Experimental Investigation of Simulating Similar Materials of Multi-Seam Mining in Steep

2011 ◽  
Vol 255-260 ◽  
pp. 3765-3769
Author(s):  
Kui Xing Liu ◽  
Xiao Gang Wei ◽  
Shu Xian Liu ◽  
Li Ping Lv
Keyword(s):  
Similarity Index ◽  
Physical And Mechanical Properties ◽  
Material Model ◽  
Prototype Model ◽  
Similar Material ◽  
Initial State ◽  
Deformation And Failure ◽  
Model Method ◽  
Movement And Deformation ◽  
Seam Mining

The similar material model method is used to simulate to the movement of cover rock and ground which is caused by mining underground coal, the substance of deformation and failure law of similar material model method is that artificial materials which are used in the experiment have similar physical and mechanical properties as archetype, affinity constants of geometry, movement and force are used as similarity index and criteria in the simulation experiment as the most important factors. The prototype model is made into a certain proportion model in reduction, and the initial state and boundary conditions of model must be similar as archetype. Then exploit the simulating model, the regular patterns of fault destruction, curve, movement and deformation of cover rock can be discovered in the process of exploiting the simulating model, and the movement and deformation of the surface and its sphere of influence can also be got. Finally the observations of model can be calculated and projections up to the prototype by the similarity index, so the most important regular pattern of the prototype can be got.

Study on Failure of Soft Overburden of Fully Mechanized Top Coal Caving

2012 ◽  
Vol 446-449 ◽  
pp. 2192-2195
Author(s):  
Jin Shan Wang ◽  
Zhong Chang Wang
Keyword(s):  
Abutment Pressure ◽  
Main Roof ◽  
Material Model ◽  
Stress And Strain ◽  
Similar Material ◽  
Coal Face ◽  
Coal Wall ◽  
Internal Stress Field ◽  
Seam Mining ◽  
Step Distance

The similar material model experiment takes the NO.S2S9 coal face in DaPing coal mine as a prototype to research the characteristics of movement and failure of the soft overburden under fully mechanized top coal caving conditions. The abutment pressure distribution and periodic weighting, caving span are given by monitoring the stress and strain in the similar material model. The results show that rocks fracture extended from button with the advance of workface. The first caving step distance of main roof is 34m. The periodic caving step distance of main roof is 10m. The internal stress field is 10m and the peak abutment pressure point is 80m far away from the coal wall, while the disturbance range in anterior coal wall is 200m. Some cracks are closed in the later stage. The advance of around 300m is the distance that the water flowing fractured zone’s height reaches the highest value. The biggest height of water- flowing fractured zone is 140m. The soft overburden has strong plastic deformation capability. The synchronism of failure and movement of overburden is strong. The failured overburden is compacted and the cracks keep close with the advance of workface. The simulation experiment provides a reference bases for the application and promotion of thick seam mining technology.

Basic set of experiments for determination of mechanical properties of sand

2014 ◽  
Vol 62 (1) ◽  
pp. 129-137
Author(s):  
A. Sawicki ◽  
J. Mierczyński
Keyword(s):  
Mechanical Properties ◽  
Soil Mechanics ◽  
Physical And Mechanical Properties ◽  
Local Strain ◽  
Initial State ◽  
Laboratory Equipment ◽  
Additional Information ◽  
Basic Set ◽  
Initial Anisotropy

Abstract A basic set of experiments for the determination of mechanical properties of sands is described. This includes the determination of basic physical and mechanical properties, as conventionally applied in soil mechanics, as well as some additional experiments, which provide further information on mechanical properties of granular soils. These additional experiments allow for determination of steady state and instability lines, stress-strain relations for isotropic loading and pure shearing, and simple cyclic shearing tests. Unconventional oedometric experiments are also presented. Necessary laboratory equipment is described, which includes a triaxial apparatus equipped with local strain gauges, an oedometer capable of measuring lateral stresses and a simple cyclic shearing apparatus. The above experiments provide additional information on soil’s properties, which is useful in studying the following phenomena: pre-failure deformations of sand including cyclic loading compaction, pore-pressure generation and liquefaction, both static and caused by cyclic loadings, the effect of sand initial anisotropy and various instabilities. An important feature of the experiments described is that they make it possible to determine the initial state of sand, defined as either contractive or dilative. Experimental results for the “Gdynia” model sand are shown.

