Comprehensive Evaluation of the Reinforcement Effect of Grouting in Broken Surrounding Rock in Deep Roadways

2022 ◽  
Author(s):  
Xiaolei Wang ◽  
Renwei Li ◽  
Zhengwu Liu ◽  
Dapeng Jiang ◽  
Zhigang Ji
Keyword(s):  
Comprehensive Evaluation ◽  
Surrounding Rock ◽  
Reinforcement Effect

scholarly journals Primary Investigation on Equivalent Anchoring Method of Jointed Rock Mass Tunnel and Its Engineering Application

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Min Gao ◽  
Shanpo Jia
Keyword(s):  
Rock Mass ◽  
Three Dimensional ◽  
Engineering Application ◽  
Friction Angle ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Surrounding Rock ◽  
Rock Masses ◽  
Reinforcement Effect ◽  
Rock Bolts

Rock bolts, one of the main support structures of the tunnel, can improve the stress state and mechanical properties of the surrounding rocks. The rock bolts are simulated by bar or beam elements in present numerical calculations for most 2D tunnel models. However, the methods of simulating rock bolt in three-dimensional models are rarely studied. Moreover, there are too many rock bolts in the long-span tunnel, which are hardly applied in the 3D numerical model. Therefore, an equivalent anchoring method for bolted rock masses needs to be further investigated. First, the jointed material model is modified to simulate the anisotropic properties of surrounding rock masses. Then, based on the theoretical analysis of rock bolts in reinforcing mechanical properties of the surrounding rock masses, the equivalent anchoring method of the jointed rock mass tunnel is numerically studied. The equivalent anchoring method is applied to the stability analysis of a diversion tunnel in Western China. From the calculation results, it could be found that the reinforcement effect of rock bolts could be equivalently simulated by increasing the mechanical parameter value of surrounding rocks. For the jointed rock mass tunnel, the cohesion and internal friction angle of the surrounding rocks are improved as 1.7 times and 1.2 times of the initial value, which can simulate the reinforcement effect of rock bolts. Comparing with analytical results, the improved internal friction angle is nearly consistent with analytical result. The reinforcement effect of rock bolts is simulated obviously when the mechanical parameters of surrounding rocks are increased simultaneously. The engineering application shows that the equivalent anchoring method can reasonably simulate the effect of rock bolts, which can provide reference for stability analysis of three-dimensional tunnel simulations.

The Numerical Analysis on Stability of Deep Roadway Support System

2012 ◽  
Vol 193-194 ◽  
pp. 687-692
Author(s):  
Zhen Yan Xiao ◽  
Yu Liu
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Support System ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Reinforcement Effect ◽  
Rock Bolts ◽  
Roadway Support

The effect of the roadway with no supporting and roadway that was reinforcement by rock bolts and anchor robs, anchor rod combined bolting shoring, anchor rod combined anchor rope and lining timbering was simulated by using numerical simulation software FLAC3D. The results showed that the deformation of no supporting roadway is maximal, and the maximal position is vault. The displacement of top floor and two side decreases after supported, which can reinforce surrounding rock. The reinforcement effect of the anchor rod combined anchor rope and lining timbering is best.

scholarly journals Key Factors Identification and Risk Assessment for the Stability of Deep Surrounding Rock in Coal Roadway

2019 ◽  
Vol 16 (15) ◽  
pp. 2802 ◽  
Author(s):  
Dongmei Huang ◽  
Weijun Li ◽  
Xikun Chang ◽  
Yunliang Tan
Keyword(s):  
Risk Assessment ◽  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Fuzzy Comprehensive Evaluation ◽  
Mining Area ◽  
Surrounding Rock ◽  
Risk Level ◽  
Affecting Factors ◽  
Key Factors ◽  
The Stability

In order to evaluate the stability of deep surrounding rock, all of the affecting factors should be theoretically identified. However, some factors have slight impacts on the stability of deep surrounding rock compared with others. To conduct an effective risk assessment, key factors should be first extracted. The analytic hierarchy process (AHP) and grey relation analysis (GRA) methods are integrated to determine the key factors. First, the AHP method is applied to sort the factors by calculating the weights of them. Seven out of fifteen factors are extracted as the key factors, which account for 80% of the weights. Further, the GCA method is used to validate the effects of these key factors by analyzing the correlation between the performance of each factor and that of the reference. Considering the influence of these key factors and experts’ judgements, the multilevel fuzzy comprehensive evaluation method is adopted to obtain the risk level of the deep surrounding rock stability. Finally, the risk assessment of the deep surrounding rock in the E-Zhuang coal mine of Chinese Xinwen Mining Area illustrates the operability of the proposed method.

Analysis of the Surrounding Rock's Stability Based on Fuzzy Comprehensive Evaluation Model

2012 ◽  
Vol 226-228 ◽  
pp. 1390-1395
Author(s):  
Xia Zhong Zheng ◽  
Qiao Ling Chen ◽  
Hua Fei Li ◽  
Peng Fei Shi
Keyword(s):  
Comprehensive Evaluation ◽  
Evaluation Model ◽  
Fuzzy Comprehensive Evaluation ◽  
Surrounding Rock ◽  
Underground Engineering ◽  
Rock Classification ◽  
Engineering Construction ◽  
Comprehensive Evaluation Model ◽  
Hydropower Engineering ◽  
The Stability

In underground engineering construction of water conservancy and hydropower engineering, determining surrounding rock excavation and supporting construction measures and parameters according to the classification of surrounding rock's stability is an effective method. In hydropower engineering field, it made some achievements of surrounding rock classification through the engineering geological mechanics parameters. but there are some problems in the application. After the study, this paper established a fuzzy comprehensive evaluation model to determine the stability of surrounding rock. Practice has proved it to be more reasonable.

