MINISTRY OF EDUCATION AND TRAINING
HANOI UNIVERSITY OF MINING AND GEOLOGY
……………………….
PHAM VAN CHUNG
RESEARCH ON BUILDING THE GEOMECHANICAL CHANGING
MODEL OF MECHANIZING WORKING FACES IN THE THICK
SEAM OF COAL MINES IN QUANG NINH
Major: Geodesy – Mapping
Techniques Code: 9520503
SUMMARY OF DOCTORAL DISSERTATION ON TECHNOLOGY
Hanoi - 2018
The dissertation was completed at the Department of Mine Surveying, Faculty
of Geomatics and Land Administration, Hanoi University of Mining and GeologyBộ
môn Điện khí hóa, Khoa Cơ-Điện, trường Đại học Mỏ-Địa chất.
Full name of scientific advisors:
1. Assoc. Prof. Dr Phung Manh Dac
2. Dr Vuong Trong Kha
Reviewer 1: Assoc. Prof. Dr Nguyen Xuan Thuy
Reviewer 2: Assoc. Prof. Dr Kieu Kim Truc
Reviewer 3: Dr Nguyen Ba Dung
The thesis will be defended to the University Examination Committee at
Hanoi University of Mining and Geology
At………………………….2018
The hard copy of the thesis could be found at the following libraries:
Vietnam National Library,
The library of Hanoi University of Mining and Geology
ườại học Mỏ - Địa chất
1
INTRODUCTION
1. The necessity of the thesis
The characteristics of rock displacement at the face employing the
machine - based exploiting method of thick seams depend on several
factors such as the status of seams, the characteristics of surrounding
rocks and exploiting technologies. As the development of information
technology, the computer based models like the geo-machenical one
help to illustrate the characteristic of rock displacement. The main
feature of geo-machenical model is: (i) modeling the 3D homogeneous
and continuous environment of rocks, or heterogeneous one through the
deformation of environment, (ii) Use the initial stress state of the soil as
a boundary condition (iii) The trigger of stress state is the exploit space
that is characterized by geometric parameters in three dimensions.
At present, in some mines in Quang Ninh such as Khe Cham have
used the machine - based exploiting method. The method of lowering
the roof coal recovery for thick seams has created large gaps.
From the aforementioned review, PhD thesis topic: " Research on
building geomechanical changing model for faces employing the
machine - based exploiting method of thick seams in several
underground coal mines in Quang Ninh" was selected Derived from
practical needs and practical significance.
2. Research objectives of the thesis
2.1 Research objectives
To form the scientific basis and methodology to build the model of
geomagnetic changes to determine the laws of rock and soil
stratigraphic deformation due to the effect of the mechanized pelletizing
market on the exploitation of thick seams in some underground coal
mines in Quang Ninh.
2.2 Tasks
To achieve the above objectives, the research must perform the
following tasks:
- An overview of mine geomechanical models;
- Studying the geological conditions, machenical and physical
properties of the Quang Ninh coal mines in the condition of thick seam;
- To study the scientific methodology of building the
geomechanical change model;
2
- To study the determination of boundary conditions for the
geomechanical change model through the processing of field
observation data;
- Applying the geomechanical change model to determine the rule
of displacement and deformation while exploiting thick seams by
mechanizing working method, applied to the Nam Mau mine.
3. Objects and Scope of the thesis
3.1. Subjects
The subject of study is the displacement and deformation of gound
surface and the collapse of wall when exploiting thick seams by
mechanizing working method.
3.2. Scope of the study
Nam Mau underground coal mine, Quang Ninh province.
The study investigates the correlation between the maximum
subsidence and elastic parameters of the rock mass through the
application of geomechanical change model to predict displacement and
deformation.
4. Methodologies used in the thesis
- Field Observation: conduct monitoring stations for displacement
in the Quang Ninh coal mining region to verify the accuracy of the
geomachenical model and building standard curve functions for this
region;
- Theoretical method: Based on the numerical method, using the
finite element method to solve the problem of the geomachenical model
- Method of collecting, analyzing and synthesizing for the thesis
overview;
- Statistical regression method: Determine the relationships
between elasticity parameters and maximum subsidence;
5. The dissertation main points
Point 1: The standard curve function constructed using the data of
field observations in some coal underground mines allows to determine
the size of ground areas affected by subsidence, to calculate the
displacement, and to forecast the safe depth of exploitation of coal
mines in Quang Ninh.
