scholarly journals Mechanisms of Rock Burst in Horizontal Section Mining of a Steeply Inclined Extra-Thick Coal Seam and Prevention Technology

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 6043
Author(s):  
Jinrong Cao ◽  
Linming Dou ◽  
Guangan Zhu ◽  
Jiang He ◽  
Shengchuan Wang ◽  
...  
Keyword(s):  
Distinct Element ◽  
Field Measurements ◽  
Field Studies ◽  
Static Stress ◽  
Dynamic Loads ◽  
Horizontal Section ◽  
Thick Coal Seam ◽  
Rock Bursts ◽  
Universal Distinct Element Code ◽  
Distinct Element Code

Rock bursts have recently become a serious problem in the horizontal section mining of steeply inclined extra-thick coal seams (SIETCSs). However, few studies have been carried out to investigate their mechanisms and prevention. In this study, numerical simulation and field measurements were carried out to investigate the mechanism of rock bursts in the horizontal section mining of an SIETCS. A Universal Distinct Element Code (UDEC) Trigon model was built, based on the Yaojie No.3 Coal Mine, and calibrated through laboratory tests and RQD methods. The results demonstrate that the coal in the elastic zone around the roof is in a high static stress state, due to the asymmetric clamping and squeezing of the roof and floor. Strong dynamic loads are formed by breakage of the roof and the failure of multiple hinged beam structures during the evolution process of the overlying strata. Rock bursts occur on the roof side when the superimposition of the static stress σs and stress increment σd induced by such dynamic loads is greater than the critical stress σmin of the coal and rock. We propose a technical prevention scheme for the considered mine. Field studies suggest that the proposed technology can effectively prevent and control rock bursts in the horizontal section mining of SIETCSs.

scholarly journals Failure of an under-dip shale slope and its response under excavation conditions

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Bin Li ◽  
◽  
Yanzhi Zhu ◽  
Fuzhou Qi ◽  
Zhenxia Yuan ◽  
...  
Keyword(s):  
Progressive Failure ◽  
Distinct Element ◽  
Failure Process ◽  
Field Measurements ◽  
Deformation Characteristics ◽  
Cut Slope ◽  
Site Investigations ◽  
Universal Distinct Element Code ◽  
Distinct Element Code

A landslide has occurred in the cut slope located in Chongqing Xi railway station. This slope belongs to a shale under-dip slope and has a complex failure mechanism. Some on-site investigations have been made to explore the deformation characteristics of this slope, and structural geology analyses and outcomes of geological investigations in situ are firstly described. The progressive failure process of the slope during unloading excavation has also been simulated by the Universal Distinct Element Code (UDEC). The obtained deformation characteristics of the slope have proven to well match the field measurements, which verifies the practicability of the UDEC model.

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.

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 Mechanism of Coal Bursts Induced by Horizontal Section Mining of Steeply Inclined Coal Seams and Application of Microseismic Multiparameter Monitoring in Early Warning

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Sheng-Chuan Wang ◽  
Lin-Ming Dou ◽  
Zheng-Yi Wang ◽  
Jin-Zheng Bai ◽  
Yan-Jiang Chai
Keyword(s):  
Seismic Tomography ◽  
High Sensitivity ◽  
Propagation Distance ◽  
Static Stress ◽  
Dynamic Loads ◽  
Coal Seams ◽  
Horizontal Section ◽  
Static Loads ◽  
Coal Bursts ◽  
Precursory Information

Coal bursts occurring in steeply inclined coal seams (SICSs) are increasingly severe. To solve this problem, a mechanical model for the distribution of static stress on coal-rock masses along panels and the distribution of dynamic load induced by the breakage of thick and hard roofs with propagation distance was established. The stress characteristics after a superposition of dynamic and static loads on the roof and floor roadways (Rr and Rf) were determined. In addition, precursory information characteristics and index sensitivities of four indices for dynamic loads and the CT index for static loads based on seismic tomography were separately analyzed. The monitoring and warning indices for SICSs and flat seams were compared. The results showed that the static stress of Rr was significantly higher than that of Rf, which provided a basis for the stress-triggering coal burst behaviors. Three indices for dynamic loads and seismic tomography results exhibited remarkable precursory information and high sensitivity. However, the performance of lack of shock index is poor. The continuous anomaly and the contradiction of indices at Rr and Rf can be considered as precursory information for predicting coal bursts.

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 Numerical Investigation into Evolution of Crack and Stress in Residual Coal Pillars under the Influence of Longwall Mining of the Adjacent Underlying Coal Seam

2019 ◽  
Vol 2019 ◽  
pp. 1-18
Author(s):  
Xin Wang ◽  
Yuechao Wu ◽  
Xuehua Li ◽  
Shun Liang
Keyword(s):  
Coal Seam ◽  
Longwall Mining ◽  
Distinct Element ◽  
Movement Characteristics ◽  
Universal Distinct Element Code ◽  
Voronoi Method ◽  
Mining Safety ◽  
Distinct Element Code ◽  
Coal Pillars ◽  
Residual Coal

Longwall mining of the adjacent coal seam with the presence of residual coal pillars overlying the seam can result in abnormal strata pressure and severe overburden failure, which poses a significant threat to mining safety. The threat is mainly manifested in the form of intense coal or rock burst and hazardous interconnection between gobs. This study employed the universal distinct element code (UDEC) to investigate the microscopic failure mechanism of the overlying residual coal pillars under the influence of longwall mining of an adjacent underlying coal seam in Yuanbaowan coal mine, China. Using the Voronoi method, we innovatively visualized the evolution of cracks in residual pillars, revealed the mechanism behind the failure of pillars, and explored the evolution and distribution of abutment stress. Also, strata movement characteristics during underlying panel extraction have been surveyed. Based on the modeling results, effective measures are proposed to ensure safe mining under residual coal pillars. This study might provide a certain reference for safe extraction of multiple seams in Datong Coalfield, China, and also in the central and western Appalachian Basin, United States, where many mining activities are carried out under residual pillars.

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