scholarly journals Effect of Strain-Dependent Hydraulic Conductivity of Coal Rock on Groundwater Inrush in Mining

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Haifeng Lu ◽  
Nan Shan ◽  
You-Kuan Zhang ◽  
Xiuyu Liang
Keyword(s):  
Hydraulic Conductivity ◽  
Coal Mining ◽  
Water Inflow ◽  
Rock Deformation ◽  
Triaxial Tests ◽  
Groundwater Inrush ◽  
Modified Model ◽  
Deformation And Failure ◽  
Elastic Compression ◽  
Strain Dependent

Hydraulic conductivity is an important parameter for predicting groundwater inrush in coal mining worksites. Hydraulic conductivity varies with deformation and failure of rocks induced by mining. Understanding the evolution pattern of hydraulic conductivity during mining is important for accurately predicting groundwater inrush. In this study, variations of hydraulic conductivity of rock samples during rock deformation and failure were measured using the triaxial servo rock mechanic test in a laboratory. The exponential formula of hydraulic conductivity-volume strain was proposed based on the experimental data. The finite-difference numerical model FLAC3D was modified by replacing constant hydraulic conductivity with the strain-dependent hydraulic conductivity. The coupled water flow and rock deformation and failure were simulated using the modified model. The results indicate that in the early time, the rocks undergo elastic compression with increasing rock strain, resulting in a decrease in hydraulic conductivity; then, the microcracks and fissures appear in the rock after it yields results in a sudden jump in hydraulic conductivity; in the later time, the hydraulic conductivity decreases gradually again owing to the microcracks and fissures that were compacted. The conductivity exponentially decreases with the volumetric strain during the periods of both elastic compression and postyielding. The simulated stress-strain curves using the modified model agree with the triaxial tests. The modified model was applied to the groundwater inrush of a coal mining worksite in China. The simulated water inflow agrees well with the observed data. The original model significantly underestimates the water inflow owing to it to neglect the variations of the hydraulic conductivity induced by mining.

Water Probe in Coal Mine Working Face

2013 ◽  
Vol 734-737 ◽  
pp. 888-891
Author(s):  
Chen Shi
Keyword(s):  
Hydraulic Conductivity ◽  
Coal Mining ◽  
Coal Mine ◽  
Mine Working ◽  
Mine Water ◽  
Theoretical Calculations ◽  
Drainage System ◽  
Water Inflow ◽  
Interference Method ◽  
Working Face

Water probe in coal mine working face is an important part of the work of Mine Water. When the mine working face close to the aquifer hydraulic conductivity faults, underground rivers, caves and hydraulic conductivity collapse columns; extractive damaging effects, water probe should be done. However, the calculation of water inflow face probe has no feasible way. This paper discussed the theoretical calculations to explore water drilling inflow well group interference method and provides the basis for provision of drainage system for the coal mining enterprises.

scholarly journals Analysis of Seepage Characteristics of a Foundation Pit with Horizontal Waterproof Curtain in Highly Permeable Strata

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1303
Author(s):  
Chenghua Shi ◽  
Xiaohe Sun ◽  
Shengli Liu ◽  
Chengyong Cao ◽  
Linghui Liu ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Theoretical Calculation ◽  
Calculation Method ◽  
Design Method ◽  
Water Pressure ◽  
Water Inflow ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Seepage Characteristics