Point 2: The building or geomachenical model is based on the
relationship between the elastic modulus and the maximum subsidence
3
on the surface determined using the data of the field observations, which
allows to study the discipline of deformation and destruction of rocks in
both strata and ground.
6. The dissertation new features
- For the first time in Vietnam, the thesis has constructed the
standard curves S (z), F (z), F '(z) for predicting the displacement and
deformation of rocks in the Quang Ninh coal basin.
- The thesis determines the relationship between the rock elastic
modulus and the maximum subsidence on the surface determined using
the data of the field observations.
- The study has determined the coefficient of durability K = 1,24 to
build geomachenical model of Quang Ninh region in order to predict the
displacement and deformation as well as destruction of rocks and
ground surface.
- The thesis has identified the law of displacement, deformation and
destruction of the walls at faces that using the machenizing exploitation
and roof coal extraction method in the V7 seam of the Nam Mau mine.
7. Scientific and practical significances
7.1. Scientific significances
Set up a scientific basis and methodology to develop geomachenical models with homogeneous or heterogeneous environments
of rock masses to predict the displacement and deformation of rocks
when exploiting thick seams by the machenizing method.
7.2. Practical significances
- Application of geomachenical model allows to investigate the
influence of mechanical parameters on elastic parameters and the
thickness of coal seams.
- The model allows to forecast the displacement and deformation
of not studi mines not thoroughly studied on deformation shifts.
8. Data
Data for the study was collected through field obseravation stations
in the Quang Ninh coal basin
9. Structure of thesis
The thesis consists of five chapters, introduction, conclusion, and
references which are written on 128 pages of A4.
Chapter 1: an overview and theoretical basis for research on
4
displacement and deformation of strata and ground surface due to
underground mining
Chapter 2: reseach on the displacement and deformation of strata
and ground surface due to underground mining using geomachenical
models
Chapter 3: research on building standard curve fuctions using the
data of observation stations in underground mines in quang ninh
Chapter 4: research on the relationship between maximum
subsidence and elastic modulus of mine rock mass
Chapter 5: application of geomachenical model on research on the
principle of displacement and deformation of strata and ground surface
due to excavation of v7 seam in the nam mau mine in quang ninh
Conculsions and Recommendations
Publication
References
CHAPTER 1
AN OVERVIEW AND THEORETICAL BASIS FOR RESEARCH ON
DISPLACEMENT AND DEFORMATION OF STRATA AND GROUND
SURFACE DUE TO UNDERGROUND MINING
1.1. Literature review about research on the geomachenical model
in the world
In the world there are many studies using numerical methods:
1. There are some researchers such as A.B Fadeev, Vitke, S.G
Ashikhmin who solved the problem of continuous environmental
mechanics.
2. There are some researchers such as A. D. Xashurin, V. E.
Bolicov, A. B. Makarov who solved the problem of elastic and
continuous environmental model in the works of researchers [23, 27, 52,
56, 57].
3. There are scientists A.B. Makarov, V.N. Boris - Komponees
who calculated the parameters of the movement process when
exploiting thick coal seams.
4. The M.V. Kurlen, A.B. Fadeev and others have made important
contributions to the development of nonlinear deformation models of
the rock mass [37, 42, 72].
5. For the first time the numerical method used by Kratch [48] is
5
used to calculate the rock mine prediction in the case of slope coal
mining with the elastic medium model.
T2
2
1
3
T1
5
4
Figure 1.3: Geomachenical model by Xashurin used to analyze the
deplacement of rock
1.2 Literature review about research on the displacement and
deformation of rocks in the Quang Ninh mining region
In Vietnam, from 1980 to 2010, the displacement and deformation
of rocks in mining areas did not received attention:
In 1980, Assoc Prof Nguyen Dinh Be [1] was the first Vietnamese
scientist who researched on the displacement and deformation of rocks
due to underground mining in Vietnam.
