Research on Control Technology and Structural Characteristics of Very Instable Surrounding Rocks in Structural Belt

2011 ◽  
Vol 261-263 ◽  
pp. 1743-1748
Author(s):  
Yong Jian Zhu
Keyword(s):  
Structural Characteristics ◽  
Surrounding Rock ◽  
Actual State ◽  
Rock Support ◽  
Before And After ◽  
Deformation Amount ◽  
Deformation Speed ◽  
Grouting Reinforcement ◽  
Failure Depth ◽  
Two Sides

According to the actual state of the 1150 horizontal main haulageway of Tailai colliery is in the affected areas of many faults, both on the roof to floor and two sides convergences are about 1000mm,the YTJ20 strata structure detector was used to detect the strata structure character of the roadway roof, it showed the surrounding rock of 1150 horizontal main haulageway is very broken and the maximum failure depth reached to 6m; meanwhile we took 4 group of rock samples from the broken zone to carry out x diffraction, the results showed that the surrounding rock in the broken contained high expansibility rock, so measure of rock surrounding grouting reinforcement was proposed without changing the original supporting parameters. Comparative analysis of rock surrounding reinforcement effect before and after grouting was calculated by FLAC simulation soft. The result shows only supported “bolts + shotcrete layer + cables”, both the deformation speed and deformation amount are very obviously, the community of “rock-support” shows loose and breaking state; But using the combined supporting method of grouting reinforcement and “bolts + shotcrete layer + cables”, the surrounding rock deformation obtained effectively control with less stress release, the community of “rock-support” shows higher integrity degree, It can ensure the safe use of the roadway.

scholarly journals Effect analysis of grouting reinforcement ring considering fluid solid coupling

2019 ◽  
Vol 277 ◽  
pp. 03014
Author(s):  
Heng Zhou ◽  
Xiaochen Wang ◽  
Haojie Liu ◽  
Yanan Liu ◽  
Chenyang Ma ◽  
...  
Keyword(s):  
Surrounding Rock ◽  
Physical Parameters ◽  
Sand Layer ◽  
Effect Analysis ◽  
Reinforcement Ring ◽  
Before And After ◽  
Grouting Reinforcement ◽  
Set Up ◽  
Subway Tunnels ◽  
The Relationship

Geological hazards such as instability of surrounding rock and leakage of water are easily occurred in subway tunnels crossing water rich sand layers. Based on the principle of fluid solid coupling in porous media, this paper studies the plastic zone distribution of surrounding rock and reinforcement ring, vertical settlement of tunnel vault and water seepage of tunnel before and after grouting reinforcement for water rich sand layer. Considering the compressibility of rock mass, the relationship between porosity, permeability and volume strain is further deduced and simplified. A set of numerical calculation formula is set up to study the change of physical parameters of the water rich sand layer before and after grouting to determine the grouting effect and select the thickness of the best grouting reinforcement ring. The results show that the deformation and water permeability of the tunnel decrease with the increase of the thickness of the grouting reinforcement ring. The thickness of the grouting reinforcement ring is the most reasonable when the thickness of the reinforcing ring reaches a certain value, and the thickness of the grouting reinforcement ring is designed to be 5~6m. The research results have been successfully applied in the grouting project of Qingdao Metro stone elderly bathing beach. The reliability of the numerical simulation is verified by comparing the data from the field monitoring and measurement, providing reference for the related projects.

scholarly journals Deformation Mechanism and Control Technology of the Surrounding Rock of the Floor Roadway under the Influence of Mining

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Qingchong Zhao ◽  
Baojie Fu ◽  
Jiadi Yin
Keyword(s):  
Numerical Simulation ◽  
Surface Displacement ◽  
Surrounding Rock ◽  
Infinite Body ◽  
Maximum Displacement ◽  
Deformation And Failure ◽  
Working Face ◽  
Before And After ◽  
Stress And Deformation ◽  
Two Sides

