scholarly journals Mechanical Analysis of the Failure Characteristics of Stope Floor Induced by Mining and Confined Aquifer

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Zhiguo Lu ◽  
Wenjun Ju ◽  
Xiwen Yin ◽  
Zhuoyue Sun ◽  
Fengda Zhang ◽  
...  
Keyword(s):  
Shear Stress ◽  
Stress Gradient ◽  
Absolute Error ◽  
Horizontal Stress ◽  
Vertical Stress ◽  
Confined Aquifer ◽  
Solid Coal ◽  
Floor Failure ◽  
Failure Depth

Mining above confined aquifer has become an important task for water inrush prevention in China. To study the failure characteristics of stope floor along the strike, a mechanical model under combined action of mining and confined aquifer was constructed, and the distribution of vertical stress, horizontal stress, and shear stress was obtained. Based on the Mohr–Coulomb criterion, the failure range of the floor is determined and verified by the in situ test. The results indicate the following. (1) Both vertical stress and horizontal stress in the stope floor take the junction of stress increasing area and stress decreasing area as the dividing line, forming two groups of “convex arches” at the solid coal side and the goaf side, respectively. (2) The vertical stress gradient in the solid coal side is significantly higher than that in the goaf side, while the horizontal stress gradient in the solid coal side is similar to that in the goaf side. The shear stress distribution is divided into three regions by the boundary between positive and negative shear stress, which makes the stope floor in this area to show compression shear or tension shear failure. (3) According to the in situ test, the maximum floor failure depth of 41503 working face is 11.38 m, which is quite close to the theoretical calculation result of 9.68 m. (4) Applying the mechanical model to five other coal mines with different mining conditions and stress states, the maximum absolute error between the measured and theoretical values of floor failure depth is 1.1 m, the average absolute error is 0.8 m, the maximum relative error is 8.2%, and the average relative error is 6.5%. The study provides a certain mechanical basis and reference for the floor failure mechanism induced by mining and confined aquifer.

scholarly journals Modulating wall shear stress gradient via equilateral triangular channel for in situ cellular adhesion assay

2016 ◽  
Vol 10 (5) ◽  
pp. 054119 ◽  
Author(s):  
Hyung Woo Kim ◽  
Seonjin Han ◽  
Wonkyoung Kim ◽  
Jiwon Lim ◽  
Dong Sung Kim
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Stress Gradient ◽  
Cellular Adhesion ◽  
Adhesion Assay ◽  
Triangular Channel ◽  
Wall Shear Stress Gradient ◽  
Shear Stress Gradient ◽  
Wall Shear

scholarly journals In Situ Stress and Stress Regime in the Onshore Part of the Northeast Java Basin

2021 ◽  
Vol 44 (2) ◽  
pp. 95-105
Author(s):  
Agus M. Ramdhan
Keyword(s):  
Petroleum Industry ◽  
Horizontal Stress ◽  
In Situ Stress ◽  
Vertical Stress ◽  
Stress Regime ◽  
Severe Erosion ◽  
Tectonically Active ◽  
Minimum Horizontal Stress ◽  
Maximum Horizontal Stress

In situ stress is importance in the petroleum industry because it will significantly enhance our understanding of present-day deformation in a sedimentary basin. The Northeast Java Basin is an example of a tectonically active basin in Indonesia. However, the in situ stress in this basin is still little known. This study attempts to analyze the regional in situ stress (i.e., vertical stress, minimum and maximum horizontal stresses) magnitude and orientation, and stress regime in the onshore part of the Northeast Java Basin based on twelve wells data, consist of density log, direct/indirect pressure test, and leak-off test (LOT) data. The magnitude of vertical (  and minimum horizontal (  stresses were determined using density log and LOT data, respectively. Meanwhile, the orientation of maximum horizontal stress  (  was determined using image log data, while its magnitude was determined based on pore pressure, mudweight, and the vertical and minimum horizontal stresses. The stress regime was simply analyzed based on the magnitude of in situ stress using Anderson’s faulting theory. The results show that the vertical stress ( ) in wells that experienced less erosion can be determined using the following equation: , where  is in psi, and z is in ft. However, wells that experienced severe erosion have vertical stress gradients higher than one psi/ft ( . The minimum horizontal stress ( ) in the hydrostatic zone can be estimated as, while in the overpressured zone, . The maximum horizontal stress ( ) in the shallow and deep hydrostatic zones can be estimated using equations: and , respectively. While in the overpressured zone, . The orientation of  is ~NE-SW, with a strike-slip faulting stress regime.

