scholarly journals Numerical Analyses on Deformation and Failure Characteristics of Surrounding Rock of Gob-Side Entry Retention by Roof Cutting

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Qunying Wu ◽  
Binhui Liu ◽  
Jun Yang ◽  
Yajun Wang ◽  
Kuikui Chen ◽  
...  
Keyword(s):  
Large Scale ◽  
Distinct Element ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Failure Characteristics ◽  
Deformation And Failure ◽  
Temporary Support ◽  
Universal Distinct Element Code ◽  
Distinct Element Code ◽  
Borehole Televiewer

Universal distinct element code (UDEC) is a simulation software based on the discrete element method, widely used in geotechnical mining. However, in the UDEC, when simulating large-scale excavation, the subsidence of the fractured zone is almost equal to the mining height, which makes the deformation value calculated in the study of gob-side entry retention too large. To solve this problem, in this paper, the double-yield constitutive model is applied to the whole caving zone to analyze the deformation and failure characteristics of surrounding rock along gob-side entry retaining by roof cutting. The results of the simulation are in good agreement with the result of drilling peeking (drilling observation by borehole televiewer) and field condition (observation and measurement in the field). Finally, by using this numerical method, the effects of roadway width, temporary support, and coal side support on the failure of the roof and the arc coal side are studied.

Research on Mining Technological Parameters of 7# Thin Coal Seam in Liuquan Mine

2012 ◽  
Vol 629 ◽  
pp. 937-942
Author(s):  
Dong Sheng Zhang ◽  
Xu Feng Wang ◽  
Yang Zhang ◽  
Jin Liang Wang
Keyword(s):  
Coal Seam ◽  
Distinct Element ◽  
Horizontal Displacement ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Technological Parameters ◽  
Thin Coal Seam ◽  
Geological Conditions ◽  
Universal Distinct Element Code ◽  
Distinct Element Code

Aimed at the specific geological conditions of 7# thin coal seam in Liuquan Mine, this paper used the methods of numerical calculation and theoretical analysis to determine the reasonable technological parameters of high-grade conventional mining face. The numerical simulation software of UDEC (Universal Distinct Element Code) was used to contrast and analyse the characteristics of surrounding rock stress distribution and overlying rock horizontal displacement under the condition of different length of coalface, then it was indicated that the surrounding rock deformation was less when length of coalface was 110 m which was advantageous for roof control; according to the conditions of roof and floor, the roof support strength was being calculated systematically to determine the row space of props being 700×1200 mm; the main equipments of coalface was assorted, and reasonable work manner in coalface and gob processing measure was put forward, which provided guidance for efficient mining in thin coal seam.

scholarly journals Buckling Failure Mechanism of a Rock Dam Foundation Fractured by Gentle Through-Going and Steep Structural Discontinuities

2020 ◽  
Vol 12 (13) ◽  
pp. 5426
Author(s):  
Donghui Chen ◽  
Huie Chen ◽  
Wen Zhang ◽  
Chun Tan ◽  
Zhifa Ma ◽  
...  
Keyword(s):  
Numerical Method ◽  
Failure Mechanism ◽  
Shear Failure ◽  
Distinct Element ◽  
Mechanism Analysis ◽  
Rock Masses ◽  
Dam Foundation ◽  
Deformation Features ◽  
Universal Distinct Element Code ◽  
Distinct Element Code

The failure mechanism analysis of dam foundations is key for designing hydropower stations. This study analyses the rock masses in a sluice section, which is an important part of the main dam of the Datengxia Hydropower Station currently built in China. The stability of the sluice rock masses is predominantly affected by gentle through-going soft interlayers and steep structural fractures. Its foundation failure mechanism is investigated by means of a numerical method, i.e., Universal Distinct Element Code (UDEC) and the geomechanical model method. The modeling principle and process, and results for the rock dam foundation are introduced and generated by using the abovementioned two methods. The results indicate that the failure mechanism of the foundation rock masses, as characterized by gentle through-going and steep structural discontinuities, is not a conventional type of shear failure mechanism but a buckling one. This type of failure mechanism is verified by analyzing the deformation features resulting from the overloading of both methods and strength reduction of the numerical method.

scholarly journals Formation, breaching and flood consequences of a landslide dam near Bujumbura, Burundi

2018 ◽  
Vol 18 (7) ◽  
pp. 1867-1890 ◽  
Author(s):  
Léonidas Nibigira ◽  
Hans-Balder Havenith ◽  
Pierre Archambeau ◽  
Benjamin Dewals
Keyword(s):  
Distinct Element ◽  
Mass Movement ◽  
Geophysical Methods ◽  
Landslide Dam ◽  
Propagation Time ◽  
Universal Distinct Element Code ◽  
Landslide Process ◽  
Distinct Element Code ◽  
Set Up ◽  
Flood Intensity

