Analysis of Separation and Dislocation Characteristics of Layered Roof in the Mined-Out Areas

2012 ◽  
Vol 256-259 ◽  
pp. 75-80
Author(s):  
Shu Ren Wang ◽  
Zhong Qiu Wang
Keyword(s):  
Coal Seam ◽  
Lateral Pressure ◽  
Slow Growth ◽  
Gradual Increase ◽  
Shape Variation ◽  
Maximum Value ◽  
Mining Width ◽  
Dip Angle ◽  
Maximum Separation ◽  
Flat Arch

The computational model based on the shallow mined-out areas was built by using FLAC3D, and the separation and dislocation characteristics of the layered roof in the mined-out areas were analyzed under different conditions. The results showed that the maximum value of the layered roof separation increased with the increase of the mining width, and that value decreased with the increase of lateral pressure and the cohesion between layers. The separation curves of the layered roof showed the shape variation from the symmetry flat arch to the asymmetric steeple arch and then to the linear form, the maximum separation value of the layered roof exhibited a three-stage tendency of a gradual increase, a steep reduction and a slight change, and the maximum dislocation value of the layered roof presented a two-stage tendency of firstly slow growth and then rapid growth with the increase of the dip angle of coal seam.

Adsorption Research of Polymer on Oil Sands in Qidongyi Block of Xinjiang Conglomerate Reservoir

2014 ◽  
Vol 580-583 ◽  
pp. 2518-2523
Author(s):  
Xiao Bin Nie ◽  
Ying Guo ◽  
Qing Xiang Lou ◽  
Wei Dong Liu ◽  
Ling Hui Sun ◽  
...  
Keyword(s):  
Oil Sands ◽  
Adsorption Process ◽  
Slow Growth ◽  
Stable State ◽  
Polymer Flooding ◽  
Equilibrium Adsorption ◽  
Negative Effects ◽  
Polymer Molecules ◽  
Maximum Value ◽  
Adsorption Quantity

In the process of polymer flooding in porous media, polymer was detained due to interactions between surface adsorption and polymer molecules, and this could lead to negative effects on oil displacement. For polymer adsorption in Xinjiang conglomerate reservoir, HPLC analysis was adopted to study the static and dynamic laws. Results have showed that the adsorption process could be divided into 3 stages: rapid growth, slow growth and stable state. With the loss of polymer molecular weight, equilibrium adsorption quantity reduces gradually. The adsorption amount is different for the same polymer on four types of oil sands. For equilibrium adsorption, the maximum value is argillaceous sandstone, followed by conglomeratic sandstone.The third is argillaceous gravel, and the minimum is sand gravel. For polymer flooding in conglomerate cores, the dynamic retention amount of seriate conglomerate is much greater than that of fine particle conglomerate. These data have provided reference for project design of polymer flooding in conglomerate reservoir.

scholarly journals Key Parameters of Roof Cutting of Gob-Side Entry Retaining in a Deep Inclined Thick Coal Seam with Hard Roof

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 934 ◽  
Author(s):  
Jinzhu Hu ◽  
Manchao He ◽  
Jiong Wang ◽  
Zimin Ma ◽  
Yajun Wang ◽  
...  
Keyword(s):  
Numerical Model ◽  
Coal Seam ◽  
Economic Benefits ◽  
Surrounding Rock ◽  
Thick Coal Seam ◽  
Hard Roof ◽  
Coal Recovery ◽  
Rock Structure ◽  
Different Depths ◽  
Dip Angle

Gob-side entry retaining by roof cutting (GERRC) employed in a deep inclined thick coal seam (DITCS) can not only increase economic benefits and coal recovery, but also optimize surrounding rock structure. In accordance with the principles of GERRC, the technology of GERRC in DITCS is introduced and a roof-cutting mechanical model of GERRC is proposed to determine the key parameters of the depth and angle of RC. The results show that the greater the RC angle, the easier the caving of the goaf roof, but the length of cantilever beam increases. The depth of RC should account for the dip angle of the coal seam when the angle is above 20°. Increasing the coal seam dip angle could reduce the volume of rock falling of the goaf roof, but increase the filling height of the upper gangue to slide down. According to numerical model analysis of the stress and displacement of surrounding rock at different depths and angles of RC, when the depth of RC increased from 9 m to 13 m, the distance between the stress concentration zone and the coal side is increased. When the angle of RC increased from 0° to 20°, the value of roof separation is decreased. GERRC was applied in a DITCS with 11 m depth and 20° RC angle, and the field-measured data verified the conclusions of the numerical model.

