scholarly journals Study on Mutual Feedback Mechanism and Stability Control of Toppling Slope and Tunnels with High Excavation Rate

2021 ◽  
Vol 2076 (1) ◽  
pp. 012075
Author(s):  
Huifeng Zheng ◽  
Shuo Zheng ◽  
Yi Chen ◽  
Guanye Wu ◽  
Yong Zhou
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Great Difficulty ◽  
Stability Control ◽  
Feedback Mechanism ◽  
Western China ◽  
Left Bank ◽  
Deformation Control ◽  
Geological Conditions ◽  
Horizontal Partitioning

Abstract During the construction of large-scale hydropower projects in deep mountain gorge areas of the Western China, the difficulties, such as uncontrollable large deformation, great deformation caused by small disturbance, are often encountered in the process of implementation. In particular, due to the limitation of topography, geological conditions and the layout of structures, the slope and dense tunnel group with large section need to be excavated simultaneously in the toppling rock mass. The feedback action mechanism between slope and tunnel excavation is complicated and the deformation control of toppling rock is difficult, which leads to great challenges to engineering construction. In MW hydropower project in west of China, the intake slope, the spillway channel slope, four headrace tunnels, and the sand flushing tunnel, as well as the construction traffic tunnel are arranged in Huishi Ridge on the left bank, where two high slopes and six lager cross-section tunnels are simultaneously excavated and the excavation rate in the toppling deformation rock mass is over 50%, moreover, the lateral coverage thickness of tunnel body is less than the diameter of the tunnel, which leads to the great difficulty of stability control. The excavation stability and safe of the thin mountain ridge is the vital issue to the success of the whole project. Based on the study of the physical and mechanical parameters of toppling rock mass of MW HPP, the mutual feedback mechanism of toppling slope and tunnel group is revealed, an excavation method involving horizontal partitioning, vertical layering, reserving rock plug and reasonable skipping warehouse is proposed. Monitoring results shows that the slope and surrounding rock of the tunnels are stable during the operation period. The research of this paper based on the MW HPP can provide reference for other similar projects.

scholarly journals Key Factors Affecting the Deformation and Failure of Surrounding Rock Masses in Large-Scale Underground Powerhouses

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Meng Wang ◽  
Jia-wen Zhou ◽  
An-chi Shi ◽  
Jin-qi Han ◽  
Hai-bo Li
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Surrounding Rock ◽  
Rock Masses ◽  
Affecting Factors ◽  
Key Factors ◽  
Underground Powerhouse ◽  
Deformation And Failure ◽  
Factors Affecting ◽  
Geological Conditions

The stability of the surrounding rock masses of underground powerhouses is always emphasized during the construction period. With the general trends toward large-scale, complex geological conditions and the rapid construction progress of underground powerhouses, deformation and failure issues of the surrounding rock mass can emerge, putting the safety of construction and operation in jeopardy and causing enormous economic loss. To solve these problems, an understanding of the origins and key affecting factors is required. Based on domestic large-scale underground powerhouse cases in the past two decades, key factors affecting the deformation and failure of the surrounding rock mass are summarized in this paper. Among these factors, the two most fundamental factors are the rock mass properties and in situ stress, which impart tremendous impacts on surrounding rock mass stability in a number of cases. Excavation is a prerequisite of surrounding rock mass failure and support that is classified as part of the construction process and plays a pivotal role in preventing and arresting deformation and failure. Additionally, the layout and structure of the powerhouse are consequential. The interrelation and interaction of these factors are discussed at the end of this paper. The results can hopefully advance the understanding of the deformation and failure of surrounding rock masses and provide a reference for design and construction with respect to hydroelectric underground powerhouses.

scholarly journals Deformation Rules for Surrounding Rock in Directional Weakening of End Roofs of Thin Bedrocks and Ultrathick Seams

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Fei Liu ◽  
Zhanguo Ma ◽  
Yongsheng Han ◽  
Zhimin Huang
Keyword(s):  
Abutment Pressure ◽  
Main Roof ◽  
Stability Control ◽  
Surrounding Rock ◽  
Western China ◽  
Resource Exploitation ◽  
Failure Characteristics ◽  
Key Strata ◽  
Working Face ◽  
Geological Conditions

With the deployment of China’s energy strategy in the western regions, complex geological mining conditions such as thin bedrock and ultrathick seams in western China have caused a series of problems such as serious deformation of the surrounding rock at the ends of the working face and the increase in the lead abutment pressure of the roadways; the research on end roof deformation in the resource exploitation in western China has become one of the great demands of the industry. Based on the failure characteristics of rock mass, relying on the actual mining geological conditions of a coal mine in Inner Mongolia, the failure characteristics of the overlying rock strata under the influence of mining were simulated and analyzed using similar material simulation experiment, which intuitively reproduced the failure and deformation processes of the immediate roof, main roof, and key strata and revealed the mechanical mechanism of the directional weakening of the end roof. It is of great significance for the stability control of the surrounding rock at the end of the fully mechanized caving face in the thin bedrocks and ultrathick seams, reducing the abutment pressure of gate roadway and controlling the spontaneous combustion of residual coal in the goaf.