Followed by Prof Vo Chi My [14], Dr Nguyen Xuan Thuy Dr Kieu
Kim Truc [21], and Dr Vuong Trong Kha [13]. From 2002 to 2007, the
Institute of Mining Science and Technology - TKV conducted the
construction of monitoring stations and field observation at the state
level led by Dr. Phung Manh Dac and Pham Van Chung [7].
In the period from 2010 to present, some scientists have used
theoretical methods using numerical methods such as Dr. Nguyen Anh
Tuan (2011) and his team used the Phase 2 program to analyze
subsidence and mechanical changes in both underground and open pit
mining.
In 2014, Dr. Le Van Cong applied the numerical model to
determine the parameters of displacement and deformation during
6
excavation and exploitation at mines in Quang Ninh using the FLAC 2D
software.
In 2015, Prof. Dr. Nguyen Quang Phich applied and developed an
analytical model for forecasting geological hazards for underground
works and mining projects in Vietnam.
1.3 Conculsion of chapter 1
1. Geomachenical models with outstanding advantages includes the
ability to build models from simple to complex as well as flexible in the
selection of model parameters that other research methods do not have.
Also, with the rapid development of numerical methods and numerical
tools that are being prioritized to solve problems related to ground
displacement and deformation due to underground mining.
2. In Vietnam, up to now, there have been some researches on
predicting the displacement and deformation of ground surface due to
underground mining by the method of equivalent material model,
conducted by Nguyen Dinh Be, Mining Technology Institute - TKV and
Department of Mine Surveying, University of Mining and Geology.
These are initially results, but there are some limitations such as the
inability to create similarities between physical and model indicators,
model ratios too small compared to The actual range and results
obtained are only qualitatively quantifiable, quantifiable. In fact, there
have been some results of studying the deformation by geomachenical
model of authors such as Prof. Dr. Nguyen Quang Phich and Dr. Le Van
Cong. However, these results are applicable in underground
construction and oven way. Clearly, the problem of studying the
deformation of soil and rock stratigraphy by the impact of mining is an
open topic in the context of Vietnam.
3. The results of field observations allow to accurately determine
the parameters and magnitude of deformation shifts on the soil surface
of an area due to the impact of pit mining, but there are also certain
limitations. It is impossible to describe the overall picture of the rocky
rock deformation process. Therefore, it is necessary to study the
combination of two methods: theoretical method based on numerical
methods and field observation method to complement each other allows
to study the overall picture of the process of moving deformation of the
rock as well as pressure control of mine to have safe and effective
mining solutions
7
CHAPTER 2
RESEACH ON THE DISPLACEMENT AND DEFORMATION OF
STRATA AND GROUND SURFACE DUE TO UNDERGROUND
MINING USING GEOMACHENICAL MODELS
2.1 Overview of geomachenical model
2.1.1 Definition
First of all, it is easy to understand that a model is an unclear
representation of reality. This can be made of material or completely
abstract by theory.
2.1.2. Features of model
According to Herbert Stachowiak, a model is characterized by at
least three characteristics [46]:
(1) Copy, (2) Narrow, shrink. (3) Practicality
2.1.3. Classification of model
1. Model of experience, 2. Analytical model, 3. Digital model
2.1.4. Advantages and disadvantages of model
- Experience model simulating simple geological and mechanical
factors. So only qualitative results
- Analytical model: with mathematical functions usually for
closed-loop, accurate results. However, this limitation model usually
only solves the simple assumption that the elastic soil, isotropic, does
not pay attention to stress,
- Model Number: Simulate all the characteristics of the soil and
change the input parameters quickly to give consistent results.
Therefore, the complex solution, the rocky environment is not the same
everywhere, so simulation is difficult.
2.2. Study using the model
2.2.1 Building model
a) Geology
b) Geo-technique
Figure 2.1: Building the model
c) Technique
8
2.2.2 Study on the model
Modeling studies mean finding a way to reproduce what might be
affecting a physical object, to obtain signals or information in the
desired way of the researcher.
2.2.3. Model validation
The results of the model study, or simulation results, will be of
practical significance when those results are tested to demonstrate on the
real object, in this case the rock around the mining space.