Deformation and failure mechanism of the surrounding rock of the floor roadway under the influence of working face mining is complicated, and roadway control is difficult. The floor roadway of the 11123 working face in Pan’er Mine is taken as the research object of this study based on semi-infinite body theory of elastic mechanics to establish a mechanical model along the advancing direction of the working face and derive the stress expression of any point in the affected area of floor mining. According to the theoretical results, effective reinforcement and support schemes are then proposed. FLAC3D numerical simulation analyzes the stress and deformation of the surrounding rock of the floor roadway before and after the reinforcement. The numerical simulation results showed that (1) mining abutment pressure of the overlying working face forms a certain range of stress concentration on the roof and two sides of the roadway and will cause deformation and damage to the floor roadway and (2) overall bearing capacity of the surrounding rock of the roadway is significantly improved, and surface displacement of the floor roadway is reduced by 64 mm through the reinforcement and support of the floor roadway. On-site monitoring data of the floor roadway in the 11123 working face of Pan’er Mine showed that the maximum displacement of the roadway roof and two sides is controlled at approximately 80 mm, and the surrounding rock deformation of the roadway is appropriately controlled to meet the needs of safe production.

scholarly journals Physicochemical and structural characteristics of HEU-type zeolitic tuff treated by hydrochloric acid

2004 ◽  
Vol 69 (4) ◽  
pp. 273-282 ◽  
Author(s):  
Ana Radosavljevic-Mihajlovic ◽  
Vera Dondur ◽  
Aleksandra Dakovic ◽  
Jovan Lemic ◽  
Magdalena Tomasevic-Canovic
Keyword(s):  
Crystal Structure ◽  
Hydrochloric Acid ◽  
Bosnia And Herzegovina ◽  
Acid Treatment ◽  
Structural Characteristics ◽  
Chemical Analyses ◽  
Zeolitic Tuff ◽  
Zeolitic Tuffs ◽  
Before And After

Samples of natural HEU-type zeolites ? clinoptilolite-Ca, from the Novakovici deposit (near Prijedor, Bosnia and Herzegovina) were treated with the hydrochloric acid of various concentrations (from 10-3Mto 2M). Zeolitic tuffs before and after the acid treatment were examined using IR, XRPD, and chemical analyses. The changes in the crystal structure of acid treated samples showed a significant reduction in the crystallinity of zeolitic tuffs (60?70 %), which were effected by hydrochloric acid with concentrations of 1 M and above.

scholarly journals Movement Laws of Overlying Strata above a Fully Mechanized Coal Mining Face Backfilled with Gangue: A Case Study in Jiulishan Coal Mine in Henan Province, China

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Zhengkai Yang ◽  
Zhiheng Cheng ◽  
Zhenhua Li ◽  
Chunyuan Li ◽  
Lei Wang ◽  
...  
Keyword(s):  
Coal Mining ◽  
Main Roof ◽  
Surrounding Rock ◽  
Surface Subsidence ◽  
Key Strata ◽  
Key Stratum ◽  
Mining Face ◽  
Failure Depth ◽  
Gangue Backfilling ◽  
Overlying Strata

The aim of this study is to obtain movement laws of overlying strata above a fully mechanized coal mining face backfilled with gangue and solve the problem of surface subsidence during coal mining. This study was carried out based on gangue backfilling mining of Jiulishan Coal Mine (Jiaozuo City, Henan Province, China) from the perspectives of deformation of backfilled gangue under compaction, surrounding rock of a stope, and activities of key strata. The method combining with rock mechanics, viscoelastic mechanics, control theory of rock mass under mining, and numerical simulation was used based on physical and mechanical characteristics of backfilled gangue. On this basis, the research analyzed the temporal-spatial relationships of activities of surrounding rock of the stope, compressive deformation of backfilling body, failure depth of the floor, deformation characteristics of the main roof with laws of surface subsidence. The movement characteristics of overlying strata above the fully mechanized coal mining face backfilled with gangue and the traditional fully mechanized mining face were compared. It is found that, under the same conditions of overlying strata, movement laws of overlying strata are mainly determined by the mining height of coal seams and the heights of a caving zone and a fracture zone are nearly linearly correlated with the mining height. Through analysis based on thin-plate theory and key stratum theory, the location of the main roof of the fully mechanized coal mining face backfilled with gangue in coal seams first bending and sinking due to load of overlying strata was ascertained. Then, it was determined that there are two key strata and the main roof belongs to the inferior key stratum. By using the established mechanical model for the main roof of the fully mechanized coal mining face backfilled with gangue and the calculation formula for the maximum deflection of the main roof, this research presented the conditions for breaking of the main roof. In addition, based on the theoretical analysis, it is concluded that the main roof of the fully mechanized coal mining face backfilled with gangue does not break, but bends. The numerical simulation results demonstrate that, with the continuous increase of strength of backfilled gangue, the stress concentration degree of surrounding rock reduces constantly, so does its decrease amplitude. Moreover, the compressive deformation of backfilling, failure depth of the floor, and bending and subsidence of the main roof continuously decrease and tend to be stable. The mechanical properties of backfilling materials determine effects of gangue backfilling in controlling surface subsidence. Gangue backfilling can effectively control movement of overlying strata and surface subsidence tends to be stable with the increase of elastic modulus of gangue.