Study of Tunnel Surrounding Rock Classification Based on Drifting Degree and Uncertainty Measurement

2013 ◽  
Vol 353-356 ◽  
pp. 1427-1432
Author(s):  
Lan Hu ◽  
Tao Li ◽  
Wen Ge Qiu
Keyword(s):  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Measurement Theory ◽  
Surrounding Rock ◽  
Classification Model ◽  
Rock Classification ◽  
Evaluation Standard ◽  
Uncertainty Measurement ◽  
Practical Engineering ◽  
Contrast Analysis

Based on contrast analysis of tunnel surrounding rock classification method, five basic indicators were selected as evaluation factors. Evaluation matrix was constructed by uncertainty measurement theory. Weight was established by introducing drifting degree concept. The principle of maximum membership degree was choosed as evaluation criterion.Then a tunnel surrounding rock classification model was built.This comprehensive evaluation method made full use of its own parameters and evaluation standard to completely avoid the subjective influence of traditional weights determination and the sample set, making itself more objectivity and accuracy, having a strong operability. The practical engineering showed that this model applied to tunnel surrounding rock classification was feasible and had certain superiority, providing a new way for tunnel surrounding rock classification.

scholarly journals Study on the Stability of Surrounding Rock of Underground Circular Cavern Based on the Anchor Reinforcement Effect

2018 ◽  
Vol 2018 ◽  
pp. 1-18
Author(s):  
Shuancheng Gu ◽  
Pan Zhou ◽  
Wei Sun ◽  
Chunhui Hu ◽  
Zhi Li ◽  
...  
Keyword(s):  
Analytical Solution ◽  
Quantitative Evaluation ◽  
Evaluation Method ◽  
Surrounding Rock ◽  
Theoretical Solution ◽  
Reinforcement Effect ◽  
Stability Coefficient ◽  
Rock Reinforcement ◽  
Stability Of Surrounding Rock ◽  
The Stability

Achieving a comprehensive and accurate understanding of the anchor reinforcement mechanism and a quantitative evaluation of the surrounding rock’s stability for an anchored underground cavern can provide an important theoretical basis for supporting and excavating the cavern. First, the composite bearing structure composed of the anchor and surrounding rock was defined as the surrounding rock reinforcement body by using the homogenization method, and a new method for evaluating the stability of surrounding rock by the surrounding rock reinforcement body deformation and damage degree was proposed. Second, based on the anchor reinforcement effect, the expression of the physical-mechanical parameters of the surrounding rock reinforcement body was deduced, and the analytical solution of stress and displacement of the surrounding rock reinforcement body was obtained. Finally, the stability coefficient of surrounding rock indicating the degree of the surrounding rock reinforcement body damage was defined. The research showed that the theoretical solution agreed well with the results of the numerical simulation, and the difference between the theoretical solution and the monitoring value was less than 10%, which verified the reliability of the method and the results of this paper. The design of the length and spacing of the anchor followed the principle of long but sparse and short but dense, and the pretightening force of the anchor and the stability coefficient of surrounding rock varied linearly. The analytical solution of this paper provides a theoretical reference for understanding the mechanism of anchor support and provides a quantitative evaluation method for the stability of surrounding rock. Compared with the traditional support design, the theory of this paper gives full play to the self-stability of the surrounding rock and the strength of the anchor, which is conducive to saving support costs and avoiding the construction limitations in some projects.

scholarly journals Study on Sensitivity Parameters Analysis of Grouting Reinforcement Underpassing Existing Subway Tunnel by Numerical Modeling

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Zaiqiang Hu ◽  
Bin Ma ◽  
Xingzhou Chen ◽  
Lili Chen
Keyword(s):  
Pore Pressure ◽  
Principal Stress ◽  
Surrounding Rock ◽  
Surface Settlement ◽  
Stress Difference ◽  
Reinforcement Effect ◽  
Subway Tunnel ◽  
Grouting Pressure ◽  
Grouting Reinforcement ◽  
The Stability

When carrying out construction that underpasses existing subway tunnels, the surrounding rock is frequently disturbed. Therefore, it can loosen easily and become unstable, which makes its stability difficult to control. Here, we considered an existing subway tunnel in a certain subway section and used orthogonal experiments to design a simulation program as well as the UDEC (Universal Distinct Element Code) simulation software to determine the influences of four factors (i.e., grout density, grouting pressure, dynamic shear force, and viscosity) on the grouting reinforcement effect. The following results were obtained: (1) the combination of the construction method and the grouting parameters strongly influences the reinforcement effect on the surrounding rock of the tunnel. The grouting pressure is not directly proportional to the stability of the surrounding rock. The dynamic adjustment of the relationship between the grouting pressure and the grout density can effectively improve the stress state of the surrounding rock of the tunnel, control surface settlement and deformation, and reduce the section reduction rate of the tunnel. (2) The distribution of joints is closely related to the failure area and form of the surrounding rock of the tunnel. For surrounding rock with well-developed joint fissures, an excessively high grouting pressure should not be used as they are unstable. (3) The effective bearing range of grouting-reinforced surrounding rock is dependent on the pore pressure and principal stress difference. The area where the pore pressure is 70–80% of the initial grouting pressure is the effective bearing range of the grouting-reinforced surrounding rock. The stability of the surrounding rock increases with decreasing principal stress difference and increasing range. (4) The actual monitored data show that the surface settlement can be effectively reduced by handling of grouting reinforcement parameters flexibly, which can meet the control standards.

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