scholarly journals The Effects of Backfill Mining on Strata Movement Rule and Water Inrush: A Case Study

Processes ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 66 ◽  
Author(s):  
Jian Hao ◽  
Yongkui Shi ◽  
Jiahui Lin ◽  
Xin Wang ◽  
Hongchun Xia
Keyword(s):  
Longwall Mining ◽  
Water Inrush ◽  
Vertical Stress ◽  
Strata Movement ◽  
Ground Pressure ◽  
In Situ Investigation ◽  
Floor Failure ◽  
Backfill Mining ◽  
Failure Depth

Backfill mining is widely used to control strata movement and improve the stress environment in China’s coal mines. In the present study, the effects of backfill mining on strata movement and water inrush were studied based on a case study conducted in Caozhuang Coal Mine. The in-situ investigation measured abutment pressure distribution (APD), roof floor displacement (RFD), and vertical stress in the backfill area. Results are as follows: (i) The range and peak of APD, RFD, and vertical stress in the backfill area are smaller than in traditional longwall mining with the caving method. (ii) Backfill mining could change the movement form and amplitude of overburden and improve the ground pressure environment. (iii) Floor failure depth (FFD) is much smaller in backfill mining. Backfill mining can be an effective method for floor water inrush prevention.

Numerical Analysis of Widened Embankments with Geogrid Reinforcement

2012 ◽  
Vol 256-259 ◽  
pp. 2004-2008
Author(s):  
Min Yong Chen ◽  
Yu Liu ◽  
Hai Li Shi ◽  
Rui Chen ◽  
Bing Xiang Yuan
Keyword(s):  
Shear Stress ◽  
Numerical Analysis ◽  
Horizontal Stress ◽  
Vertical Stress ◽  
Stress Redistribution ◽  
Small Decrease ◽  
Geogrid Reinforcement ◽  
Layer Number

The mechanism of geogrid reinforcement in an embankment widening project was investigated in this study using numerical analysis. It was found that the geogrid reinforcement mainly affects the new embankment by decreasing settlement slightly and restraining the horizontal outward displacement effectively. This effect of geogrid reinforcement on embankment deformations is due to the stress redistribution in the new embankment and in the subsoil caused by geogrid reinforcement. The inclusion of geogrid reinforcement produces a small decrease in vertical stress in the new embankment and leads to a relatively larger increase in horizontal stress in the subsoil, thereby decreasing the shear stress of the subsoil. The effect of geogrid reinforcement on the new embankment and subsoil increases with the increasing geogrid layer number.

scholarly journals Numerical Simulation of Empty-Hole Effect during Parallel-Hole Cutting under Different In Situ Stress Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zhengyu Wu ◽  
Dayou Luo ◽  
Feng Chen ◽  
Wulin Huang
Keyword(s):  
Stress Field ◽  
Horizontal Stress ◽  
In Situ Stress ◽  
Vertical Stress ◽  
Stress Conditions ◽  
Deep Mining ◽  
In Situ Stress Field ◽  
Hole Effect ◽  
Parallel Hole

With the progress of deep mining in mine exploitation, the effect of the in situ stress field plays a more and more significant and crucial role in rock blasting. To uncover the impact of in situ stress field on empty-hole effect during parallel-hole cutting, the distribution and the trend of changes in dynamic stress around empty hole during blasting under different in situ stress conditions are simulated based on the basic model for parallel-hole cutting using 3D finite element analysis software ANSYS/LS-DYNA and implicit-explicit analysis method. Subsequently, the law of variation in the empty-hole effect under different in situ stress conditions is determined, and the effects of horizontal and vertical stress fields are analyzed in detail. The simulation results show that the overall increase in in situ stress can facilitate compressive failure and inhibit tensile failure in the rock mass around an empty hole during blasting. When empty holes are arranged horizontally, the effect of the vertical stress field is consistent with that of the in situ stress field, while the effect of the horizontal stress field is opposite to that of the in situ stress field. With the increased stress, the inhibitive effect of the vertical stress field on tensile stress around an empty hole is remarkably stronger than that of the horizontal stress field. Finally, the numerically simulated results are verified by the theoretical calculation. This study can provide new insight and a simple but accurate numerical simulation method to investigate how the in situ stress field affects the empty-hole effect, especially in deep mining.