What drives the vital rates of secondary hemiepiphytes? A first assessment for three species of Heteropsis (Araceae) in the Colombian Amazon

2015 ◽  
Vol 31 (3) ◽  
pp. 251-265 ◽  
Author(s):  
María Paula Balcázar-Vargas ◽  
Tinde R. van Andel ◽  
Paul Westers ◽  
Pieter A. Zuidema
Keyword(s):  
Growth Rates ◽  
Vegetative Propagation ◽  
Slow Growth ◽  
Gradual Increase ◽  
Leaf Size ◽  
Stem Length ◽  
Vital Rates ◽  
Size Number ◽  
Colombian Amazon ◽  
Study Species

Abstract:Secondary hemiepiphytes rely on other plants (hosts) to grow vertically. After germinating on the forest floor, their seedlings search a host to ascend. We recorded information on survival, growth, reproduction and vegetative propagation of three Heteropsis species, to evaluate what drives their vital rates. We measured 700 individuals of each study species between 2007 and 2009 in the southern Colombian Amazon. A gradual increase in stem length, leaf size, number of roots and plagiotropic branches was found with increasing height of Heteropsis individuals on their hosts. Survival of leafless non-climbing seedlings was very low (28% annually); increasing substantially (84–94%) once the seedling had ascended a host. The three Heteropsis species presented slow height growth rates (c. 2–8 cm y−1) with large variation, while a substantial percentage of the stems (31–62%) did not grow or dried out. Vegetative propagation in Heteropsis may act as a dispersion-propagation strategy to find a suitable host and reach the canopy again after falling. The slow growth rates suggest that Heteropsis individuals that have reached the canopy are rather old. Once plants have reached the tree crowns, their longevity is largely determined by the survival of the host tree.

scholarly journals Investigation of Hydraulic Fracturing Crack Propagation Behavior in Multi-Layered Coal Seams

2020 ◽  
Vol 10 (3) ◽  
pp. 1153 ◽  
Author(s):  
Shirong Cao ◽  
Xiyuan Li ◽  
Zhe Zhou ◽  
Yingwei Wang ◽  
Hong Ding
Keyword(s):  
Coal Seam ◽  
Hydraulic Fracturing ◽  
Crack Propagation ◽  
Principal Stress ◽  
Fracture Propagation ◽  
Clean Energy ◽  
Burial Depth ◽  
Coal Seams ◽  
Initiation Pressure ◽  
Dip Angle

Coalbed methane is not only a clean energy source, but also a major problem affecting the efficient production of coal mines. Hydraulic fracturing is an effective technology for enhancing the coal seam permeability to achieve the efficient extraction of methane. This study investigated the effect of a coal seam reservoir’s geological factors on the initiation pressure and fracture propagation. Through theoretical analysis, a multi-layered coal seam initiation pressure calculation model was established based on the broken failure criterion of maximum tensile stress theory. Laboratory experiments were carried out to investigate the effects of the coal seam stress and coal seam dip angle on the crack initiation pressure and fracture propagation. The results reveal that the multi-layered coal seam hydraulic fracturing initiation pressure did not change with the coal seam inclination when the burial depth was the same. When the dip angle was the same, the initiation pressure linearly increased with the reservoir depth. A three-dimensional model was established to simulate the actual hydraulic fracturing crack propagation in multi-layered coal seams. The results reveal that the hydraulic crack propagated along the direction of the maximum principal stress and opened in the direction of the minimum principal stress. As the burial depth of the reservoir increased, the width of the hydraulic crack also increased. This study can provide the theoretical foundation for the effective implementation of hydraulic fracturing in multi-layered coal seams.

Numerical Simulation of Compressive Experiment of Coal Seam in Deep Underground for Geological Storage of Carbon Dioxide

2013 ◽  
Vol 387 ◽  
pp. 189-192
Author(s):  
Feng Shan Han ◽  
Xin Li Wu
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Shear Failure ◽  
Lateral Pressure ◽  
Failure Process ◽  
Absorption Capacity ◽  
Geological Storage ◽  
Modeling Tools ◽  
Storage Reservoirs ◽  
Deep Underground

The geological storage of has been recognized as an important strategy to reduce emission in the atmosphere. Coal seam has strong absorption capacity for , hence the coal seam can be used as geological storage reservoirs, simple and easy to use modeling tools would be valuable in assessing the performance of deep underground geological storage. In this paper failure process of coal seam in deep underground under triaxial compressive experiment is presented by numerical simulation. That is of significance and valuable to those subjects of investigation of strength of coal seam in deep underground and mechanism of propagation and coalescence and evolvement of crack for coal seam in deep underground, it is shown by numerical simulation that failure shape of coal seam in deep underground under triaxial compressive experiment of lateral pressure of 25Mpa is typically shear failure, and characteristic of deformation is obviously elastic-brittle, which is significance to understand the performance of the coal seam in deep underground

