Academic Journal of Science and Technology 
ISSN: 2771-3032 | Vol. 11, No. 1, 2024 

 

205 

Study	on	Reinforcing	Anchor	Cable	Support	in	
Overreach	Section	of	Deep	Roadway	
Binbin Wang1, *, Xinchen Wang2, a 

1School of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo, China 
2Technology Institute of Energy Engineering, Shanxi Institute of Science and Technology, Jincheng, China 

*Corresponding author: 1533199013@qq.com, a3198577348@qq.com 

 

Abstract: With the increasing depth of coal mining, the conditions of deep working face are becoming more and more complex, 
the stability of surrounding rock of roadway is getting worse and worse, and the problem of deep roadway support is becoming 
more and more prominent. In this paper, the 24100 working face of Pingdingshan No.11 Coal Mine is taken as the engineering 
background. In view of the problems of roof crushing and deformation and more net pockets in the return airway affected by the 
mining of the working face, the grouting anchor cable reinforcement and support technology in the advance section of the deep 
mining roadway is proposed, and the feasibility of the support effect is verified by numerical simulation. The results show that 
the influence range of the advance abutment pressure of the air roadway is about 60 m, and the reinforcement support strength 
required for the roof of the roadway is 50.6 kN/m2. The grouting anchor cable reinforcement support technology system of the 
return air roadway can control the deformation of the surrounding rock of the roadway and achieve safe and efficient mining. 

Keywords: Advanced Support Technology; Grouting Anchor Cable; Active Support; Deep Roadway; Numerical Simulation. 
 

1. Introduction  
At present, the reserves of coal seams with ' superior ' 

occurrence conditions are becoming less and less. In order to 
meet the needs of energy and achieve the goal of sustainable 
development, it is necessary to mine deep coal seams with 
complex burial conditions. The proportion of deep mines is 
increasing year by year[1]. Due to the special environmental 
conditions of deep mine, such as high ground stress, high 
temperature, rich groundwater, etc, the soft rock roof expands 
and cracks develop after roadway excavation, and the stability 
of roadway surrounding rock itself is poor[2]. For the deep 
mining roadway, on the one hand, under the complex stress 
environment, the roadway is greatly affected by the mining 
disturbance of the working face, the mine pressure appears 
frequently, the cracks in the surrounding rock of the roadway 
are further expanded and developed, and the plastic zone of 
the surrounding rock continues to increase. On the other hand, 
the occurrence of coal seams is mostly soft rock inclined coal 
seams. At the same time, affected by the inclination of 
inclined coal seams and the structure of coal and rock mass, 
the surrounding rock of roadway is prone to stress 
concentration, which leads to frequent asymmetric 
deformation and failure of roadway roof, floor and two sides. 
Many field practices show that [3]-[4], Fully grasp the 
distribution of advanced abutment pressure and the 
deformation law of roadway surrounding rock under the 
influence of mining, and put forward a targeted technical 
scheme for strengthening support and control of surrounding 
rock, so as to avoid the situation of " excavation before repair 
" in the roadway, improve the stress state of surrounding rock, 
and realize the safe and efficient mining of the mine.  

According to the existing research and field practice, it 
shows that[5]-[6], The bolt-grouting support technology formed 
by grouting anchor cable and bolt can play a good supporting 
effect on the advance support of mining roadway. At present, 
this method has made some technical progress, but it still 
needs to be further studied and solved in terms of selecting 

suitable slurry materials, determining the best grouting 
parameters, layout and design of grouting anchor cables.  

2. Description of the Mine Study Site 
The No.11 mine is located at the foot of Xiangshan in 

Pingdingshan City, Henan Province. The east-west direction 
of the mine is 6.6 km long, the north-south inclination width 
is 2.54 km, and the mine field area is 13.6252 km2. The Ⅶ 
of the 16-17-24100 working face is −784.2 m ~ −872.1 m, the 
corresponding ground elevation is +130.00 m ~ +147.00 m, 
and the average dip angle of the coal seam is about 13.0 °. The 
16-17 coal is black massive and granular, mainly composed 
of bright coal, with a thickness of 2.0 m ~ 7.0 m, an average 
thickness of 5.3 m, and a thin layer of gangue with a gap of 
0.06 m. The immediate roof is about 1.0 m ~ 3.5 m mudstone 
and sandy mudstone, the basic roof is about 7.0 m ~ 13.0 m 
sandstone and sandy mudstone, the direct bottom is 2 m ~ 5 
m thick gray black massive mudstone, and the basic bottom 
is 8 m ~ 15 m thick sandstone and limestone. 

