scholarly journals Model Test of Anchoring Effect on Zonal Disintegration in Deep Surrounding Rock Masses

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Xu-Guang Chen ◽  
Qiang-Yong Zhang ◽  
Yuan Wang ◽  
De-Jun Liu ◽  
Ning Zhang
Keyword(s):  
Model Test ◽  
Surrounding Rock ◽  
Zonal Disintegration ◽  
Formation Condition ◽  
Anchor Effect ◽  
Rock Masses ◽  
Tunnel Excavation ◽  
Anchoring Effect ◽  
Tension And Compression ◽  
Deep Rock

The deep rock masses show a different mechanical behavior compared with the shallow rock masses. They are classified into alternating fractured and intact zones during the excavation, which is known as zonal disintegration. Such phenomenon is a great disaster and will induce the different excavation and anchoring methodology. In this study, a 3D geomechanics model test was conducted to research the anchoring effect of zonal disintegration. The model was constructed with anchoring in a half and nonanchoring in the other half, to compare with each other. The optical extensometer and optical sensor were adopted to measure the displacement and strain changing law in the model test. The displacement laws of the deep surrounding rocks were obtained and found to be nonmonotonic versus the distance to the periphery. Zonal disintegration occurs in the area without anchoring and did not occur in the model under anchoring condition. By contrasting the phenomenon, the anchor effect of restraining zonal disintegration was revealed. And the formation condition of zonal disintegration was decided. In the procedure of tunnel excavation, the anchor strain was found to be alternation in tension and compression. It indicates that anchor will show the nonmonotonic law during suppressing the zonal disintegration.

scholarly journals Analysis on Water Inrush Process of Tunnel with Large Buried Depth and High Water Pressure

Processes ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 134 ◽  
Author(s):  
Weimin Yang ◽  
Zhongdong Fang ◽  
Hao Wang ◽  
Liping Li ◽  
Shaoshuai Shi ◽  
...  
Keyword(s):  
High Pressure ◽  
Model Test ◽  
Water Pressure ◽  
Water Inrush ◽  
High Water ◽  
Surrounding Rock ◽  
Karst Cave ◽  
Tunnel Excavation ◽  
Pressure Water ◽  
High Water Pressure

In order to explore the catastrophic evolution process for karst cave water inrush in large buried depth and high water pressure tunnels, a model test system was developed, and a similar fluid–solid coupled material was found. A model of the catastrophic evolution of water inrush was developed based on the Xiema Tunnel, and the experimental section was simulated using the finite element method. By analyzing the interaction between groundwater and the surrounding rocks during tunnel excavation, the law of occurrence of water inrush disaster was summarized. The water inrush process of a karst cave containing high-pressure water was divided into three stages: the production of a water flowing fracture, the expansion of the water flowing fracture, and the connection of the water flowing fracture. The main cause of water inrush in karst caves is the penetration and weakening of high-pressure water on the surrounding rock. This effect is becoming more and more obvious as tunnel excavation progresses. The numerical simulation results showed that the outburst prevention thickness of the surrounding rock is 4.5 m, and that of the model test result is 5 m. Thus, the results of the two methods are relatively close to each other. This work is important for studying the impact of groundwater on underground engineering, and it is of great significance to avoid water inrush in tunnels.

Numerical Study on Zonal Disintegration of Deep Rock Mass Using Three-Dimensional Bonded Block Model

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Qingteng Tang ◽  
Wenbing Xie ◽  
Xingkai Wang ◽  
Zhili Su ◽  
Jinhai Xu
Keyword(s):  
Rock Mass ◽  
Fracture Zone ◽  
Numerical Study ◽  
Confining Pressure ◽  
Surrounding Rock ◽  
Zonal Disintegration ◽  
Block Model ◽  
Deep Rock Mass ◽  
Damaged Zone ◽  
Deep Rock