2.2.4. Adjust the parameters of the model
In the event of a deviation, the next task is to redefine the input
parameters through the reverse analysis problem for the theoretical
models (theoretical models), or to adjust the coefficients of
Experimental functions, parameters or experi- ences for mathematical
models (or semi-empirical models)
2.3 Mine geomorphology model for rock deformation analysis
2.3.1. History of research on geo-model
In order to study and explain the laws of rock deformation
prepared by excavation as well as coal mining in the market furnace, a
simple geomachenical model for a cubic cubic spring. The rock unit in
depth H is shown in Figure 2.3. The boundary condition of this model is
that of the normal stress components σ1 and the stresses σ2, σ3 with the
following values defined as [2]:
P = 1 = H
(2.1)
2 = 3 = k1.
(2.2)
σ3
σ1
σ2
σ2
2
σ1
σ3
Figure 2.3. Simple geomachenical model with stress
vector at the depth of H
9
Based on the above model, we explain the rules for shear
modulation when preparing the furnace (Figure 2.4) and when mining
coal in the market (Figure 2.5).
Kratch [48] overcomes some drawback of the above model by
introducing geo-turbulent models (Figure 2.6).
Figure 2.6. Plan of distribution of soil and stone in the working tunnel
2.3.2. Systemizing the geomachenical model of rock
2.3.3. Modern conception of geomachenical model
2.3.4. Parameters on the geomachenical model
2.3.5. Distortion and structure of geomachenical model
2.3.6. Boundary conditions in mine geomachenical environment
2.3.7. Patterns of geomachenical model for the prediction of
displacement and deformation
2.4 Selection of geomachenical models for Quang Ninh coal basin
conditions
- Model with elastic, homogeneous, isotropic environment.
- This model is solved by finite element method
- Input data of the model are mechanical parameters, geometrical
dimensions, thickness of the reservoir such as: Compressive strength σ
of soil types, geological durability index (GSI), explosion damage index
(D), the material constant (m ii) to determine the elastic parameters E.
The geometry dimensions such as the depth of exploitation, the length
of the furnace market in the direction and the direction of the slope.
- The results of field observation determine the standard curvature
of Quang Ninh coal basin for deformation prediction.
The software dedicated to solving the problem is Rockdata, R and
Rocscience 2.0.
2.5 Conculsion of chapter 2
10
1. Based on the analysis of different geomachenical models and
numerical methods, the student selects the isotropic elastic model and
finite element method (FEM). This choice is based on the published
research results and the specific context of the research conditions
(actual data, calculation tools and research experience).
2. When applying this geomachenical model in practice, to avoid
constraints (the subjective approach when dividing the mass into finite
elements, the stabilization of rocky physical properties, the number
restriction of elements, to simulate an intermittent or intermittent elastic
environment, the model becomes cumbersome and complex), it is
important to study the geodetic modulation accordingly. provided that
the study area is characterized by field observation data.
CHAPTER 3
RESEARCH ON BUILDING STANDARD CURVE FUCTIONS USING
THE DATA OF OBSERVATION STATIONS IN UNDERGROUND
MINES IN QUANG NINH
3.1 Method of monitoring and data processing
At present, techniques and methods of monitoring, displacement
and deformation of ground surface range from traditional to modern
ones. There are many different methods of observation such as high
accuracy ground observation method, aerial photogrammetry and GNSS
monitoring system [12].
3.2 Methodology for the construction of standard curve functions
Analytical graph method is based on the use of standard curve of
distribution of subsidence and deformation in the trough subsidence.
The origin of the coordinates usually takes the point of maximum
subsidence (Figure 3.1).
Figure 3.1. Actual subsidence curve and dimensionless subsidence curve
11
Based on the theory of standard curve function, the values of
standard curves S (zx), F (zx), F '(zx) are defined for Quang Ninh.
3.3 Determine parameters and displacement factors
3.3.1. Theoretical basis for determining the parameters for the less
studied rock mine site
a. Determination of stratified solidification coefficient
b. Selection of mine groups based on the feldspar solidification
factor f.
3.3.2. Determination of parameters and displacement quantity
3.4 Define the standard curves of the Quang Ninh area
Selling actual displacement tank is divided into 10 parts, at each
divided point, the subsidence values of i, slope ii, curvature must be
calculated. Horizontal displacement i and horizontal deformation i.