Review Microstructure of Nickel-Based Single-Crystal CMSX-4 Superalloy after Electrochemical Machining

2021 ◽  
Author(s):  
Ali Mehrvar ◽  
Alireza Mirak ◽  
Mohsen Motamedi
Keyword(s):  
Single Crystal ◽  
Electrochemical Machining ◽  
Free Surfaces ◽  
Gamma Prime ◽  
Eds Analysis ◽  
Metal Machining ◽  
Before And After ◽  
Gamma Field ◽  
High Level ◽  
Two Sides

Abstract A special position has been created for using the nickel-based single-crystal CMSX-4 superalloy at high temperatures due to the improved mechanical properties of this material and the absence of grain boundary in the crystal lattice. Also, electrochemical machining can be an effective method for machining this superalloy due to its unique performance in metal machining, like creating stress-free surfaces, high-level surface smoothness, and machining of complex geometries. This single crystal superalloy's microstructure consists of three phases: Gamma, Gamma prime, and a bit of carbide. Gamma prime is distributed cubically and homogeneously in the Gamma field without any boundaries and as a single crystal. It is essential not to change the microstructure after the production process or machining. In the present research, electrochemical machining was performed on CMSX-4 single crystal superalloy. The workpiece's microstructure was then investigated before and after electrochemical machining using scanning electron microscopy and EDS analysis from two sides. No changes were seen in CMSX-4 infrastructure after electrochemical machining EDS analysis and Images.

Study on the Influence of Nonlinear Seepage and Grouting Reinforcement on Surrounding Rock in Subsea Tunnel

2020 ◽  
Vol 111 (sp1) ◽  
Author(s):  
Xiaonan He ◽  
Xiaomin Zhou ◽  
Yan Xu ◽  
Wenzhu Ma ◽  
Tao Wu
Keyword(s):  
Surrounding Rock ◽  
Subsea Tunnel ◽  
Grouting Reinforcement

scholarly journals Displacement Solution of Salt Cavern with Shear Dilatation Behavior Based on Hoek-Brown Strength Criterion

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Huabin Zhang ◽  
Qingqing Zhang ◽  
Laigui Wang
Keyword(s):  
Plastic Zone ◽  
Elastic Strain ◽  
Large Strain ◽  
Structural Characteristics ◽  
Strength Criterion ◽  
Surrounding Rock ◽  
Salt Formation ◽  
Salt Cavern ◽  
The Stability ◽  
Influence Degree

In this study, an analytical solution of stress, strain, and displacement, in the elastic and plastic zone is proposed. The solution is derived on the basis of ideal elastoplastic mechanical model of spherical salt cavern with shear dilatation behavior, by adopting Hoek-Brown (H-B) criterion. The solution obtains not only in small and large strain stage but also in creep stage. The proposed solution is validated, by comparison of the obtained results with numerical results in FLAC3D. The results indicate that the result obtained adopting the H-B criterion is closer to that one obtained adopting the Mohr-Coulomb (M-C). The H-B criterion is more applicable for the salt cavern construction as it considers the structural characteristics of the rock salt formation. The displacement difference obtained by two different methods decreases with the increase of GSI or running pressure, but it increases with the enlarged angle of dilation. The influence of different assumptions of elastic strain of plastic zone on displacements is more significant under large strain conditions. The influence of the angle of dilation on displacements is more obvious when the elastic strain of plastic zone is given to stationary values, and the influence degree increases with the enlarged angle of dilation. Under the same conditions, the creep displacement decreases with the increase of GSI, and both the creep displacement and the effect degree enhance with the enlarged dilation angle. The proposed solutions can be used in the stability analysis of surrounding rock in the construction and operation of salt cavern storage.

