The Study on Mechanical Properties of Karst Tunnel

2011 ◽  
Vol 243-249 ◽  
pp. 3399-3402
Author(s):  
Bin Li ◽  
Tai Yue Qi
Keyword(s):  
Mechanical Properties ◽  
Numerical Models ◽  
Side Wall ◽  
Surrounding Rock ◽  
Karst Tunnel ◽  
Safety Coefficient ◽  
Coefficient Distribution ◽  
Unfavorable Effect ◽  
Adverse Influence ◽  
The Stability

Several numerical models were built by FLAC3D to simulate tunnel with karst around spandrel, tunnel with karst around springe, tunnel with karst around inverted arch and tunnel with karst around side wall. The influence of karsts on the deformation of lining and the safety coefficient distribution of surrounding rock after excavation was analyzed. The results from the numerical modeling suggest as follows: karst around spandrel has extremely unfavorable effect on the deformation of lining and the safety of surrounding rock above the vault, karst around side wall also seriously affect the stability of tunnel due to the asymmetry pressure on tunnel caused by karst, consequently, auxiliary measures should be taken to handle these two cases; karst around springe and karst around inverted arch has limited adverse influence on the overall safety of tunnel, backfill measures are enough to handle these two cases.

Stability and Deformation Analysis for Excavation and Backfilling of Fushun West Open-Pit Coal Mine

2013 ◽  
Vol 353-356 ◽  
pp. 751-755 ◽  
Author(s):  
Yong Cheng Yan ◽  
Xian Zhang Ling ◽  
Feng Zhang ◽  
Jia Hui Wang
Keyword(s):  
Coal Mine ◽  
Slip Surface ◽  
Surrounding Rock ◽  
Open Pit ◽  
Deformation Analysis ◽  
Interface Model ◽  
Safety Coefficient ◽  
Mine Slope ◽  
The Stability ◽  
Technical Basis

Taking section W400 of Fushun west open-pit coal mine for the research, the interface model of fracture zone and surrounding rock was established. FLAC3D is used to analysis the influence of excavation and backfill of open-fit coal mine to the slope stability and deformation. The numerical results and analysis show that: (1) when the open-pit coal mine slope is excavated to final production line, the safety coefficient is 2.98, with the excavation, the deformation of the Fushun No.1 Refinery Factory area increases. (2) With the increase of backfilling, the slope coefficient increases to 3.32, this will reduce the deformation of the Fushun No.1 Refinery Factory area. Furthermore, the positions of the dangerous slip surface and serious deformation part of factory area should be regards as key areas. These conclusions could provide technical basis for the stability analysis of Fushun west open-pit coal mine.

scholarly journals Parameter optimization of double side wall method for soft surrounding rock tunnel

2019 ◽  
Vol 136 ◽  
pp. 04021
Author(s):  
Zhihua Yang ◽  
Rumiao He ◽  
Ke Li ◽  
Hongyan Guo
Keyword(s):  
Side Wall ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Surrounding Rock ◽  
Radius Of Curvature ◽  
Tunnel Excavation ◽  
The Stability ◽  
Rock Tunnel ◽  
Double Wall ◽  
Wall Method

When the Xiaojiazhai tunnel is constructed by the double-wall method, different curvature radii have different effects on controlling the stability of the surrounding rock and speeding up the construction progress. By numerically simulating the tunnel excavation under different radius of curvature, it is concluded that R is adopted respectively. The deformation displacement of surrounding rock is =11.6m∠520 and R=5.76m∠1060. The maximum horizontal displacement and vertical displacement are smaller when R=5.76m∠1060 is selected. According to the analysis results, when R=5.76m∠1060 is selected, the deformation of surrounding rock can be controlled to ensure the safety of construction and provide reference for future construction.

scholarly journals A Numerical Study of Underground Cavern Stability by Geostress Characteristics

2016 ◽  
Vol 2016 ◽  
pp. 1-13
Author(s):  
Xiao-Jing Li ◽  
Li-Ge Wang ◽  
Wei-Min Yang
Keyword(s):  
Numerical Study ◽  
Pressure Coefficient ◽  
Side Wall ◽  
Surrounding Rock ◽  
High Mountain ◽  
Burial Depth ◽  
Underground Cavern ◽  
Rock Cavern ◽  
The Stability ◽  
Cavern Stability

The stability of underground cavities is of increasing importance considering the predominant cavity locations built up in high mountain and canyon environments. Such cavity locations are characterized by a high initial in situ stress, which results in brittle fracture and deformation of the surrounding rock during cavity construction. This paper presents a numerical study of underground cavern stability considering four factors, namely, mechanical property of surrounding rock, cavern burial depth, lateral pressure coefficient in horizontal direction, and the angle included between plant longitudinal axis and horizontal principal stress. Analytical methods including the key point displacement in side wall, plastic zone volume, and splitting fracture volume are used to characterize the stability of underground cavern. A modified formula to predict side wall displacement is proposed based on prior work, which is applicable to 3D computation model by taking horizontal geostress in two directions into account. Eventually, the optimal layout of underground cavern is put forward under different conditions of geostress field.