The distribution function of the subsidence, tilt, curvature, horizontal
displacement and horizontal deformation are defined as the following
derivatives [23]: (3.29)
Table 3.16 Standard curve functions
N0
0
1
2
3
4
5
6
7
8
9
10
S(z)
-1,00
-0,90
-0,76
-0,51
-0,30
-0,20
-0,13
-0,09
-0,06
-0,04
0,00
S’(z)
0,12
0,88
0,06
2,39
0,33
0,88
0,59
0,42
0,19
0,78
0,04
S” (z)
3,19
-0,68
1,70
-9,83
14,08
2,08
2,64
0,74
1,11
-6,33
1,40
F(z)
4,59
4,29
3,47
2,55
2,71
1,91
1,14
0,97
0,80
0,89
0,02
F’ (z)
-2,40
6,87
0,83
6,80
5,53
2,54
1,78
0,61
0,61
0,86
-0,12
12
Table 3.17 Standard curve functions
N0
S(z)
S’(z)
S” (z)
F(z)
F’ (z)
0
-1,00
3,11
-62,69
6,75
-14,34
1
-0,61
4,10
-15,80
4,15
-13,28
2
-0,37
2,78
25,53
2,92
-12,96
3
-0,27
0,89
24,87
1,69
-13,53
4
-0,23
0,06
-21,68
1,60
-5,01
5
-0,22
-0,05
6,57
1,95
-2,63
6
-0,20
0,15
14,17
2,17
-0,11
7
-0,19
0,16
-0,59
1,90
-6,67
8
-0,14
-0,01
1,35
1,26
5,88
9
-0,08
0,54
-1,61
0,65
2,41
10
0,00
0,00
0,00
0,00
0,00
3.5 Conculsion of chapter 3
1. The methods used to calculate the deflection parameters and the
standard curve functions are reliable and have been widely used in many
countries around the world. Thus, from the above results have
determined the geometric dimensions of the geomachenical model, the
angle of displacement of the model, determine the maximum one-sided
subsidence allows to forecast the rock deformation shift for Vietnam,
On the other hand, establish the boundary conditions for the
geomachenical model.
2. Analysis, processing and synthesis of field observations of Mao
Khe and Mong Duong coal mines have defined the standard curve
functions S (z), F (z), F '(z) Compared with the geological and mining
conditions of the Quang Ninh coal basin for the purpose of calculating
forecasts of surface deformation changes in order to protect the works
and ensure the safety of the exploitation process coal pit
CHAPTER 4
RESEARCH ON THE RELATIONSHIP BETWEEN MAXIMUM
SUBSIDENCE AND ELASTIC MODULUS OF MINE ROCK MASS
4.1 Construction of geomachenical model for rocks in the Quang
Ninh coal basin
4.1.1. General geological characteristics of study area
Quang Ninh coal basin consists of three areas [8]: Uong Bi, Hon
Gai amd Cam Pha with different geological conditions:
Experimental results of rock samples by single-axe compressing
method in Quang Ninh coal basin are shown in Table 4.1 [8]
13
Table 4.1: Experimental results of single-axis compression tests of rocks
No
Typle of
σ (Mpa)
stone
1
Sandstone
114
2
Siltstone
42
3
Claystone
31
4
Coal
17.1
4.1.2. Determination of elastic modulus for rock layers in Quang Ninh
coal basin
4.1.3. The results of the elastic modulus E according to Rockdata
To calculate the E modulus of the Rockdata, input parameters such
as one-axis compression strength (σ), geological durability index (GSI),
mine explosion indices (D), GSI, D index are based on the experience of
expert such as Ngo Van Sy. The input data recorded in Table 4.5, the
results of the elastic coefficient E are shown in Table 4.6
Table 4.5: RocData input
STT Typle of
σ
GSI
Destructive
Material
stone
MPa
parameters
constant
(D)
(mi)
1
Sandstone
114
45
0.8
17
2
Siltstone
42
37
0.8
7
3
Claystone
31
11
0.8
4
4
Coal
17.1
8
0.8
4
Table 4.6 Estimation of elastic modulus E by Hoek - Brown
No
Typle of
stone
σ
GSI
Destructive
parameters
(D)
Material
constant
(mi)
Elastic
Modulus E
(Mpa)
