Numerical Analysis of Grouting and Blocking of Deep Large Section Shaft at Working Face

2012 ◽  
Vol 157-158 ◽  
pp. 865-869
Author(s):  
Ji Ming Zhu ◽  
Wen Quan Zhang ◽  
Hai Ling Yu ◽  
Xiang Lan Liu
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Water Channel ◽  
Seepage Flow ◽  
Water Inflow ◽  
Seepage Water ◽  
Large Section ◽  
Working Face ◽  
Water Block

To estimate the effect of deep large section Shaft Face Grouting for water block, the mathematical model is obtained according to the seepage theory. The numerical model for calculation is established by the program ABAQUS. The laws of change of pore water pressure, the effect area of dewatering, the velocity of seepage, water inflow of shaft working face before and after grouting is obtained by numerical simulation. It is shown that the grouting can effectively plug water channel of cracked surrounding rock, and prevent the pore water pressure lowering range to be larger. The working face seepage flow velocity was significantly reduced. The water inflow is decreased significantly. The safety of the shaft construction and the stability structure of shaft lining and upper strata are ensured by grouting. The numbers of grout stop and grouting construction can be largely reduced. The economic benefit is obvious. The scientific reference is provided for deep large section Shaft Face Grouting for water block.

scholarly journals A Simulation Study on the Spatial-Temporal Characteristics of Pore Water Pressure and Roof Water Inrush in an Aquiclude

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Tao Yang ◽  
Ji Li ◽  
Longwen Wan ◽  
Sheng Wang
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Water Inrush ◽  
Pressure Change ◽  
Coupling Model ◽  
Early Warning Systems ◽  
Temporal Characteristics ◽  
Working Face

As the working face advances, the overlying aquiclude is subjected to periodic dynamic loads, causing pore water pressure distortion, which provides important forewarning for a water inrush disaster in shallow coal seams. In order to analyze the pore water pressure in an aquiclude and determine the spatial-temporal characteristics of the water inrush, the aquiclude is simplified into a saturated, porous, liquid-solid medium and a viscoelastic dynamic model is created to obtain the analytical solution of the pressure distribution. FLAC3D is used to develop a fluid-solid coupling model and to analyze the characteristics of the pressure change and overburden under different mining intensities. This study on pore water pressure in an aquiclude and the determination of the spatial-temporal characteristics of the water inrush provides a foundation for developing early-warning systems for roof water inrush.

scholarly journals Mechanical Properties of Sandstone Roof and Surrounding-Rock Control of Mining Roadways Subject to Reservoir Water Disturbance

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Bin Ma ◽  
Zaiqiang Hu ◽  
Xingzhou Chen ◽  
Lili Chen ◽  
Wei Du
Keyword(s):  
Crack Initiation ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Surrounding Rock ◽  
Water Inflow ◽  
Reservoir Water ◽  
Deformation And Failure ◽  
Joint Dislocations ◽  
Rock Structure

Sandstone-roofed roadways are susceptible to deformation and failure caused by reservoir-water-induced disturbances, thereby compromising human safety. Using rock-mechanics testing techniques, numerical simulations, and engineering principles, this study investigates the strength, deformation, and pore-structure characteristics of sandstone roofs as well as means to support the surrounding rock structure. The results obtained in this study reveal that the residual strain is proportional to the pore-water pressure, which, in turn, causes a significant reduction in the elastic modulus during the unloading phase. Furthermore, an increase in the pore-water pressure causes the shear failure of specimens in compression. The delay between crack initiation and specimen-volume expansion decreases. Moreover, the specimen demonstrates increased deformation and failure responses to changes in the confining pressure, thereby resulting in accelerated conversion. Changes in water inflow can be correlated to crack initiation, propagation, and fracture. This water inflow gradually increases with an increase in the osmotic pressure. Correspondingly, the volumetric strain required for maximum water inflow undergoes a gradual decrease. The increased water inflow can be considered a precursor to specimen failure. In addition, fractures in the surrounding rock structures are mainly caused by joint dislocations. The increase in pore pressure promotes the development of dislocation fractures in the deep surrounding rocks. Subsequently, these fractures overlap with their open counterparts to form large fractures; this increases the roadway-roof subsidence and layer separation of the shallow surrounding rocks, thereby further increasing the fracture count. Lastly, the use of high-performance rock bolts, cable-bolt reinforcements, and W-shaped steel bands is expected to ensure the stability of rocks surrounding sandstone-roofed roadways subject to water-pressure disturbances.

Hydrological response of hillslope soils above a debris-slide headscarp

1999 ◽  
Vol 36 (6) ◽  
pp. 1111-1122 ◽  
Author(s):  
R J Fannin ◽  
J Jaakkola
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Ground Surface ◽  
Seepage Flow ◽  
Hydrological Response ◽  
Linear Distribution ◽  
Soil Matrix ◽  
Maximum Rainfall ◽  
Debris Slide

The Jamieson Creek debris slide initiated in thin soils over a competent bedrock surface, on a planar section of hillslope, during a heavy rainstorm in November 1990. An array of automated piezometers and tensiometers was placed along a 22 m wide section of the headscarp in 1997 to monitor the temporal variation of pore-water pressures. Interpretation of the data addresses the hydrologic response to the storms in October and November 1997. The piezometers, which were designed for installation by driving, reveal very localized responses in what otherwise appears to be a uniform soil matrix. Peak positive pressures occur at the time of maximum rainfall intensity. The tensiometers indicate the hydrological response at the ground surface appears uncoupled from that at the bedrock interface. Implications of the extreme spatial variability in pore-water pressure are evaluated for conceptual models of hillslope hydrology. The assumption of parallel seepage flow is widely adopted in translational slope stability analyses, imposing a linear distribution of pore-water pressure with depth. None of the reported field data are consistent with such a linear distribution with depth or a uniform response across the slope.