scholarly journals Deformation Mechanism and Support Technology of Deep and High-Stress Soft Rock Roadway

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Lujing Zheng ◽  
Yujun Zuo ◽  
Yafei Hu ◽  
Wei Wu
Keyword(s):  
Mechanical Properties ◽  
Bearing Capacity ◽  
High Stress ◽  
Soft Rock ◽  
Physical And Mechanical Properties ◽  
Surrounding Rock ◽  
Rock Fragmentation ◽  
The Stability ◽  
Soft Rock Roadway ◽  
Rock Roadway

In this study, the analysis and control of stability of surrounding rock in deep fractured soft rock roadway located in the underground mine of Jinfeng gold mine in Guizhou Province, China, has been investigated. The surrounding rock of roadway has been analyzed to characterize its deformation and failure mechanism through field survey, testing of rock physical and mechanical properties, in situ stress measure, analysis of mineral components of rock, and investigation of rock fragmentation degree. Based on the numerical simulation technology, the influence of different factors on the stability of roadway is studied. The physical and mechanical properties of surrounding rock and the bearing capacity of surrounding rock layer are to be improved to maintain the stability of broken soft rock roadway as high ground stress, rock fragmentation, and poor lithology leading to tunnel instability. Hence, a high-strength “cable bolt + fiber-reinforced shotcrete + steel mesh + split sets + resin bolt + cement grouting” combined support system has been proposed to improve the effective bearing structure significantly with high integrity and bearing capacity.

Study of Safe Distance Criterion between Concealed Karst Cave and Tunnel

2014 ◽  
Vol 556-562 ◽  
pp. 849-852 ◽  
Author(s):  
Yong Biao Lai ◽  
Meng Shu Wang ◽  
Xin Hua You
Keyword(s):  
Surrounding Rock ◽  
Karst Cave ◽  
Instability Mechanism ◽  
Safe Distance ◽  
Rock Stratum ◽  
Safety Coefficient ◽  
Concealed Karst Cave ◽  
Comparison And Analysis ◽  
Simulation Results ◽  
The Stability

On the basis of analysis of the stability criterion of surrounding rock and instability mechanism of the rock stratum between concealed karst cave and tunnel, the rock stratum energy catastrophe and safety coefficient catastrophe as safe distance criterion between concealed karst cave and tunnel were put forward, then the comparison and analysis of numerical simulation results based on the run-through of plastic zone criterion, energy catastrophe criterion and safety coefficient catastrophe criterion were carried out with engineering examples, the results showed that energy catastrophe criterion was more reasonable.

A Study on the Influence by Karst on the Stability of Surrounding Rock in Neighborhood Tunnel

2012 ◽  
Vol 446-449 ◽  
pp. 2177-2181 ◽  
Author(s):  
Cheng Wang ◽  
Xiao Qiang Pi
Keyword(s):  
Side Wall ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Surrounding Rock ◽  
Tunnel Construction ◽  
Stability Of Surrounding Rock ◽  
Vertical Displacements ◽  
The Stability ◽  
Selection Of

Based on the Shuangbei tunnel, this paper studied influences on the deformation and stress of surrounding rock, regarding different Karst sizes and locations in such a neighborhood tunnel. The study indicates that variations of size and distance of the karst have prominent influence on the vertical displacements of vault and right side-wall in the tunnel near the karst, but have no influence on the horizontal displacement; while variation of karst size has prominent influence not only on the horizontal displacement, but also on the vertical displacement at the bottom of the tunnel far away from the karst; variations of size and distance of the karst have the prominent influence on the vault stress of the two tunnels. The results offer the reference to the tunnel construction and the selection of support type.

Analyzing the Strength and Stability of Large Underground Cavern Group with Different Generator Socket Construction Schemes Based on Three Dimensional Numerical Simulation

2007 ◽  
Vol 353-358 ◽  
pp. 2537-2540
Author(s):  
An Nan Jiang
Keyword(s):  
Three Dimensional ◽  
Side Wall ◽  
Surrounding Rock ◽  
Lower Side ◽  
Geological Investigation ◽  
Simulation Accuracy ◽  
Underground Powerhouse ◽  
Underground Cavern ◽  
Construction Step ◽  
The Stability

Shuibuya hydroelectric project is the most upstream power station in the Qingjiang cascade development of China. The power plant is designed as underground powerhouse, from seventh to eighth construction step, how to ensure the stability of surrounding rock mass of generator socket and controlling the displacement of lower side wall where the soft stratum located in is a key problem. To solve the problem, the three dimensional numerical model of the underground powerhouse was established based on the results of geological investigation. Then, the detailed construction processes, including the replacement of soft rock, excavation as well as support, were numerically simulated. In order to improve the simulation accuracy, the rock mechanics parameters were back analyzed based on in-situ monitor data before sixth construction step, then using Mohr-Coulomb criterion, the paper simulated and analyzed the damage zones of surrounding rock and displacement of lower side wall corresponding to different schemes. The best scheme was recommended by synthetically considering the stability indexes of each scheme. The study had a scientific meaning to guide Shuibuya project construction. Introduction When the underground cavern is excavated, the initial ground stress is released

scholarly journals Combined support mechanism of rock bolt and anchor cable for adjacent roadways in the external staggered split-level panel layout