Research on Simulation Test of Coal Similar Material

2013 ◽  
Vol 850-851 ◽  
pp. 847-850 ◽  
Author(s):  
Lin Chao Dai
Keyword(s):  
Compressive Strength ◽  
Raw Materials ◽  
Similarity Theory ◽  
Design Method ◽  
Uniform Design ◽  
Physical And Mechanical Properties ◽  
Raw Material ◽  
Similar Material ◽  
Cement Ratio ◽  
Water Cement Ratio

In order to study the coal and gas outburst similar simulation experiment, coal similar material was made up based on the similarity theory. Based on the previous similar material study, the cement, sand, water, activated carbon and coal powder was selected as the raw material of similar material. Meanwhile similar material matching program with 5 factors and 6 levels was designed by using Uniform Design Method. And the physical and mechanical properties of the similar material compressive strength was measured under different proportions circumstances. The relationship between similar material and the raw materials was analyzed. The results show that choosing different materials can compound different similar materials with different requirements. And the water-cement ratio plays a decisive influence on the compressive strength of similar material. The compressive strength of similar material decreases linearly when the water-cement ratio increases.

scholarly journals INVESTIGATION OF THE GEOMECHANICAL STATE OF SOFT ADJOINING ROCKS UNDER PROTECTIVE CONSTRUCTIONS

2021 ◽  
Vol 36 (4) ◽  
pp. 61-71
Author(s):  
Serhii Nehrii ◽  
Tetiana Nehrii ◽  
Oksana Zolotarova ◽  
Serhii Volkov
Keyword(s):  
Physical And Mechanical Properties ◽  
New Approach ◽  
Soft Rocks ◽  
The Face ◽  
Geomechanical State ◽  
Rock Mass Failure ◽  
The Stability ◽  
Seam Mining ◽  
Mine Roadways

The conditions of coal seam mining in the mines of Ukraine have been considered. The problem of conducting coal mining by longwalls in the conditions of soft adjoining rocks, which concerns the protection of mine roadways located near the face, has been revealed. In such conditions, the existing protective constructions are ineffective due to the fact that they yield and get pressed into the soft rocks of the footwall. This indicated the need for research into the geomechanical state of soft rocks of the footwall. According to the results of known studies on the mechanism of rock mass failure around roadways and the data of physical and mechanical properties of the coal mass, which is represented by soft rocks, the correlation dependence has been obtained, the use of which allowed for the determination of the parameters of the rock deformation diagram and the establishment of the stability criterion of footwall rocks under the protection means and stability conditions of the geotechnical system “protective construction – adjoining rocks.” They are the basis of a new approach to ensure the stability of the roadways, which are supported behind the faces, by controlling the stress state in the system “protective construction – adjoining rocks.” This may be the basis for the development of new methods of protecting roadways in conditions of soft adjoining rocks.

scholarly journals Study on the Strata Movement Rule of the Ultrathick and Weak Cementation Overburden in Deep Mining by Similar Material Simulation: A Case Study in China

2020 ◽  
Vol 2020 ◽  
pp. 1-21 ◽  
Author(s):  
Guojian Zhang ◽  
Guangli Guo ◽  
Yi’nan Lv ◽  
Yaqiang Gong
Keyword(s):  
Material Model ◽  
Failure Pattern ◽  
Central China ◽  
Western China ◽  
Scale Transformation ◽  
Similar Material ◽  
Deep Mining ◽  
Mining Areas ◽  
Sandstone Formation ◽  
Strong Control

In the deep mining areas of western China, there exist ultrathick and weak cementation strata in the overburdens above the Jurassic coal seams, and the overburden lithology is generally moderately a little weaker than the medium-hard strata. Yet, the practical measurement indicates that the surface movement rule in this area displays the specialty that is apparently inconsistent with its lithology, which increases the uncertainty of safe production in coal mines. In this study, the similar material and numerical simulations were conducted to investigate the movement rule and failure pattern of the ultrathick and weak cementation overburden. In addition, the photographing scale transformation-time baseline parallax (PST-TBP) method was used to monitor the similar material model to makeup for the lacks of Xi'an Jiaotong University Digital Close-range Industrial Photogrammetry System (XJTUDP) software. The findings of this study can be summarized as follows. (1) To some extent, the PST-TBP method can makeup for the deficiency of the XJTUDP software because the measurement accuracy of the PST-TBP method is 0.47 mm. (2) The height of the caving zone is approximately 66 m, and the height of the water suture zone is about 112 m, which is obviously larger than that of the medium-hard and soft overburden in eastern-central China. (3) The first breaking span of the immediate roof reaches 120 m, the cyclic fracturing length is about 60 m, and the separation occurred at 43 m and 66 m above the coal seam. (4) The failure pattern of the ultrathick and weak cementation overburden is “beam-arch shell,” and the failure boundary is arch. (5) The Zhidan group sandstone and Jurassic sandstone formations have strong control effects. The Zhidan group sandstone is the main control stratum and the Jurassic sandstone formation is the secondary-control stratum. The research results provide an insight into guiding the safe mining of deep coal in the ultrathick and weak cementation overburden.