Landslide stabilization experience in Urtui open pit mine

2021 ◽  
pp. 102-106
Author(s):  
O. A. Isyanov ◽  
◽  
D. I. Ilderov ◽  
V. I. Suprun ◽  
S. A. Radchenko ◽  
...  
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Geological Structure ◽  
Stability Control ◽  
Open Pit Mine ◽  
Open Pit ◽  
Open Pit Mining ◽  
Coal Seams ◽  
Mining Operations ◽  
Early Access

Instability of pit wall slopes is the most critical accident in open pit mining. The risk of damages to pit walls is proportional to the height of exposed surfaces and to the time of exposure. Among many factors governing pit wall stability, the major factor is geological structure and weakening zones in rock mass. Deformation processes are initiated in host rock mass of coal seams mostly because of undercutting of weak interlayers. Alongside with local undercutting, another cause of landslides is transition of coal mining from down-dip extraction to up-dip extraction. The sequence of mining and morphology of weak interlayers also have influence on initiation and evolution of deformations. The basic component of engineering solutions on pit wall stability control is optimization of mining sequence and methods of accessing working horizons in open pit mines. Large-scale deformation of Western and Southeastern pit walls in Urtui mine could be avoided using the optimized sequence of mining operations. For example, mining advance mostly along the curve of the Urtui centroclinal fold, with early access and destress of the eastern and, first of all, western wings of the fold could make it possible to evade from up-dip mining of coal seams and, as a consequence, to solve the major geomechanical problems in the open pit mine.

scholarly journals The Challenges of Open-Pit Mining in the Vicinity of the Salt Dome (Bełchatów Lignite Deposit, Poland)

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1913
Author(s):  
Marek Cała ◽  
Katarzyna Cyran ◽  
Joanna Jakóbczyk ◽  
Michał Kowalski
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Salt Dome ◽  
Open Pit ◽  
Open Pit Mining ◽  
Stability Conditions ◽  
Mining Operations ◽  
Mass Behavior ◽  
Geological Conditions ◽  
Wall Slope

The extraction of the Bełchatów lignite deposit located in the vicinity of the Dębina salt dome requires careful planning that considers the influence of mining projects on the slope and salt dome stability conditions. The instability problem is directly related to horizontal and vertical displacement, as well as the complex geological and mining conditions. These conditions are very unique with regard to the co-occurrence of the salt dome and lignite deposits in the same area, as well as the large scale of the pit wall slope. Thus, predicting rock mass behavior and ensuring the safety of mining operations are important issues. The presented analysis focused on the influence of long-term lignite extraction on the western pit wall slope of the Bełchatów field and the salt dome’s stability conditions. This study offers a comprehensive approach to a complex geotechnical problem defined by large-scale, complex geometry, and geological conditions. The rock mass behavior and stress conditions are simulated in numerical modelling. The results of the presented analysis will be useful not only for present mining activities but also for future developments related to post-mining and recultivation plans.

Three Dimensional Numerical Analysis of Deformation and Stability of Zone II of Xiazanri Slope Deposit

2011 ◽  
Vol 90-93 ◽  
pp. 2372-2379
Author(s):  
Li Fang Zou ◽  
Wei Ya Xu ◽  
Chong Shi
Keyword(s):  
Large Scale ◽  
Failure Modes ◽  
Three Dimensional ◽  
Left Bank ◽  
Failure Characteristics ◽  
Deformation And Failure ◽  
Geological Conditions ◽  
Normal Water ◽  
Zone Ii ◽  
Very High

Xiazanri Slope is a large-scale deposit slope located at the left bank of Liyuan hydropower station in Southwest China. The construction of the water intake there will form a very high excavation slope. Possible failure modes are analyzed based on geological conditions. Numerical simulation is conducted in FLAC3D to obtain the deformation and failure characteristics of slope under excavation and normal water table conditions. Strength reduction method is used to obtain factor of safety. Results show the overall deposit is stable and attention should be paid to local parts.