Based on the geological conditions of the coal seam where 
the 24100 working face is located, the basic quality index of 
the rock mass and the mechanical parameters of the coal and 
rock, the geomechanical evaluation of the surrounding rock 
of the 24100 roadway is carried out. The factors that have a 
great influence on the deformation of the surrounding rock of 
the roof in the advanced section of the 24100 working face 
mainly include the soft rock of the roof and floor, the 
development of the roof fissure, the water filling of the roof 
sandstone fissure, the influence of the mining and the stress 
of the deep high surrounding rock. The mine pressure of the 
roadway in the advanced influence area of the working face 
is severe, the roof crushing phenomenon is serious, the 
displacement of the mining side invading the roadway is large, 
and there is a great potential safety hazard. It is necessary to 
further strengthen the control of the surrounding rock of the 
roadway in the advanced section. 



 

206 

3. Grouting Anchor Cable 
Reinforcement Support Technology 

3.1. Mechanical analysis of surrounding rock 
of roadway 

The application of grouting anchor cable support 
technology in roadway can significantly improve the overall 
mechanical properties of surrounding rock, realize the 
consolidation effect by filling the fracture of surrounding rock 
with slurry, effectively control the development of 
surrounding rock loose circle, prevent the weathering of rock 
stratum and transform passive support into active support. 
The radius of the plastic zone of the roof of the roadway can 
determine the failure depth of the surrounding rock of the roof 
and the support range of the anchor cable. The anchor cable 
connects the soft and unstable rock mass of the lower layer 
with the complete rock mass of the upper layer to form a 
unified anchor solid, which controls the deformation of the 
surrounding rock of the roadway and prevents the plastic zone 
of the surrounding rock from continuing to expand. The 
surrounding rock structure of the roof of the inclined roadway 
is shown in Figure 1. 

 

 
Figure 1. Mechanical structure of roadway roof surrounding 

rock. 
	
Based on the suspension theory, the supporting strength 

that the anchor cable needs to provide is : 
 

𝑃 𝑑𝜃

𝑥 𝑑𝑥   (1) 

 

𝜃 𝑎𝑟𝑐𝑐𝑜𝑠     (2) 

 

𝜃 𝑎𝑟𝑐𝑐𝑜𝑠     (3) 

 

In the above formula: R1 and R2 are the radius of plastic 
zone corresponding to θ1 and θ2. The calculation results are 
6.05 m and 6.15 m; The height of low side and high side of 
roadway b1 and b2 is 2.9 m and 4.1 m respectively. a is 5.2 m. 
It is calculated that the support strength required for the static 
load state of the roof per unit area is 125.67 kN/m2. 

The supporting strength required under the influence of 

mining is: 
 

𝑝 𝐾𝑝 𝑘                  (4) 

 
In the above formula, K is the stress concentration factor, 

taking 1.92 ; k1 is the safety factor, take 1.2. It is calculated 
that the support strength required for the roof per unit area 
under the influence of dynamic pressure is 289.5 kN / m2. 

According to the suspension theory, the supporting strength 
of the original supporting bolt roadway is: 

 

𝑃               (5) 

 
In the above formula: Pt is the original support anchor cable 

roadway support strength, kN/m2; F is the pre-tightening 
force of anchor rod and anchor cable, which is 150 kN and 
200 kN respectively. n is the number of anchor bolts and 
anchor cables, taking 7 and 3; L1 and L2 are the spacing of 
anchor bolts and the row spacing of anchor cables, taking 0.78 
m and 0.75 m respectively, and the minimum values of anchor 
bolts and anchor cables are taken from the original support 
design. ω1 and ω2 are the support efficiency of the anchor rod, 
respectively, 0.7 and 0.75 according to the actual situation and 
related literature. 

It is calculated that the supporting strength of the roadway 
roof per unit area of the original supporting bolt is 
238.9kN/m2. The required strengthening support strength of 
the roof advance section of the return air roadway in the 
24100 working face is not less than 50.6kN/m2. 

