scholarly journals Modified ground response curve (GRC) in strain-softening rock mass based on the generalized Zhang-Zhu strength criterion considering over-excavation

2021 ◽  
Author(s):  
Chen Xu ◽  
Caichu Xia ◽  
Changling Han
Keyword(s):  
Rock Mass ◽  
Response Curve ◽  
Strain Softening ◽  
Strength Criterion ◽  
Ground Response

The ground response curve of underwater tunnels, excavated in a strain-softening rock mass

2015 ◽  
Vol 8 (3) ◽  
pp. 323-359 ◽  
Author(s):  
Ahmad Fahimifar ◽  
Hamed Ghadami ◽  
Masoud Ahmadvand
Keyword(s):  
Rock Mass ◽  
Response Curve ◽  
Strain Softening ◽  
Ground Response

Study on Post-Failure Deformation and Residual Strength of Rock Mass Based on Hoek-Brown Criterion

2012 ◽  
Vol 170-173 ◽  
pp. 121-124
Author(s):  
Jian Xin Han ◽  
Xing Hua Tong ◽  
Lei Wang ◽  
Guo Fu Sun
Keyword(s):  
Rock Mass ◽  
Residual Strength ◽  
Strain Softening ◽  
Strain Curve ◽  
Strength Criterion ◽  
Stress Strain Curve ◽  
Strength Parameters ◽  
Softening Parameter ◽  
Residual Values ◽  
The Stability

In order to predict the stability of surrounding rock mass in geotechnical engineering, it is important to study the post-failure deformation property and residual strength of rock mass. Based on evolutional behavior of strength parameters, aiming at generalized Hoek-Brown strength criterion, selecting major principal strain as strain softening parameter, this paper presents the method of solving post-failure stress-strain curve . In numerical case, the effect of evolutional law of strength parameters ， and to deformation and residual strength is discussed and we can draw the following conclusions: the greater the residual values of ， are and the smaller the residual value of is, the post-failure strain softening curve falls more gently and the greater the residual strength is.

Numerical solutions for strain-softening surrounding rock under three-dimensional principal stress condition

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sheng Yu-ming ◽  
Li Chao ◽  
Xia Ming-yao ◽  
Zou Jin-feng
Keyword(s):  
Finite Element ◽  
Principal Stress ◽  
Stress Condition ◽  
Strain Softening ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Strength Criterion ◽  
Surrounding Rock ◽  
Flow Rule ◽  
Finite Element Software

Abstract In this study, elastoplastic model for the surrounding rock of axisymmetric circular tunnel is investigated under three-dimensional (3D) principal stress states. Novel numerical solutions for strain-softening surrounding rock were first proposed based on the modified 3D Hoek–Brown criterion and the associated flow rule. Under a 3D axisymmetric coordinate system, the distributions for stresses and displacement can be effectively determined on the basis of the redeveloped stress increment approach. The modified 3D Hoek–Brown strength criterion is also embedded into finite element software to characterize the yielding state of surrounding rock based on the modified yield surface and stress renewal algorithm. The Euler implicit constitutive integral algorithm and the consistent tangent stiffness matrix are reconstructed in terms of the 3D Hoek–Brown strength criterion. Therefore, the numerical solutions and finite element method (FEM) models for the deep buried tunnel under 3D principal stress condition are presented, so that the stability analysis of surrounding rock can be conducted in a direct and convenient way. The reliability of the proposed solutions was verified by comparison of the principal stresses obtained by the developed numerical approach and FEM model. From a practical point of view, the proposed approach can also be applied for the determination of ground response curve of the tunnel, which shows a satisfying accuracy compared with the measuring data.

scholarly journals Strength Assessment of Broken Rock Postgrouting Reinforcement Based on Initial Broken Rock Quality and Grouting Quality

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Hongfa Xu ◽  
Hansheng Geng ◽  
Feng Chen ◽  
Xiao Chen ◽  
Liangliang Qi
Keyword(s):  
Rock Mass ◽  
Internal Friction ◽  
Growth Rates ◽  
Strength Criterion ◽  
Friction Angle ◽  
Uniaxial Tensile ◽  
Strength Assessment ◽  
Uniaxial Tensile Strength ◽  
Quantitative Calculation ◽  
Grouting Reinforcement

To estimate postgrouting rock mass strength growth is important for engineering design. In this paper, using self-developed indoor pressure-grouting devices, 19 groups of test cubic blocks were made of the different water cement ratio grouting into the broken rock of three kinds of particle sizes. The shear strength parameters of each group under different conditions were tested. Then this paper presents a quantitative calculation method for predicting the strength growth of grouted broken rock. Relational equations were developed to investigate the relationship between the growth rates of uniaxial compressive strength (UCS), absolute value of uniaxial tensile strength (AUTS), internal friction angle, and cohesion for post- to pregrouting broken rock based on Mohr-Coulomb strength criterion. From previous test data, the empirical equation between the growth rate of UCS and the ratio of the initial rock mass UCS to the grout concretion UCS has been determined. The equations of the growth rates of the internal friction coefficient and UCS for grouting broken rock with rock mass rating (RMR) and its increment have been established. The calculated results are consistent with the experimental results. These observations are important for engineered design of grouting reinforcement for broken rock mass.

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