Adsorption Research of a Polymer on Oil Sands in Xinjiang Conglomerate Reservoir

2014 ◽  
Vol 953-954 ◽  
pp. 1171-1175
Author(s):  
Ying Guo ◽  
Wei Dong Liu ◽  
Jian Long Xiu ◽  
Ling Hui Sun
Keyword(s):  
Oil Sands ◽  
Adsorption Process ◽  
Slow Growth ◽  
Stable State ◽  
Negative Effects ◽  
Isothermal Method ◽  
Polymer Molecules ◽  
The Third ◽  
Maximum Value ◽  
Equation Analysis

In the process of polymer flooding in porous media, polymer was detained because of interactions between surface adsorption and polymer molecules, and this could lead to negative effects on oil displacement. For polymer static adsorption in Xinjiang conglomerate reservoir, both of the HPLC analysis and Langmuir isothermal method were adopted to study on the rules. Results have showed that the adsorption process could be divided into 3 stages: rapid growth, slow growth and stable state. The adsorption of polymer KA on oil sands is in line with the Langmuir isotherm law. The adsorption amount is different for polymer KA on four types of oil sands. For equilibrium adsorption, the maximum value is from argillaceous sandstone, followed by conglomeratic sandstone. The third is argillaceous gravel, and the minimum is sand gravel. Adsorption equation analysis is consistent with the experimental principle statement.

The effect of cholesterol on measured interaction and compressibility of dipalmitoylphosphatidylcholine bilayers

1980 ◽  
Vol 58 (10) ◽  
pp. 959-968 ◽  
Author(s):  
R. P. Rand ◽  
V. A. Parsegian ◽  
J. A. C. Henry ◽  
L. J. Lis ◽  
M. McAlister
Keyword(s):  
Phase Separation ◽  
Lateral Pressure ◽  
Cholesterol Content ◽  
Repulsive Force ◽  
Density Fluctuations ◽  
Excess Water ◽  
Lamellar Phases ◽  
Van Der Waals Attraction ◽  
Low Cholesterol ◽  
Maximum Separation

We have examined the phase diagram of dipalmitoylphosphatidylcholine (DPPC) – cholesterol – water mixtures at low cholesterol content, and report phase separation between 3 and 10 mol% cholesterol. The two lamellar phases at equilibrium in this region appear to be pure DPPC and 11 mol% cholesterol in DPPC. For these two lamellar phases, which are made up of alternating layers of water and bimolecular lipid leaflets, we have measured the forces of interaction between leaflets and the lateral pressure and compressibility of the leaflets. Both bilayers experience a strong repulsive force when forced together only a few ångströms (1 Å = 0.1 nm) closer than their maximum separation in excess water. However, the presence of 11 mol% cholesterol causes the bilayers to move apart to 35-Å separation from the 19-Å characteristic of pure DPPC in excess water. This swelling may result from a decrease in van der Waals attraction between bilayers or from an increase in bilayer repulsion. Differences in bilayer interaction can be a cause for phase separation. More importantly these differences can cause changes in the composition of regions of membranes approaching contact. At 11 mol%, cholesterol substantially increases the lateral compressibility of DPPC bilayers leading to higher lateral density fluctuations and potentially higher bilayer permeability.

Numerical investigation of the effects of coal seam dip angle on coal wall stability

2017 ◽  
Vol 100 ◽  
pp. 298-309 ◽  
Author(s):  
Qiangling Yao ◽  
Xuehua Li ◽  
Boyang Sun ◽  
Minghe Ju ◽  
Tian Chen ◽  
...  
Keyword(s):  
Coal Seam ◽  
Numerical Investigation ◽  
Coal Wall ◽  
Dip Angle

Numerical Analysis of a Pile-Anchor Retaining Structure of Deep Foundation Pit Engineering

2014 ◽  
Vol 638-640 ◽  
pp. 496-502
Author(s):  
Ying Wang ◽  
Jiang Bo Shi
Keyword(s):  
Earth Pressure ◽  
Horizontal Displacement ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Deformation Control ◽  
Maximum Value ◽  
Negative Moment ◽  
Dip Angle ◽  
Pile Length

Based on a deep foundation pit engineering of Tangshan, considering the interaction of pile-anchor-soil, the finite difference software FLAC3D is adopted in this paper to simulate and analyze the effect of dip angle of anchor and the embedded depth of pile on the horizontal displacement and the variation laws of earth pressure, horizontal displacement of pile with the process of excavation. The results show that the maximum value of horizontal displacement and positive moment of pile appear in 0.85H (H stands for the depth of excavation) and the negative moment appears in 1.3H after the excavation; the maximum value of active and passive earth pressure appear in 1.3H rather than the bottom in the range of pile length; the requirements of deformation control and overall stability of foundation pit can be satisfied with 0.5H which as the embedded depth of the pile, and the dip angle of anchor is appropriate when it ranges from 5°to 25°but less than 30°.

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