1
Sandstone
114
45
0.8
17
2115
2
Siltstone
42
37
0.8
7
691.36
3
Claystone
31
11
0.8
4
244.03
4
Coal
17.1
8
0.8
4
93.01
14
No
1
2
3
4
5
4.2 Calculation of rock and soil stratigraphic shifts
4.2.1 Overview of RS2 (Phase2) software from Rocscience Inc.
(Canada)
4.2.2. Input parameters and calculation cases
TH1: Building the model with the elastic modulus of sandstone E =
2115 MPa, silage with E = 691.36 MPa, clay with E = 244.03 MPa
calculated from Rocdata, Poisson coefficient ʋ no change
TH2: Input parameter is 70% elastic coefficient calculated from
Rocdata, Poisson coefficient ʋ is constant
TH3: Input parameter is 50% elastic coefficient calculated from
Rocdata, Poisson coefficient ʋ is constant
TH4: Input parameter is 125% elastic coefficient calculated from
Rocdata, Poisson coefficient ʋ is constant
TH5: Initial parameter and equal to 30% elastic coefficient
calculated from Rocdata, Poisson coefficient ʋ is constant
TH6: Input parameter is 10% elastic coefficient calculated from
Rocdata, Poisson coefficient ʋ is constant.
4.2.3 Calculating results for the case in the slope direction of face
From Table 4.7, the larger elastic modulus of elasticity are the smaller
subsidence is, so the correlation coefficient is high.
Table 4.7 Maximum subsidence value and elastic modulus
Typle of
Result of subsidence and elastic modulus
Value
stone
TH1
TH2
TH3
TH4
TH5
TH6
Sandstone
Siltstone
Claystone
Coal
E(MPa)
2115.00
1480.50
1057.50
2643.75
634.50 211.50
E(MPa)
691.36
483.95
345.68
864.20
207.41
69.14
E(MPa)
244.03
170.82
122.02
305.04
73.21
24.40
E(MPa)
93.01
93.01
93.01
93.01
93.01
93.01
Ƞ(m)
1.906
1.500
1.918
0.944
2.658
5.095
15
Figure 4.5: Chart of subsidence of strata Figure 4.6: Chart of subsidence
in case 1
in case 1
4.3 Determine the relationship between maximum subsidence and
elastic modulus
4.3.1 Statistical analysis methods
4.3.2 Linear regression method
4.3.3 Determine the relationship between maximum subsidence and
elastic modulus
To evaluate the importance of influencing variables, use the
statistical and graphical analysis language (R software) to determine the
correlation and independent variables.
The database is taken from Table 4.7, the analysis results are as
follows:
For sandstone, siltstone, claystone we have the correlation diagram
shown in Figure 4.17 and 4.18.
5
neta
4
3
2
1
250
500
750
E
Figure 4.17. The chart shows the Figure 4.18. The chart shows the
correlation between elasticity and correlation between elasticity and
maximum subsidence of siltstone
maximum subsidence of sandstone
16
The equation shows the relationship between maximum subsidence
and elastic coefficient of rocks:
ƞ= a+ EX+EX2+ EX3
Based on this, the correlation between the sandstone and its
elasticity was determined using Equation 3.4
Ƞ= 7.01 - 1.04.10-2. E + 6.50.10-6. (E)2- 1.30.10-9. (E)3
(4.4)
Equation 3.5 for siltstone
Ƞ= 7.01 - 3.17.10-2. E + 6.08.10-5. (E)2 - 3.72.10-8. (E)3
(4.5)
Equation 3.6 for claystone
Ƞ= 7.01 - 8.99.10-2. E+ 4.88.10-4. (E)2 - 8.46.10-7. (E)3
(4.6)
Thus, the equations (4.4), (4.5), (4.6) determine the elastic
coefficient EC as shown in Table 4.8.
Table 4.8 Results of elasticity coefficient of rocks
No
Coefficients
Sandstone
Siltstone
Claystone
1
ER
2115
691.36
244.03
2
EC
2628.788
860.368
303.637
Note
The results of Table 4.8 show that if the elasticity coefficient
calculated on the Rockdata (ER) software is included in the
geomachenical model for any given area, this can be used to predict
surface deformation. The parameters are based on offering safe and
effective exploitation solution. During data processing, however, using
the geomachenical model for Quang Ninh coal basin, the coefficient of
durability is determined by the formula 4.7.