At present, jet-grouted horizontal waterproof curtain reinforcement has become an essential method for deep foundation pit groundwater control. However, there is still a lack of an effective theoretical calculation method for horizontal waterproof curtain reinforcement, and there is little research on the seepage laws of foundation pits under different horizontal waterproof curtain conditions. Based on Darcy’s seepage theory, theoretical analysis models of deep foundation pit seepage were established considering the effect of a horizontal curtain in a highly permeable formation. Through the established models, the calculation method of the water inflow and the water pressure under the condition of a horizontal curtain was derived. Then through indoor tests, the reliability of the theoretical calculation method was verified. Furthermore, the established theoretical calculation method is used to analyze the influence of various factors on the water inflow and the water pressure, such as the ratio of hydraulic conductivity of the horizontal curtain to surrounding soil, thickness, and reinforcement position of the horizontal curtain. It is found that the hydraulic conductivity ratio has the most significant influence on the seepage characteristics of the foundation pit. Finally, the design method was applied to an example of the horizontal waterproof curtain of the foundation pit, which is located at Juyuanzhou Station in Fuzhou (China). The water inflow per unit area is 0.36 m3/d in the foundation pit, and this implies that the design method of the horizontal waterproof curtain applied for the excavation case is good and meets the requirements of design and safety.

Research on Hydraulic Conductivity of Coarse Sandstone under Triaxial Compression

2011 ◽  
Vol 94-96 ◽  
pp. 1146-1151 ◽  
Author(s):  
Guan Rong ◽  
Xiao Jiang Wang
Keyword(s):  
Hydraulic Conductivity ◽  
Circumferential Strain ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Test Results ◽  
Stress Strain ◽  
Deformation And Failure ◽  
Maximum Value ◽  
Strain Process ◽  
Peak Value

Permeability test for complete stress-strain process of coarse sandstone were carried out in triaxial test instrument. On the basis of test results, the influence of confining pressure and strain on the hydraulic conductivity was discussed. It is shown that in the complete stress-strain process, hydraulic conductivity changes in the law that presents the same character with the curve of stress-strain. The hydraulic conductivity reduces slightly with the increase of deviatoric stress in the stage of micro fracture compressing and elastic; In the elastoplastic stage, along with the expansion of new fractures, the hydraulic conductivity increases slowly at first and then reaches sharply to the maximum value after peak point; In the post-peak stage, the fracture which controls the hydraulic conductivity of coarse sandstone is compressed because of the confining pressure and the hydraulic conductivity decreases. During the process of deformation and failure, the hydraulic conductivity is more sensitive to the change of circumferential strain. With the increase of confining pressure, the increased value from initial to peak value and the decreased value from peak to residual value decreases.

Modified Model for Hydraulic Conductivity of Clayey Soil under Shear

2019 ◽  
Vol 19 (11) ◽  
pp. 06019015 ◽  
Author(s):  
Qianhui Liu ◽  
Yongkang Wu ◽  
Quanming Li ◽  
Yuzhen Yu ◽  
He Lv
Keyword(s):  
Hydraulic Conductivity ◽  
Clayey Soil ◽  
Modified Model

scholarly journals Undrained Behavior of Microbially Induced Calcite Precipitated Sand with Polyvinyl Alcohol Fiber

2019 ◽  
Vol 9 (6) ◽  
pp. 1214 ◽  
Author(s):  
Sun-Gyu Choi ◽  
Tung Hoang ◽  
Sung-Sik Park
Keyword(s):  
Hydraulic Conductivity ◽  
Polyvinyl Alcohol ◽  
Friction Angle ◽  
Triaxial Tests ◽  
Calcite Precipitation ◽  
Environment Friendly ◽  
Ottawa Sand ◽  
Polyvinyl Alcohol Fiber ◽  
Constant Head ◽  
Undrained Behavior

Microbially induced calcite precipitation can cement sand and is an environment-friendly alternative to ordinary Portland cement. In this study, clean Ottawa sand was microbially treated to induce calcite contents (CCs) of 0%, 2%, and 4%. Polyvinyl alcohol fiber was also mixed with the sand at four different contents (0%, 0.2%, 0.4%, and 0.6%) with a constant CC of 4%. A series of undrained triaxial tests was conducted on the treated sands to evaluate the effects of the calcite treatment and fiber inclusion. Their hydraulic conductivity was also determined using a constant head test. As the CC increased from 0% to 4%, the friction angle and cohesion increased from 35.3° to 39.6° and from 0 to 93 kPa, respectively. For specimens with a CC of 4%, as the fiber content increased from 0% to 0.6%, the friction angle and cohesion increased from 39.6° to 42.8° and from 93 to 139 kPa, respectively. The hydraulic conductivity of clean Ottawa sand decreased by a factor of more than 100 as the CC increased from 0% to 4%. The fiber inclusion had less effect on the hydraulic conductivity of the specimen with 4% CC.