2020 ◽  
Author(s):  
Adrian Batugin ◽  
Zhiqiang Wang ◽  
Wenyu Lv ◽  
Zehua Su ◽  
Shermatova Sayyora Sidikovna
Keyword(s):  
Mechanical Properties ◽  
Side Wall ◽  
Rock Bolt ◽  
Structure Characteristic ◽  
Thick Coal Seam ◽  
Support Mechanism ◽  
Anchor Cable ◽  
Side Rock ◽  
Air Intake ◽  
The Stability

Abstract Utilizing the spatial structure characteristic of the external staggered split-level panel layout, the combined support technology of adjacent roadways was proposed, and combined support mechanism of rock bolt and anchor cable was analyzed. The influence of side rock bolt and anchor cable parameters respectively on mechanical properties of the anchorage body and support stress distribution of lateral coal body were revealed through FLAC 3D software. The optimal support parameters of side rock bolt and anchor cable were determined subsequently. And the support effect of the gob-side entry under mining influence was verified. Result shows that the support of side rock bolt and anchor cable can improve mechanical properties and the stress state of the anchorage body, which has a good protective effect on the coal body of the air-intake entry roof and side wall. It is beneficial to the stability of the side wall and the realization of the suspension effect for the roof rock bolt and anchor cable, which makes the surrounding rock maintenance of the gob-side entry of the thick coal seam more favorable.

scholarly journals A Case Study on Large Deformation Failure Mechanism of Coal given Chamber and Invention of a New Wall-Mounted Coal Bunker in Xiashijie Coal Mine with Soft, Swelling Floor Rock

2017 ◽  
Author(s):  
Xingkai Wang ◽  
Wenbing Xie ◽  
Shengguo Jing ◽  
Jianbiao Bai ◽  
Zhili Su
Keyword(s):  
Failure Mechanism ◽  
Coal Mine ◽  
Numerical Models ◽  
Surrounding Rock ◽  
Engineering Practice ◽  
Floor Rock ◽  
Geological Conditions ◽  
Floor Heave ◽  
The Stability ◽  
Bearing Structure

Serious damage caused by floor heave in the coal given chamber of a vertical coal bunker is one of the challenges faced in underground coal mines. Engineering practice shows that it is more difficult to maintain the coal given chamber (CGC) than a roadway. More importantly, repairing the CGC during mining practice will pose major safety risks and reduce production. Based on the case of the serious collapse that occurred in the bearing structure of the CGC at the lower part of the 214# coal bunker in Xiashijie mine, China, this work analysed (i) the main factors influencing floor heave and (ii) the failure mechanism of the load-bearing structure in the CGC using FLAC2D numerical models and expansion experiment. The analysis results indicate that: the floor heave, caused mainly by mine water, is the basic reason leading to the instability and repeated failure of the CGC in the 214# coal bunker. Then a new coal bunker, without building the CGC, is proposed and put into practice to replace the 214# coal bunker. The FLAC3D software program is adopted to establish the numerical model of the wall-mounted coal bunker (WMCB), and the stability of the rock surrounding the WMCB is simulated and analysed. The results show that: (1) the rock surrounding the sandstone segment is basically stable. (2) The surrounding rock in the coal seam segment, which moves into the inside of the bunker, is the main zone of deformation for the entire rock mass surrounding the bunker. Then the surrounding rock is controlled effectively by means of high-strength bolt–cable combined supporting technology. According to the geological conditions of the WMCB, the self-bearing system, which includes (i) H-steel beams, (ii) H-steel brackets, and (iii) self-locking anchor cables, is established and serves as a substitute for the CGC to transfer the whole weight of the bunker to stable surrounding rock. The stability of the new coal bunker has been verified by field testing, and the coal mine has gained economic benefit to a value of 158.026174 million RMB over three years. The new WMCB thus made production more effective and can provide helpful references for construction of vertical bunkers under similar geological conditions.

Application of Stereographic Projection in the Search of Key Block of Surrounding Rock Mass for Underground Powerhouse

2010 ◽  
Vol 44-47 ◽  
pp. 1189-1192
Author(s):  
Zhong Chang Wang
Keyword(s):  
Rock Mass ◽  
Stereographic Projection ◽  
Side Wall ◽  
Surrounding Rock ◽  
Main Role ◽  
Measuring Point ◽  
Underground Powerhouse ◽  
Underground Caverns ◽  
Key Block ◽  
The Stability

The rose diagram of joint is generalized by grouping the attitude of disclosed discontinuous faces in detecting cavern and measuring point coordinate. The search of movable and key blocks of surrounding rock mass for underground powerhouse is implemented, the combinations of discontinuous faces and sliding faces, the location and the parameter of stability of movable and key blocks are obtained by used of the method of stereographic projection and vector analysis of the block theory. It is shown that the numbers of movable and key blocks in the location of downriver right side wall and vault are larger than those in other location owing to numerous discontinuous faces, and the faults of F34 and F33 play a main role in the stability of movable and key blocks. The guidance for excavation and reinforce of underground caverns is provided.

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