Zonal disintegration, a phenomenon of fractured zones and intact zones distributed alternately in deep rock mass, is different from the excavation-damaged zone of shallow rock mass. In this study, bonded block model of 3DEC was employed to study the fracture mode and origination condition of zonal disintegration. Initiation, propagation, and coalescence progress of fracture around the roadway boundary under different triaxial stress conditions are elaborated. Numerical simulation demonstrated that zonal disintegration may occur when the direction of maximum principal stress is parallel to the roadway axis. It is interesting to find that the fracture around the roadway boundary traced the line of a spiral line, while slip-line fractures distributed apart from the roadway boundary. The extent of the alternate fracture zone decreased as the confining pressure increased, and alternate fracture zone was no longer in existence when the confining pressure reaches a certain value. Effects of roadway shape on zonal disintegration were also studied, and the results indicated that the curvature of the fracture track line tends to be equal to the roadway boundary in shallow surrounding rock of the roadway, while the fractures in deep surrounding rock seems unaffected by the roadway shape. Those findings are of great significance to support design of deep underground openings.

Research on Similar Materials for Rheological Test of Hard Rock Mass

2017 ◽  
Vol 744 ◽  
pp. 169-173
Author(s):  
Long Yun Zhang ◽  
Shang Yang Yang
Keyword(s):  
Rock Mass ◽  
Model Test ◽  
Rheological Behavior ◽  
Mechanical Model ◽  
Mechanical Tests ◽  
Surrounding Rock ◽  
Hydropower Station ◽  
Similar Material ◽  
Geological Conditions ◽  
Deep Rock

The analog material, used in the Geo-mechanical model test that is designed to study the unloading rheological behavior and failure characteristics of rock mass, must reflect the physico-mechanical behaviors of the actual rock mass. The surrounding rock of Meng-di-gou hydropower station is in complex geological conditions. With the excavation of the rock mass, the surrounding rock gradually unloading, and the property of the near rock mass. It is necessary to carry out Geo-mechanical model test to study the rheological properties of deep rock mass under complicated geological conditions. So the similar material, comprised of iron powder, barite powder, and quartz sands bound with a solution of alcohol and colophonium, is suggested to be improvable. Firstly, through more than 300 groups of mix proportion tests, the influence of different mix proportions of the ingredients are analyzed to obtain the optimal analog materials; Secondly, more than 1200 specimens are made into size Φ50mm×100mm; Lastly, physico-mechanical tests were conducted by using the specimens to test the mechanical property of the similar material, and the basic physico-mechanical parameters are obtained from the analog material. The results indicates that the property of the similar material matches well with that of the rock mass in site, so the similar material is suitable for the Geo-mechanical model test, and it can be used to test the unloading rheological behavior of rock mass of Meng-di-gou hydropower station.

Research on Support Technique for Excavation Process of Deep Rock Mass

2013 ◽  
Vol 438-439 ◽  
pp. 1249-1252
Author(s):  
Hong Xiao Wu ◽  
Song Lin Yue ◽  
Cun Cheng Shi ◽  
Xiao Hu ◽  
Cheng Chu ◽  
...  
Keyword(s):  
Rock Mass ◽  
High Strength ◽  
Surrounding Rock ◽  
Support Program ◽  
Tunnel Excavation ◽  
Deep Rock Mass ◽  
Rock Stability ◽  
Excavation Process ◽  
Deep Rock ◽  
Fracturing Mechanism

In the deep rock mass surrounding, rock burst, large deformation, zonal fracturing and phenomena like these may occur in the tunnel excavation process. When zonal fracturing happens, it is essential to reconsider the types of support, the boundary of support and the approach of tunnel excavation. In this paper, the control theory about the surrounding rock stability under high pre-existing stresses was researched, and the efficient support form which was the combination of high strength anchor bar and anchor cable was ascertained to be adaptive to deep tunnel excavation. According to the deformation and zonal fracturing mechanism of the surrounding rock, a comprehensive support program that combined intensive short anchor bars and long anchor cables was established, and the numerical simulation was carried out to verify the feasibility of the support form.

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