The Impact Analysis of Ground Stability Caused by Exploiting Underground Coal

2011 ◽  
Vol 243-249 ◽  
pp. 3147-3150
Author(s):  
Shu Xian Liu ◽  
Xiao Gang Wei ◽  
Shu Hui Liu ◽  
Li Ping Lv
Keyword(s):  
Numerical Simulation ◽  
Coal Mining ◽  
Impact Analysis ◽  
Shear Failure ◽  
Failure Process ◽  
Wall Rock ◽  
Strong Impact ◽  
Element Analysis ◽  
Deformation And Failure ◽  
The Impact

Disaster caused by exploiting underground coal is due to original mechanical equilibrium of underground rock has been destroyed when underground coal is exploited. And Stress redistribution and stress concentration of wall rock in the goaf happened too. As many complex factors exist such as complex structures of ground, multivariate stope boundary conditions, many stochastic mining factors and so on, it is difficult to evaluate the damage of the geological environment caused the excavation by surrounding underground coal accurately. Besides that, the coexistence of continuous and discontinuous of deformation and failure of wall rock make a strong impact on the ground, and the co-exist of tension, compression and shear failure also pay a great deal contribution to the destroy. Due to the mechanical property and deformation mechanism of goaf are complex , changeable, nonlinear and probabilistic, which changes with in space and time dynamically, it can not be studied analytically by the classical mathematical model and the theory of mechanics computation. Through finite element analysis software ABAQUS, a numerical simulation of the process of underground coal mining have been made. After make a research of the simulation process, it shows the change process of stress environment of wall rock and deformation and failure process of rock mass during the process of coal mining. The numerical simulation of the process can provide theoretical basis and technical support to the protection and reinforcement of laneway the process of coal excavation. Besides that, it also provides a scientific basis and has a great significance to reasonable Excavation and control of mind-out area.

scholarly journals Acoustic Emission Behavior of Rock-Like Material Containing Two Flaws in the Process of Deformation Failure

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Quan-Sheng Liu ◽  
Jie Xu ◽  
Bin Liu ◽  
Jing-Dong Jiang
Keyword(s):  
Crack Initiation ◽  
Crack Coalescence ◽  
Rock Deformation ◽  
Crack Initiation And Propagation ◽  
Deformation And Failure ◽  
Initiation And Propagation ◽  
Final Failure ◽  
Emission Behavior ◽  
Ae Location ◽  
Acoustic Emission Behavior

Many sudden disasters (such as rock burst) by mining extraction originate in crack initiation and propagation. Meanwhile a large number of shock waves are produced by rock deformation and failure. With the purpose of investigating crack coalescence and failure mechanism in rock, experimental research of rock-like materials with two preexisting flaws was performed. Moreover, the AE technique and photographic monitoring were adopted to clarify further the procedure of the crack coalescence and failure. It reveals that AE location technique can record the moments of crack occurrences and follow the crack growth until final failure. Finally, the influence of different flaw geometries on crack initiation strength is analyzed in detail. This research provides increased understanding of the fracture mechanism of mining-induced disasters.

scholarly journals Folded fabric tunes rock deformation and failure mode in the upper crust

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
F. Agliardi ◽  
M. R. Dobbs ◽  
S. Zanchetta ◽  
S. Vinciguerra
Keyword(s):  
Failure Mode ◽  
Rock Deformation ◽  
Upper Crust ◽  
Deformation And Failure
Sign in / Sign up

Export Citation Format

Share Document