scholarly journals Safety Threshold Determination for Blasting Vibration of the Lining in Existing Tunnels under Adjacent Tunnel Blasting

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Fei Xue ◽  
Caichu Xia ◽  
Guoliang Li ◽  
Baocheng Jin ◽  
Yongwang He ◽  
...  
Keyword(s):  
Surrounding Rock ◽  
Blasting Vibration ◽  
Vibration Data ◽  
Maximum Charge ◽  
Blasting Excavation ◽  
Tunnel Blasting ◽  
Before And After ◽  
Rock Tunnel ◽  
A Site ◽  
Site Test

The effects of tunnel blast excavation on the lining structures of adjacent tunnels are comprehensively studied for the Xinling highway tunnel project. First, the LS-DYNA software is applied to obtain the characteristics of vibration velocities and dynamic stresses at different positions of the tunnel liner. The results indicate that the maximum peak particle velocity (PPV) is located on the haunch of the lining facing the blasting source and that the PPV and peak tensile stress decrease with the increase in the surrounding rock grade. Second, a site test on blasting vibration is conducted to verify the simulation results. By using regression analysis of the measured vibration data, the calculation method of maximum charge per delay for optimizing blasting excavation under different surrounding rock grades is obtained. Finally, based on the statistical relationship between crack alteration and PPV on the lining before and after blasting, the safety thresholds of PPV for different portions of the tunnel are determined. The recommended safety threshold of PPV is 10 cm/s for intact lining and for B-grade and V-grade linings of the surrounding rock tunnel. However, if the lining crack grade falls between 1A and B, then the recommended safety thresholds of PPV for the III-grade and IV-grade surrounding rock tunnel are 5 cm/s and 6 cm/s, respectively. The threshold PPV proposed in this study has been successfully applied to restrict blast-induced damage during new tunnel excavation of the Xinling tunnel project.

Study of Stability of Surrounding Rock and Structural Characteristics of Large Long Corridor Surge Chamber

2014 ◽  
Vol 912-914 ◽  
pp. 774-782
Author(s):  
Jian Feng Yin
Keyword(s):  
Finite Difference Method ◽  
Plastic Zone ◽  
Structural Characteristics ◽  
Underground Structure ◽  
Surrounding Rock ◽  
Hydropower Station ◽  
Unique Form ◽  
Structure Form ◽  
Stability Of Surrounding Rock ◽  
The Finite Difference Method

Large long corridor surge chambers have unique form. As a typical hydropower underground structure, its stability of surrounding rock in the process of excavation and force features of structure are affected by particular structure form. Take a hydropower station for example, by using the finite difference method, we simulated two different schemes in process of excavation and analyzed its displacement, stress, plastic zone of surrounding rock as well as force feature of structure. Appropriate law of large long corridor surge chamber during excavation is summarized which will provide the reference for the similar project.

A Case Study of Distress Detection and Treatment of Loess Road Tunnel

2011 ◽  
Vol 474-476 ◽  
pp. 1787-1791
Author(s):  
Jin Xing Lai ◽  
Guang Long Zhang ◽  
Xiao Wei Liu
Keyword(s):  
Surrounding Rock ◽  
Cost Estimate ◽  
System Stability ◽  
Road Tunnel ◽  
Stability Of Surrounding Rock ◽  
Before And After ◽  
Lining Structure ◽  
Water Proof ◽  
Slurry Injection

Based on the characteristic of distress in Qijia mountain road tunnel, thickness, cavity distribution, crevice water were detected with geo-radar. Material of lining was nondestructive detected with sound locater. Limiting structure of the tunnel was detected with circumscription apparatus. Based on detected results cause of the distress was analyzed. Three treatment schemes were put forward by slurry injection from the back of lining structure, reinforcement lining, treating the water proof system. Stability of surrounding rock and the state of forces of the lining structure were analyzed before and after treatment. It is showed that the treatment scheme of the tunnel is feasible. Taken construction and cost estimate into account, optimal scheme is obtained.

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