scholarly journals Failure Characteristics and Stability Control of Bolt Support in Thick-Coal-Seam Roadway of Three Typical Coal Mines in China

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Zhe Xiang ◽  
Nong Zhang ◽  
Deyu Qian ◽  
Zhengzheng Xie ◽  
Chenghao Zhang ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mines ◽  
Stability Control ◽  
Western China ◽  
Thick Coal Seam ◽  
Failure Characteristics ◽  
Safety Control ◽  
Geological Conditions ◽  
Roadway Safety ◽  
Bolt Failure

Roadways in thick coal seams are widely distributed in China. However, due to the relatively developed cracks and brittleness of coal, the support failure of thick-coal-seam roadways frequently occurs. Therefore, the study of bolt failure characteristics and new anchoring technology is very important for the safety control of thick-coal-seam roadways. Based on field observations, the failure mechanism of selected roadway failures under distinct conditions at three representative coal mines in eastern and western China was analyzed. Recommendations are provided for roadway safety control. The results show that the strength and dimension of the anchoring structure in the coal roof of thick-coal-seam roadways are the decisive factors for the resistance of the roadway convergence and stress disturbance. The thick anchoring structure in the roof constructed by flexible long bolts can effectively solve the problem of support failure caused by insufficient support length of traditional rebar bolts under the condition of extra-thick coal roof and thick coal roof with weak interlayers. The concepts and techniques presented in the paper provide a reference for the design of roadway support under similar geological conditions and dynamic load.

scholarly journals Experimental analysis of control technology and deformation failure mechanism of inclined coal seam roadway using non-contact DIC technique

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xianyu Xiong ◽  
Jun Dai ◽  
Yibo Ouyang ◽  
Pan Shen
Keyword(s):  
Coal Seam ◽  
Failure Mechanism ◽  
Stability Control ◽  
Surrounding Rock ◽  
Image Correlation ◽  
Engineering Practice ◽  
Control Technology ◽  
Support Design ◽  
Deformation Control ◽  
Geological Conditions

AbstractThe deformation and failure forms of inclined coal seam roadway under the joint action of dip angle and various geological conditions are complex, and there is a lack of targeted support measures, which brings great problems to the stability control of roadway surrounding rock. In order to safely and economically mine inclined coal seams, taking the engineering geology of Shitanjing No. 2 mining area as the background, and the physical similarity model of right-angle trapezoidal roadway in inclined coal seam, in which the non-contact digital image correlation (DIC) technology and the stress sensor is employed to provide full-field displacement and stress measurements. The deformation control technology of the roadway surrounding rock was proposed, verified by numerical simulation and applied to engineering practice. The research results show that the stress and deformation failure of surrounding rock in low sidewall of roadway are greater than those in high sidewall, showing asymmetric characteristics, and the maximum stress concentration coefficients of roadway sidewall, roof and floor are 4.1, 3.4 and 2.8, respectively. A concept of roadway "cyclic failure" mechanism is proposed that is, the cyclic interaction of the two sidewalls, the sharp angles and roof aggravated the failure of roadway, resulting in the overall instability of roadway. The roadway sidewall is serious rib spalling, the roof is asymmetric "Beret" type caving arch failure, and the floor is slightly bulging. On this basis, the principle of roadway deformation control is revealed and asymmetric support design is adopted, and the deformation of roadway is controlled, which support scheme is effective.

scholarly journals Forecast changes in the geodynamic regime of geological environment during large-scale subsoil development

2021 ◽  
pp. 5-10
Author(s):  
M.B Nurpeisova ◽  
M.Zh Bitimbayev ◽  
K.B Rysbekov ◽  
Sh. Sh Bekbasarov
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Structural Features ◽  
Educational Process ◽  
Industrial Safety ◽  
Geological Environment ◽  
Mining Operations ◽  
Capital Costs ◽  
Study Results ◽  
Geological Conditions