scholarly journals Investigation on the CBM Extraction Techniques in the Broken-Soft and Low-Permeability Coal Seams in Zhaozhuang Coalmine

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Zhaoying Chen ◽  
Xuehai Fu ◽  
Guofu Li ◽  
Jian Shen ◽  
Qingling Tian ◽  
...  
Keyword(s):  
Coal Seam ◽  
Hydraulic Fracturing ◽  
Coalbed Methane ◽  
Research Result ◽  
Horizontal Stress ◽  
Gas Production ◽  
Vertical Stress ◽  
Low Permeability ◽  
Coal Seams

To enhance the coalbed methane (CBM) extraction in broken-soft coal seams, a method of drilling a horizontal well along the roof to hydraulically fracture the coal seam is studied (i.e., HWR-HFC method). We first tested the physical and mechanical properties of the broken-soft and low-permeability (BSLP) coal resourced from Zhaozhuang coalmine. Afterward, the in situ hydraulic fracturing test was conducted in the No. 3 coal seam of Zhaozhuang coalmine. The results show that (1) the top part of the coal seam is fractured coal, and the bottom is fragmented-mylonitic coal with a firmness coefficient value of less than 1.0. (2) In the hydraulic fracturing test of the layered rock-coal specimens in laboratory, the through-type vertical fractures are usually formed if the applied vertical stress is the maximum principal stress and is greater than 4 MPa compared with the maximum horizontal stress. However, horizontal fractures always developed when horizontal stress is the maximum or it is less than 4 MPa compared with vertical stress. (3) The in situ HWR-HFC hydraulic fracturing tests show that the detected maximum daily gas production is 11,000 m3, and the average gas production is about 7000 m3 per day. This implies that the CBM extraction using this method is increased by 50%~100% compared with traditional hydraulic fracturing in BSLP coal seams. The research result could give an indication of CBM developing in the broken-soft and low-permeability coal seams.

scholarly journals A multifactor coupling prediction model for the failure depth of floor rocks in fully mechanized caving mining: a numerical and in situ study

2019 ◽  
Vol 6 (8) ◽  
pp. 190528
Author(s):  
Yulong Jiang ◽  
Tingting Cai ◽  
Xiaoqiang Zhang
Keyword(s):  
Coal Seam ◽  
Prediction Model ◽  
Shanxi Province ◽  
Burial Depth ◽  
Floor Failure ◽  
Face Length ◽  
Mining Face ◽  
Failure Depth ◽  
Multifactor Coupling

To study the mining-induced failure depth of floor rocks in a fully mechanized mining caving field affected by different coal seam pitches, mining face lengths, burial depths and aquifer water pressures, multifactor-coupled orthogonal numerical tests on the failure depth of floor rocks were conducted. The numerical results show that the failure depth of floor rocks increases with increasing mining face length, coal seam pitch and burial depth. According to the relationship between failure depth and these impact factors, a multifactor-coupled prediction model for the failure depth of floor rocks was established. In addition, the in situ measurement of the failure depth of floor rocks in the Yitang Coal Mine in Huoxi coal field in Shanxi Province, China, was performed, and the in situ failure depths of floor rocks in the 100 502 (80 m) and 100 502 (180 m) mining faces were approximately 12.50–14.65 m and 17.50–19.20 m, in good agreement with the results of the multifactor prediction model. Furthermore, the sensitivity of each impact factor in the prediction model of the floor failure depth was further analysed by F -test and range analysis, and the impact order of studied factors on the floor failure depth is coal seam pitch > mining face length > burial depth > aquifer water pressure.