Abstract. This paper investigates the possible formation of a landslide dam on the Kanyosha River near Bujumbura, the capital of Burundi, as well as the interplay between the breaching of this landslide dam and the flooding along the river. We present an end-to-end analysis, ranging from the origin of the landslide up to the computation of flood waves induced by the dam breaching. The study includes three main steps. First, the mass movement site was investigated with various geophysical methods that allowed us to build a general 3-D model and detailed 2-D sections of the landslide. Second, this model was used for dynamic landslide process modelling with the Universal Distinct Element Code. The results showed that a 15 m high landslide dam may form on the river. Finally, a 2-D hydraulic model was set up to find out the consequences of the breaching of the landslide dam on flooding along the river, especially in an urban area located downstream. Based on 2-D maps of maximum water depth, flow velocity and wave propagation time, the results highlight that neglecting the influence of such landslide dams leads to substantial underestimation of flood intensity in the downstream area.

Optimizing Method of Main Caverns in Large Underground Water-Sealed Storage Caverns

2021 ◽  
Author(s):  
Yang An ◽  
E-chuan Yan ◽  
Xing-ming Li ◽  
Shao-ping Huang
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Distinct Element ◽  
Strength Criterion ◽  
Axial Direction ◽  
Optimization Method ◽  
Underground Water ◽  
Land Resource ◽  
Maximum Displacement ◽  
Distinct Element Code

Abstract As a main method of petroleum strategic reserve in China, underground water-sealed storage cavern owns lots of outstanding advantages, such as low operating costs, high safety, and land resource conservation. Main caverns are important structure in underground project and the layout parameters and excavation scheme will have significant impact on overall project quality. The optimization method of main cavern layout and excavation scheme was put forward by a proposed large-scale underground water-sealed cavern project in China. First, based on field survey results, the Hoek-Brown strength criterion combined with rock mass quality Q classification system was used to estimate the equivalent mechanical parameters of rock mass. Second, the numerical experiments were carried out by relying on 3 Dimensions Distinct Element Code (3DEC). The discontinuous medium model was adopted, and displacements of key points, maximum displacement values and volume of the plastic zone were used as evaluation indicators. Axial direction, buried depth, spacing and excavation scheme of main caverns have been optimized. Results showed that axial direction should adopt NW325°, buried depth of cavern roof should locate at -100m, and distance between adjacent main caverns should be 1.5 times the span (36m). The “jump excavation” mode was recommended in construction. That is, the caverns on both sides should be excavated first, and the middle cavern should be excavated later. This mode could effectively reduce the interaction effect between caverns. This method has the characteristics of easy data acquisition and strong operability. It could be used to guide design and construction of similar projects . As a main method of petroleum strategic reserve in China, underground water-sealed storage cavern owns lots of outstanding advantages, such as low operating costs, high safety, and land resource conservation. Main caverns are important structure in underground project and the layout parameters and excavation scheme will have significant impact on overall project quality. The optimization method of main cavern layout and excavation scheme was put forward by a proposed large-scale underground water-sealed cavern project in China. First, based on field survey results, the Hoek-Brown strength criterion combined with rock mass quality Q classification system was used to estimate the equivalent mechanical parameters of rock mass. Second, the numerical experiments were carried out by relying on 3 Dimensions Distinct Element Code (3DEC). The discontinuous medium model was adopted, and displacements of key points, maximum displacement values and volume of the plastic zone were used as evaluation indicators. Axial direction, buried depth, spacing and excavation scheme of main caverns have been optimized. Results showed that axial direction should adopt NW325°, buried depth of cavern roof should locate at -100m, and distance between adjacent main caverns should be 1.5 times the span (36m). The “jump excavation” mode was recommended in construction. That is, the caverns on both sides should be excavated first, and the middle cavern should be excavated later. This mode could effectively reduce the interaction effect between caverns. This method has the characteristics of easy data acquisition and strong operability. It could be used to guide design and construction of 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 Formation, breaching and flood consequences of a landslide dam near Bujumbura, Burundi

2017 ◽  
Author(s):  
Léonidas Nibigira ◽  
Hans-Balder Havenith ◽  
Pierre Archambeau ◽  
Benjamin Dewals
Keyword(s):  
Flood Hazard ◽  
Distinct Element ◽  
Mass Movement ◽  
Geophysical Methods ◽  
Landslide Dam ◽  
Propagation Time ◽  
Universal Distinct Element Code ◽  
Landslide Process ◽  
Maximum Water ◽  
Distinct Element Code

Abstract. This paper investigated the possible formation of a landslide dam on the Kanyosha River near Bujumbura, the capital of Burundi, as well as the interplay between the breaching of this landslide dam and the flooding along the river. We present an end-to-end analysis, ranging from the origin of the landslide up to the computation of flood waves induced by the dam breaching. The study includes three main steps. First, the mass movement site was investigated with various geophysical methods that allowed us to build a general 3D model and detailed 2D sections of the landslide. Second, this model was used for dynamic landslide process modelling with the Universal Distinct Element Code. The results showed that a fifteen-meter-high landslide dam may form on the river. Finally, a 2D hydraulic model was setup to find out the consequences of the breaching of the landslide dam on flooding along the river, especially in an urban area located downstream. Based on 2D maps of maximum water depth, flow velocity and wave propagation time, the results highlight that neglecting the influence of such landslide dams leads to substantial underestimation of flood hazard in the downstream area.

