Elastoplastic Analysis of Circular Openings in Elasto‐Brittle‐Plastic Rock Mass Based on Logarithmic Strain

Zhang, Qiang; Li, Cheng; Min, Ming; Jiang, Binsong; Yu, Liyuan

doi:10.1155/2017/7503912

Cited by 5 publications

(4 citation statements)

References 10 publications

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“…en, the training set is trained to establish a regression model that is used for evaluating the parameters for the random forest regression methods. To determine reasonable and optimized hyperparameters for the random forests, a fivefold CV procedure [20,[36][37][38][39][40][41][42] was implemented to determine the optimal parameter values based on the original training dataset. In addition, the sqrt(x) function was to be utilized to determine each node of the random tree where x is the number of the input variables.…”

Section: Results Of Hyperparameter Tuningmentioning

confidence: 99%

“…eoretical analyses are based mainly on different constitutive models and failure criteria, such as Mohr-Coulomb and Hoek-Brown failure criteria [19], which do not consider the effect of intermediate principal stress on EDZs. e Drucker-Prager criterion and unified strength theory have been used to solve the elasticplastic problem of surrounding rocks in underground roadways [20,21]. In general, the results of theoretical analyses have large gaps compared with results from field tests.…”

Section: Introductionmentioning

confidence: 99%

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Space‐Time Distribution Laws of Tunnel Excavation Damaged Zones (EDZs) in Deep Mines and EDZ Prediction Modeling by Random Forest Regression

Xie

Peng

2019

Advances in Civil Engineering

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The formation process of EDZs (excavation damaged zones) in the roadways of deep underground mines is complex, and this process is affected by blasting disturbances, engineering excavation unloading, and adjustment of field stress. The range of an excavation damaged zone (EDZ) changes as the time and space change. These changes bring more difficulties in analyzing the stability of the surrounding rock in deep engineering and determining a reasonable support scheme. In a layered rock mass, the distribution of EDZs is more difficult to identify. In this study, an ultrasonic velocity detector in the surrounding rock was used to monitor the range of EDZs in a deep roadway which was buried in a layered rock mass with a dip angle of 20–30°. The space-time distribution laws of the range of EDZs during the excavation process of the roadway were analyzed. The monitoring results showed that the formation of an EDZ can be divided into the following stages: (1) the EDZ forms immediately after the roadway excavation, which accounts for approximately 82%–95% of all EDZs. The main factors that affect the EDZ are the blasting load, the excavation unloading, and the stress adjustment; (2) as the roadway excavation continues, the range of the EDZs increases because of the blasting excavation and stress adjustment; (3) the later excavation zone has a comparatively larger EDZ value; and (4) an asymmetric supporting technology is necessary to ensure the stability of roadways buried in layered rocks. Additionally, the predictive capability of random forest modeling is evaluated for estimating the EDZ. The root-mean-square error (RMSE) and mean absolute error (MAE) are used as reliable indicators to validate the model. The results indicate that the random forest model has good prediction capability (RMSE = 0.1613 and MAE = 0.1402).

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Section: Results Of Hyperparameter Tuningmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Space‐Time Distribution Laws of Tunnel Excavation Damaged Zones (EDZs) in Deep Mines and EDZ Prediction Modeling by Random Forest Regression

Xie

Peng

2019

Advances in Civil Engineering

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“…Mo et al [34] described the confinement-convergence responses for deep tunnels in linearly elastic, non-associated MC, and brittle Hoek-Brown rock masses using large-strain solutions of unified spherical and cylindrical cavity contraction. Zhang et al [35] derived a large strain differential equations for elasto-brittle-plastic rock masses and implemented a numerical procedure.…”

Section: Introductionmentioning

confidence: 99%

A New Numerical Finite Strain Procedure for a Circular Tunnel Excavated in Strain-Softening Rock Masses and Its Engineering Application

et al. 2022

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The small strain theory underestimates the self-bearing capacity of rock masses, especially for a soft rock tunnel under high geostress. To perform an efficient and accurate calculation and provide a reference for the stiffness design of a tunnel, the finite strain solution for a circular tunnel in Mohr–Coulomb strain-softening rock masses with a non-associated flow rule was derived as three sets of differential equations under the Lagrangian coordinate, which are in the residue region, the softening region, and the elastic region, respectively. Based on the bisection method, an iteration procedure for solving the finite strain solution was proposed to approximate the boundary condition at infinity, the values of two adjacent boundaries, and the initial values on the excavation boundary. This numerical procedure was verified by comparing with self-similar solutions, recursive solutions, and FLAC simulation results. In the calculation example, the relative error on boundaries can be decreased to less than 10−8 after only 10 times iteration and the time for each calculation is less than 15 s. Applying this procedure on the sensibility analysis and stiffness reliability design for the Zhongyi tunnel, a support stiffness of 4.3 MPa/m is recommended to guarantee a tunnel displacement lower than 0.5 m.

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“…For soft rock mass, the creep displacement is significant with a deformation ratio of tens of millimeters per day. If the supporting intensity is weak, the deformation ratio can reach tens of centimeters per day [2].…”

Section: Introductionmentioning

confidence: 99%

Analytical solution of circular tunnel in elastic-viscoplastic rock mass

Wang

Jiang

Zhang

et al. 2019

Lat. Am. j. solids struct.

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This paper deals with a deep circular tunnel excavated in infinite homogeneous and isotropic elastoviscoplastic rock mass subjected to a hydrostatic initial stresses. The tunnel is divided into the initial plastic, viscoplastic, and elastic zones. By combining the generalized Bingham model with Mohr-Coulomb yield criteria, analytical solutions of the circular tunnel are derived with the consideration of non-associated flow rule and elasto-viscoplasticity. The initial plastic zone is defined as the instantaneous change of rock mass excavation. Based on the initial plastic zone, the stresses in viscoplastic zone are transferred to the deep surrounding rock with time due to the initial earth stresses. The results are compared with the elastic-brittle solution at static conditions, and the solutions of this paper are validated. Moreover, the presented results shows that the stress and displacement of the surrounding rock varies with time, and the solutions can be obtained at different instants of time.

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Elastoplastic Analysis of Circular Openings in Elasto‐Brittle‐Plastic Rock Mass Based on Logarithmic Strain

Cited by 5 publications

References 10 publications

Space‐Time Distribution Laws of Tunnel Excavation Damaged Zones (EDZs) in Deep Mines and EDZ Prediction Modeling by Random Forest Regression

Space‐Time Distribution Laws of Tunnel Excavation Damaged Zones (EDZs) in Deep Mines and EDZ Prediction Modeling by Random Forest Regression

A New Numerical Finite Strain Procedure for a Circular Tunnel Excavated in Strain-Softening Rock Masses and Its Engineering Application

Analytical solution of circular tunnel in elastic-viscoplastic rock mass

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