Floor Destruction Characteristic Study of Confined Water Effected by Mining Conditions

2012 ◽  
Vol 619 ◽  
pp. 253-258
Author(s):  
Lu Bin He ◽  
Bo Hou
Keyword(s):  
Water Inrush ◽  
Arbitrary Point ◽  
Base Plate ◽  
Horizontal Stress ◽  
Bottom Plate ◽  
The Sun ◽  
Confined Water ◽  
Infinite Body ◽  
Floor Failure ◽  
Failure Depth

Combined with Huaibei Mining Group 1028 Face of the Sun Tong mine site conditions,elasticity in the plane semi-infinite body established by the base plate of a mechanical model in the triangle strip load was used. The bottom plate of arbitrary point in the state of stress was analysised,and calculation formula of the horizontal stress,vertical stress and shear stress.was deduced.Based on elastic-plastic theory for solving the floor failure depth calculation of the floor limit conflict, the size of the water inrush combined with the Sun Tong mine 10 coal aquifer water inrush stress was analysised.The results of theoretical analysis of this article has some guidance, for the site management of the Sun Tong mine and has some reference for similar conditions.

scholarly journals Analysis of the Mechanical Response of Asphalt Pavement Under Water-Stress Coupling

2021 ◽  
Author(s):  
Kun Wang ◽  
Mingjun Wu ◽  
Peng Hu ◽  
Baoqun Wang
Keyword(s):  
Shear Stress ◽  
Mechanical Response ◽  
Pore Water Pressure ◽  
Asphalt Pavement ◽  
Water Pressure ◽  
Horizontal Stress ◽  
Vertical Stress ◽  
Shear Stresses ◽  
Vehicle Load ◽  
Asphalt Concrete Pavement

In order to study the mechanism of water damage of an asphalt pavement, the FLAC3D program was adopted to model and analyze the mechanical response of a saturated asphalt pavement under instantaneous vehicle load. The results show that the horizontal stress, vertical stress and shear stress of an asphalt concrete pavement increase with the increase of instantaneous load. The surfaces of asphalt pavement structural layers are most vulnerable to damage. The horizontal stress, vertical stress and shear stress decrease sharply with the instantaneous dynamic load decreasing to zero. The horizontal stress reaches maximum value at the interface between the base and the large stone porous mixture (LSPM) layer, while the maximum vertical and shear stresses occur on the surface layer of the saturated asphalt pavement. The deformation decreases almost linearly from the surface of the asphalt pavement to the subgrade, and the pore water pressure was little influenced by the transient load.

scholarly journals In Situ Stress and Stress Regime in the Onshore Part of the Northeast Java Basin

2021 ◽  
Vol 44 (2) ◽  
pp. 83-95
Author(s):  
Agus M. Ramdhan
Keyword(s):  
Petroleum Industry ◽  
Horizontal Stress ◽  
In Situ Stress ◽  
Vertical Stress ◽  
Stress Regime ◽  
Severe Erosion ◽  
Tectonically Active ◽  
Minimum Horizontal Stress ◽  
Maximum Horizontal Stress

In situ stress is importance in the petroleum industry because it will significantly enhance our understanding of present-day deformation in a sedimentary basin. The Northeast Java Basin is an example of a tectonically active basin in Indonesia. However, the in situ stress in this basin is still little known. This study attempts to analyze the regional in situ stress (i.e., vertical stress, minimum and maximum horizontal stresses) magnitude and orientation, and stress regime in the onshore part of the Northeast Java Basin based on twelve wells data, consist of density log, direct/indirect pressure test, and leak-off test (LOT) data. The magnitude of vertical (  and minimum horizontal (  stresses were determined using density log and LOT data, respectively. Meanwhile, the orientation of maximum horizontal stress  (  was determined using image log data, while its magnitude was determined based on pore pressure, mudweight, and the vertical and minimum horizontal stresses. The stress regime was simply analyzed based on the magnitude of in situ stress using Anderson’s faulting theory. The results show that the vertical stress ( ) in wells that experienced less erosion can be determined using the following equation: , where  is in psi, and z is in ft. However, wells that experienced severe erosion have vertical stress gradients higher than one psi/ft ( . The minimum horizontal stress ( ) in the hydrostatic zone can be estimated as, while in the overpressured zone, . The maximum horizontal stress ( ) in the shallow and deep hydrostatic zones can be estimated using equations: and , respectively. While in the overpressured zone, . The orientation of  is ~NE-SW, with a strike-slip faulting stress regime.

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