KC = EC/ER=1,24
(4.7)
4.4 Conculsion of chapter 2
1. In the world, there have been many geomachenical models for
analyzing and forecasting displacement and deformation of land surface,
and they are developed in different forms. Existing models have certain
disadvantages and are often local and related to specific geological
conditions of each region and country. Geomachenical models are a
quantitative method. The accuracy of the models depends on a number
of factors, including the one-axis compression test
2. In practice, the study of land surface deformation due to
underground mining, the study using the geomachenical model with the
initial data of the Quang Ninh coal basin has identified the elastic
modulus for geomachenical models with boundary conditions of the
17
model is the maximum subsidence determined by the field observations,
the geomachenical model has been adjusted more closely. The author
builds a geomachenical modelfor scientific analysis, forecasting,
displacement and surface deformation. For the geo-model applied to
Quang Ninh coal basin, coefficient of durability reduction is KC = 1,24.
CHAPTER 5
APPLICATION OF GEOMACHENICAL MODEL ON RESEARCH ON
THE PRINCIPLE OF DISPLACEMENT AND DEFORMATION OF
STRATA AND GROUND SURFACE DUE TO EXCAVATION OF V7
SEAM IN THE NAM MAU MINE IN QUANG NINH
5.1 Study area
The study area where the monitoring stations were placed with the
coordinates of boundary showed in Table 5.1 [7].
Table 5.1: Coordinates of boundary of monitoring area
Points
X
Y
(m)
(m)
A
40400
368900
B
40400
370300
C
39100
368900
D
39100
370300
5.2 Overview of excavation method
Technology for exploitation is the exploiting long columns in
faces. This technology is proposed to apply to thick and sloping
conditions as shown in Figure 5.3 [9]. Characteristics of technology of
exploiting thick seams are the rate of loss of coal will increase by the
thickness of the lower layer of coal.
Figure 5.3: the diagram of machenized long wall exploitation, extracting
roof coal at faces [9]
18
No
5.3 Proposed elastic parameters for model of Nam Mau coal mine
During the geotechnical construction work, apart from the samples
taken at the V-lines, LK-24, LK-NM20, LK-NM51, LK-36, LK-38A,
LK-38, LK-NM20 route LK-CG16, LK-NM27, LK-CG17, LK-NM28
route III
Table 5.3 Results of determination of E, C, φ in Nam Mau coal mine
according to Rockdata
Typle of
σ
GSI Destructive Material Elastic Sticky Internal
stone
parameters constant Modulus force friction
(D)
(mi)
E (MPa)
C
angle φ
(MPa)
(độ)
1
Sandstone
114
45
0.8
17
2115
0.807
42.358
2
Siltstone
42
37
0.8
7
691.36
0.324
23.276
3
claystone
31
11
0.8
4
244.03
0.41
12.281
4
Coal
17.1
8
0.8
4
93.01
0.059
3.5
Thus, the results of determination of the parameters E, C, φ input
to run for geomachenical model and calculation with plastic elastic state
of Nam Mau Quang Ninh coal mine is shown in Table 5.4.
Table 5.4: Result of determination of E, C, Nam Nam Mau coal mine
No Coefficients Sandstone Siltstone claystone
coal
Note
1
EC
2628.788
860.368
303.637 93.01
2
C
42.358
23.276
12.281
3.50
3
φ
0.807
0.324
0.41
0.059
5.4 Calculate the deformation shift when mining the motorized
market in the direction of the slope on the geomachenical model
The geodatabase model developed in Chapter 4, the input
parameters in the computation process is the E, C, and giá values
provided by the Rocscience 2.0 commercial software. The calculated
area of the model is 700x300m from the actual width of 1400x450m,
but the area of the reservoir 7 is limited from the LK7 hole to the outer
border of 500m. Exploiting reservoir 7 from -80 to the ground is 250m,
ie the height is about 330m. Therefore, the study model is 700x300 is
reasonable real.
- Xem thêm -
.PDF 
28 
129 
59 