Preliminary Study on the Progressive Failure of a Layered Rock Slope under Explosions

2006 ◽  
Vol 306-308 ◽  
pp. 1461-1466 ◽  
Author(s):  
Y.Q. Liu ◽  
Hai Bo Li ◽  
H.C. Dai ◽  
Jun Ru Li ◽  
Qing Chun Zhou
Keyword(s):  
Critical Point ◽  
Rock Slope ◽  
Progressive Failure ◽  
Distinct Element ◽  
Failure Process ◽  
Two Dimensional ◽  
Layered Rock ◽  
Universal Distinct Element Code ◽  
Preliminary Study ◽  
Distinct Element Code

The progressive failure process of a layer rock slope under explosions is simulated using two-dimensional Universal Distinct Element Code (UDEC). It is shown that the failure process of the slope can be divided into three phases, the formation and growth of local failure area as well as coalescence of sliding plane. In addition, the displacement components of a critical point of the slope are also suggested to be a progressive process.

scholarly journals Deformation and Failure Mechanism of Surrounding Rock in Mining-Influenced Roadway and the Control Technology

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Jicheng Feng ◽  
Shuaifeng Yin ◽  
Zhiheng Cheng ◽  
Jianjun Shi ◽  
Haoyu Shi ◽  
...  
Keyword(s):  
Plastic Zone ◽  
Failure Mechanism ◽  
Principal Stress ◽  
Pressure Ratio ◽  
Confining Pressure ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Morphologic Change ◽  
Deformation And Failure ◽  
Implicit Equation

Aiming at the problem of surrounding rock deformation and failure of mining roadway and its control, a mechanical model of the circular roadway under the mining environment is established, and the implicit equation of the plastic zone boundary is derived. By analyzing the morphologic evolution law of the surrounding rock plastic zone in the mining roadway, the key factors affecting the morphologic change of the plastic zone are obtained, that is, the magnitude and direction of principal stress. The influence law of the magnitude and direction of principal stress on the plastic zone of the mining roadway is analyzed by using numerical simulation software, and the deformation and failure mechanism of surrounding rock of the mining roadway is revealed. The results showed that the size and morphology of the plastic zone were closely related to the confining pressure ratio (η). Taking the boundary of η valuing 1, the larger or smaller η value was, the more serious the deformation and failure of surrounding rock would be; the morphology of the plastic zone changed with the deflection of the principal stress, with the location of the maximum plastic zone influenced by the principal stress direction. For the surrounding rock control in the mining-influenced roadway, it is advised to take the following methods: firstly, it is necessary to consider how to reduce or remove the influence of mining on surrounding rock, improve the stress environment of surrounding rock, and reduce the failure depth of the plastic zone, so as to better maintain the roadway. Secondly, in view of the deformation and failure characteristics of the mining roadway, the fractional support method of “yielding first and then resisting” should be adopted, which applies the cable supplement support after mining instead of the one-off high-strength support during roadway excavation, so as to control the malignant expansion of the surrounding rock plastic zone and prevent roof falling accidents.

scholarly journals Deformation and Failure Characteristics of the Roof in an Unsupported Area during Rapid Driving of Coal Roadway

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Sen Yang ◽  
Xinzhu Hua ◽  
Xiao Liu ◽  
Enqian Wang ◽  
Chen Li
Keyword(s):  
Thin Plate ◽  
Simulation Software ◽  
Failure Characteristics ◽  
Deformation And Failure ◽  
Bending Deformation ◽  
Coal Roadway ◽  
Driving Speed ◽  
Support Force ◽  
Supporting Force ◽  
Influence Degree

In order to study the deflection and failure characteristics of the goaf roof, a mechanical model of the goaf thin plate is established and the deflection expression of the goaf roof is obtained. The results show the following: (1) under the action of single factor, the roof deflection is more sensitive to the interaction of unsupported roof distance and load, but less sensitive to the support force. (2) The influence degree of each factor on the deflection of the thin plate in the unsupported top area is as follows: unsupported roof distance and load interaction > unsupported roof distance and supporting force > supporting force and load. (3) The roof bending deformation is slow when the unsupported roof distance is within 0–2.3 m. When the vacant distance of the roof is more than 2.3 m, the bending deformation of the roof is accelerated. Using FLAC3D numerical simulation software, the distribution of vertical stress and displacement under different space distances is analyzed and the reasonable space distance is 2.0 m. Through the application of 150802 machine roadway in Liuzhuang coal mine, the driving speed of the coal roadway is improved and the monthly footage of coal roadway reaches 506 m.

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