engineering application

Combined identification of constitutive parameters and in-situ stress in layered rock mass formulated by Cosserat theory

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