Predictive model of overburden deformation: based on machine learning and distributed optical fiber sensing technology

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wenyuan Liu ◽  
Chunde Piao ◽  
Yazhou Zhou ◽  
Chaoqi Zhao
Keyword(s):  
Machine Learning ◽  
Optical Fiber ◽  
Predictive Model ◽  
Material Model ◽  
Prevention Measures ◽  
Similar Material ◽  
Content Type ◽  
Fiber Sensing ◽  
Optical Fiber Sensing ◽  
Distributed Optical Fiber

Purpose The purpose of this paper is to establish a strain prediction model of mining overburden deformation, to predict the strain in the subsequent mining stage. In this way, the mining area can be divided into zones with different degrees of risk, and the prevention measures can be taken for the areas predicted to have large deformation. Design/methodology/approach A similar-material model was built by geological and mining conditions of Zhangzhuang Coal Mine. The evolution characteristics of overburden strain were studied by using the distributed optical fiber sensing (DOFS) technology and the predictive model about overburden deformation was established by applying machine learning. The modeling method of the predictive model based on the similar-material model test was summarized. Finally, this method was applied to engineering. Findings The strain value predicted by the proposed model was compared with the actual measured value and the accuracy is as high as 97%, which proves that it is feasible to combine DOFS technology with machine learning and introduce it into overburden deformation prediction. When this method was applied to engineering, it also showed good performance. Originality/value This paper helps to promote the application of machine learning in the geosciences and mining engineering. It provides a new way to solve similar problems.

YIELD DESIGN HOMOGENIZATION METHOD FOR COMPACTION OF MONOSIZED SPHERICAL POWDERS

2010 ◽  
Vol 02 (03) ◽  
pp. 457-488 ◽  
Author(s):  
BENABBES ANOUAR ◽  
SIAD LARBI ◽  
DORMIEUX LUC ◽  
WING KAM LIU
Keyword(s):  
New York ◽  
Finite Element ◽  
Triaxial Compression ◽  
Ceramic Powder ◽  
Material Model ◽  
Homogenization Method ◽  
Spherical Particles ◽  
Initial State ◽  
Whole Process ◽  
Kinematic Approach

The compaction of a package of monosized spherical solid grains by rate-independent plasticity deformation is examined in this paper through the use of both yield design homogenization method and finite element simulation. Both modes of compaction, isostatic and closed die, are considered. In this study, the arrangement of powder consists of hexagonal array of identical spherical grains touching each other in its initial state. During the compaction process the response of the powder compacts is monitored in terms of behaviors of appropriate representative unit cells subject to axisymmetrical loading conditions. The kinematic approach of the yield design homogenization method has been used to determine external estimates of macroscopic strength criteria of powders at various stages of compaction. The obtained upper bound estimates are based on consideration of discontinuous incompressible velocity fields satisfying conditions of homogeneous strain rate. The shapes and sizes of the macroscopic yield surfaces are determined at various stages of compaction and it has been found that they depend upon the loading history as well as the relative density of the compact. Finite element simulations similar to those of Ogbonna N. and Fleck N. A. [1995] "Compaction of an array of spherical particles," Acta Metall. Mater.43(2), 603–620. have also been performed in order to (i) obtain the deformation modes as well as the evolution of the deformation mechanism of the powder compact during the whole process of compaction; (ii) derive the evolution of contact sizes between adjacent grains; (iii) examine the dependence of the macroscopic yield surface upon the degree of compaction, using the "yield probing technique" Gurson, A. L. and Yuan, D. W. [1995] A Material Model for a Ceramic Powder Based on Ultrasound, TRS Bend Bar, and Axisymmetric Triaxial Compression Test Results (ASME, New York), pp. 57–68, and (iv) validate, to some extent, the results provided by the kinematic approach.

Experimental Study on Performance of Pressure Sensor and Similar Material Model

2010 ◽  
Vol 163-167 ◽  
pp. 4537-4541
Author(s):  
Shao Jie Chen ◽  
Bo Li ◽  
Wei Jia Guo
Keyword(s):  
Mechanical Properties ◽  
Pressure Sensor ◽  
Pressure Sensors ◽  
Material Model ◽  
Repeated Loading ◽  
Pressure Curve ◽  
Test Results ◽  
Similar Material ◽  
Matching Problem ◽  
Similar Materials

In this paper, in order to get the mechanical properties of the different ratio similar material models and resolve the matching problem of pressure sensor and measured similar material, according to the similarity theories, the repeated loading tests on different ratio similar models were performed by multi-stage loading. This paper got the stress-pressure curve and the failure strength of each model. Test results show that there are significant differences in the matching abilities between different ratio similar materials and pressure sensors, and the matching abilities between different models of the same ratio and pressure sensors also have some differences. The matching ability between similar material and pressure sensor should be detected, so as to correct the experimental data. Test results also show that different ratio similar materials have stable and different mechanical properties. The mechanical properties of the similar material can be adjusted appropriately by changing the ratio. The mechanical properties of different ratio similar materials should be tested before the similar material simulation test.

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