scholarly journals SEEPAGE FLOW IN A BREAKER ZONE

2011 ◽  
Vol 1 (32) ◽  
pp. 54
Author(s):  
Taro Kakinuma ◽  
Shizuka Ohishi ◽  
Kazuo Nakamura
Keyword(s):  
Pore Water ◽  
Incident Wave ◽  
Time Variation ◽  
Wave Breaking ◽  
Laboratory Experiments ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Maximum Velocity ◽  
Seepage Flow ◽  
Wave Period

Seepage velocities in several breaker zones were measured with dye for visualization. Pressure gauges were also installed to obtain pore water pressure. Three cases of different incident-wave periods were treated in laboratory experiments. The time-averaged pore water pressure was higher near the shoreline, resulting in the seepage flow, the maximum velocity of which was larger as the incident-wave period was longer, generally moving from onshore to offshore. The penetrated water flowed out from the permeable seabed at a bar top or on the rather offshore side of the bar top if a bar was developed remarkably. The pore water pressure in the breaker zone showed time variation depending on the wave phases including wave breaking and bore propagation. There was a phase when the pore water pressure was locally low below the bar.

scholarly journals Seismic Performance Evaluation of Agricultural Reservoir Embankment through Shaking Table Tests

2021 ◽  
Vol 21 (3) ◽  
pp. 151-161
Author(s):  
Younghak Lee ◽  
Junghyun Ryu ◽  
Bora Yoon ◽  
Joon Heo ◽  
Dalwon Lee
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Pressure Ratio ◽  
Horizontal Displacement ◽  
National Standards ◽  
Shaking Table ◽  
Seepage Water ◽  
Shaking Table Tests ◽  
Experimental Conditions

In this study, shaking table tests were performed to compare and analyze the acceleration response, displacement behavior, and pore-water pressure behavior of reservoirs with parapets installed to prevent overtopping of deteriorative homogeneous reservoirs. During the shaking table tests, the experimental conditions were divided into four cases considering the range and magnitude of seismic acceleration according to national standards. The vibration-type waveform (Gongen) and shock-type waveform (Minogawa) were applied as input waveforms. The acceleration amplification ratios of both vibration- and shock-wave types were the largest in the dam crest, and the amplification ratio decreased as the design earthquake acceleration increased. In addition, the horizontal displacement was maximum on the upstream slope, owing to the influence of seepage water, and the vertical displacement was maximum on the dam crest, owing to the self-weight effect of the parapet structure. A comparison of the waveform results indicates that the vibration-type waveform may exhibit a more significant effect on the embankment zone displacement than the shock-type waveform. However, when the safety standards for the horizontal displacement, settlement ratio, and excess pore-water pressure ratio were applied, the embankment was stable within the allowable range in both the shock-type and vibration-type waveforms. Therefore, the parapet structure is expected to influence the overflow resistance and stability of embankments positively.

TIME TO THE END OF PRIMARY CONSOLIDATION (EOP) OF SOFT CLAYEY SOILS: CONCERNING THE EFFECT OF ATTERBERG’S LIMIT AND CYCLIC LOADING HISTORY

2019 ◽  
Vol 128 (2B) ◽  
pp. 29-41
Author(s):  
Trần Thanh Nhàn
Keyword(s):  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Clayey Soils ◽  
Loading History ◽  
Cyclic Shear ◽  
Wide Range ◽  
Primary Consolidation ◽  
Time Required

In order to observe the end of primary consolidation (EOP) of cohesive soils with and without subjecting to cyclic loading, reconstituted specimens of clayey soils at various Atterberg’s limits were used for oedometer test at different loading increments and undrained cyclic shear test followed by drainage with various cyclic shear directions and a wide range of shear strain amplitudes. The pore water pressure and settlement of the soils were measured with time and the time to EOP was then determined by different methods. It is shown from observed results that the time to EOP determined by 3-t method agrees well with the time required for full dissipation of the pore water pressure and being considerably larger than those determined by Log Time method. These observations were then further evaluated in connection with effects of the Atterberg’s limit and the cyclic loading history.

Conjectures, Hypotheses, and Theories of Drumlin Formation (In memory of Stanislaw Baranowski)

1981 ◽  
Vol 27 (97) ◽  
pp. 503-505 ◽  
Author(s):  
Ian J. Smalley
Keyword(s):  
Shear Strength ◽  
Pore Water ◽  
Stress Level ◽  
Critical Stress ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Glacial Till ◽  
Forming Process ◽  
Stress Levels

AbstractRecent investigations have shown that various factors may affect the shear strength of glacial till and that these factors may be involved in the drumlin-forming process. The presence of frozen till in the deforming zone, variation in pore-water pressure in the till, and the occurrence of random patches of dense stony-till texture have been considered. The occurrence of dense stony till may relate to the dilatancy hypothesis and can be considered a likely drumlin-forming factor within the region of critical stress levels. The up-glacier stress level now appears to be the more important, and to provide a sharper division between drumlin-forming and non-drumlin-forming conditions.

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