Purpose. Developing the methods for forecasting changes in the geological environment based on integrated monitoring, which ensures industrial and environmental safety of Central Kazakhstan region. Methodology. Integrated approach was used in the work, including: study on mining and geological conditions, structural features of rocks and conducting mine surveying at mines on the basis of modern methods and means of geomonitoring developed by the authors. Findings. Methodology for integrated geodynamic monitoring system is developed. A new method of geodynamic polygon establishment is proposed. Study results were implemented at operating mining enterprises during implementation of projects Comprehensive monitoring of slow deformation processes of the earths surface during large-scale development of ore deposits in Central Kazakhstan and Development of innovative methods for forecasting and assessing the state of rock mass to prevent technogenic emergencies, and the results were used in the educational process of Satbayev University. Originality. As a result of the research work carried out, the following were created and introduced into production: - geodynamic polygon (GDP) of the area, established on the basis of the nodal method, combined with leveling, satellite and seismological points, allowing monitoring coverage of exploration and mining operations, as well as increasing efficiency of observations and reducing capital costs for mineral production; - developed constructions of permanent (ground and underground) forced centering points (FCP), which allow increasing productivity and observations accuracy; - method for photographing structural features of rock mass using a 3D laser scanner, which makes it possible to study elements of cracks occurrence and faults in rocks in sufficient detail; - composition of strengthening solution from mining waste to increase stability of disturbed sections of open cast benches was developed. The novelty of the developed methods and means is confirmed by RK patents for invention. Practical value. Obtained results can be used to improve the level of industrial safety at mines and minimize environmental risks caused by subsoil development.

Prince Henri d'Orleans (1867–1901): geographical and botanical exploration between inner Asia and southwest China

1978 ◽  
Vol 8 (4) ◽  
pp. 399-399
Author(s):  
WILLIAM GARDENER
Keyword(s):  
Southwest China ◽  
Western China ◽  
Left Bank ◽  
Inner Asia ◽  
Botanical Exploration ◽  
Western Yunnan ◽  
Westerly Direction ◽  
Chinese Province ◽  
The Right ◽  
North Western

Prince Henri d'Orleans, precluded by French law from serving his country in the profession of arms, had his attention turned early towards exploration. In 1889, accompanied by the experienced traveller Gabriel Bonvalet, he set out from Paris to reach Indo-China overland by way of Central Asia, Tibet and western and south western China. The journey made contributions in the problems of the whereabouts of Lap Nor and the configuration of the then unexplored northern plateau of Tibet; and in botany it produced some species new to science. The party reached Indo-China in 1890. In 1895, having organised an expedition better equipped for topographical survey and for investigations in the fields of natural history and ethnography, Prince Henri set out from Hanoi with the intention of exploring the Mekong through the Chinese province of Yunnan. After proceeding up the left bank of the Salween for a brief part of its course and then alternating between the right and left banks of the Mekong as far up as Tzeku, the party found it advisable to enter Tibet in a north westerly direction through the province of Chamdo and instead crossed the south eastern extremity of the country, the Zayul, by a difficult track which led them to the country of the Hkamti Shans in present day Upper Burma, and thence to India completing a journey of 2000 miles, "1500 of which had been previously untrodden" (Prince Henri). West of the Mekong, the journey established that the Salween, which some geographers had claimed took its rise in or near north western Yunnan, in fact rose well north in Tibet, and that, contrary to previous opinions, the principal headwater of the Irrawaddy rose no further north than latitude 28°30'. Botanical collections were confined to Yunnan, where the tracks permitted mule transport, and they produced a number of species new to science and extended the range of distribution of species already known.

In Situ Tests on Creep Behavior of Rock Mass with Joint or Shearing Zone in Foundation of Large-Scale Hydroelectric Projects

2004 ◽  
Vol 261-263 ◽  
pp. 1097-1102 ◽  
Author(s):  
Jian Liu ◽  
Xia Ting Feng ◽  
Xiu Li Ding ◽  
Huo Ming Zhou
Keyword(s):  
Rock Mass ◽  
Creep Behavior ◽  
Large Scale ◽  
Time Dependent ◽  
Three Gorges Project ◽  
Three Gorges ◽  
The Three Gorges ◽  
The Three Gorges Project

The time-dependent behavior of rock mass, which is generally governed by joints and shearing zones, is of great significance for engineering design and prediction of long-term deformation and stability. In situ creep test is a more effective method than laboratory test in characterizing the creep behavior of rock mass with joint or shearing zone due to the complexity of field conditions. A series of in situ creep tests on granite with joint at the shiplock area of the Three-Gorges Project and basalt with shearing zone at the right abutment of the Xiluodu Project were performed in this study. Based on the test results, the stress-displacement-time responses of the joints and basalt are analyzed, and their time-dependent constitutive model and model coefficients are given, which is crucial for the design to prevent the creep deformations of rock masses from causing the failure of the operation of the shiplock gate at the Three-Gorges Project and long-term stability of the Xiluodu arc dam.

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