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

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.

2012 ◽  
Vol 629 ◽  
pp. 937-942
Author(s):  
Dong Sheng Zhang ◽  
Xu Feng Wang ◽  
Yang Zhang ◽  
Jin Liang Wang

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.


2020 ◽  
Vol 12 (13) ◽  
pp. 5426
Author(s):  
Donghui Chen ◽  
Huie Chen ◽  
Wen Zhang ◽  
Chun Tan ◽  
Zhifa Ma ◽  
...  

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.


2018 ◽  
Vol 18 (7) ◽  
pp. 1867-1890 ◽  
Author(s):  
Léonidas Nibigira ◽  
Hans-Balder Havenith ◽  
Pierre Archambeau ◽  
Benjamin Dewals

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.


2017 ◽  
Author(s):  
Léonidas Nibigira ◽  
Hans-Balder Havenith ◽  
Pierre Archambeau ◽  
Benjamin Dewals

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.


2006 ◽  
Vol 306-308 ◽  
pp. 1461-1466 ◽  
Author(s):  
Y.Q. Liu ◽  
Hai Bo Li ◽  
H.C. Dai ◽  
Jun Ru Li ◽  
Qing Chun Zhou

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.


2012 ◽  
Vol 256-259 ◽  
pp. 547-551 ◽  
Author(s):  
Yong Xu ◽  
Wei Hong Peng

Considering the seepage stress coupling of fractured rock mass, the multiple holes grouting problems were simulated to analyse the spread regularity by Universal Distinct Element Code(UDEC).The results show that the correlation between grouting pressure and the diffusion distance is positive, whereas the correlation between ground stress and diffusion distance is negative; With the raising of grouting holes, the diffusion distance is increasing and becoming more uniform in all directions, and the grout pressure and saturation is falling and attenuation amplitude is decreasing along the direction of grout diffusion; With the increasing of fracture aperture, the grout diffusion distance is increasing, and the grout pressure and saturation attenuation amplitude is decreasing along the direction of grout diffusion.


2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Qunying Wu ◽  
Binhui Liu ◽  
Jun Yang ◽  
Yajun Wang ◽  
Kuikui Chen ◽  
...  

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.


2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Bin Li ◽  
◽  
Yanzhi Zhu ◽  
Fuzhou Qi ◽  
Zhenxia Yuan ◽  
...  

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.


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