In order to further study the advanced stress distribution 
and surrounding rock deformation law of the return air 
roadway under the original support, taking the return air 
roadway of 24100 working face as the research object, the 
FLAC 3D model software is used to simulate the original 
support method, which provides a reliable basis for the 
reinforcement and support technology of grouting anchor 
cable in the return air roadway. 

3.2. The distribution law of advance abutment 
pressure 

3.2.1. Modeling 
Taking the return air roadway of 24100 working face in 

No.11 Coal Mine as the engineering background, FLAC3 D 
software was used for research. The dip angle of the coal seam 
is 13 °, the average thickness of the coal seam is 5.3m, and 
the length of the 24100 working face is 297.8m (the model is 
300m). X×Y×Z=400 × 400 × 130. The FLAC3D numerical 
model is established, as shown in Figure 2. 

 

 
Figure 2. Numerical calculation model diagram. 



 

207 

The Mohr-Coulomb constitutive model is selected for the 
simulation study. The buried depth is 1000 m. In order to 
simulate the self-weight of the overlying strata, a vertical 
stress of 25 MPa is applied at the top of the model. The 
pressure coefficient is 1.1. The z direction of the top of the 

model is set as the free surface, and the other surfaces are 
fixed. The physical constraints of the model are shown in 
Figure 3. The mechanical parameters of coal rock are 
obtained according to the field drilling core experiment, as 
shown in Table 1. 

 

 
Figure 3. Physical constraint diagram of the model. 

 
Table 1. Coal rock mechanics parameter table. 

lithologic characters 
bulk modulus 

/GPa 

shear 
modulus 

/GPa 

force of 
cohesion /MPa 

angle of internal 
friction /(°) 

tensile 
strength /MPa 

density 
/(kg/m3) 

Sandy mudstone 1 3.2 2.4 2.9 37 2.3 2610 
Sandy mudstone 2 3.6 2.6 2.6 39 2.2 2620 

Mudstone 1 2.5 1.3 2.1 34 1.6 2640 
coal 1.6 1.2 0.9 28 0.9 1638 

Mudstone 2 3.2 1.5 1.9 31 1.4 2634 
post office box stone 4.9 2.4 2.2 36 2.2 2662 

limestone 4.5 4.2 3.1 38 2.4 2860 
 

3.2.2. The influence range of advance abutment pressure 
of working face 

Based on the geological conditions of 24100 working face, 
FLAC 3D software is used to simulate the mine pressure 
behavior of working face in the process of coal seam mining. 
The distribution characteristics of advance abutment pressure 
in roadway are analyzed when the first weighting, periodic 
weighting and working face of 24100 working face are 
squared for one time. According to the actual record: the first 
weighting step of the working face is 28 ~ 30m (30m in the 

simulation calculation), and the periodic weighting step of the 
working face is 12 ~ 18m (15m in the simulation calculation). 
The inclined length of the working face is 300 m, and the 
working face is 300 m at a time. The change of advance 
abutment pressure of roadway is analyzed and recorded when 
the working face advances at different distances. The cloud 
diagram of vertical stress change at different distances of 
working face mining is shown in Figure. 4, and the change 
curve of advance abutment pressure at different distances of 
working face mining is shown in Figure. 5. 

 

 
(a) Working face mining 15m.    (b) Working face mining 30m. 

 
(c) Working face mining 300m. 

Figure 4. The vertical stress change cloud map of different distances in working face mining. 



 

208 

 
Figure 5. Working face mining advance abutment pressure curve at different distances. 

 
It can be seen from Fig.4 and Fig.5 that when the 300 m 

working face is squared once, the peak value of the advance 
abutment pressure is 48.06 MPa, the peak value of the 
concentrated stress is about 4.9 m away from the working face, 
and the stress concentration factor is 1.92. The advance 
abutment pressure increases first and then decreases with the 
increase of the distance from the head of the working face, 
and increases from the original rock stress to the peak value 
of the advance abutment pressure 4.1 ~ 4.9 m in front of the 
working face. When the distance of the advance working face 
is less than 10 m, the roadway is greatly affected by the 
advance abutment pressure, the surrounding rock is seriously 
broken, and the roof bearing capacity is poor. In the range of 
10 ~ 30m, the slope of the abutment pressure curve and the 
stress concentration factor are obviously reduced, and the 
surrounding rock of the roadway is in a relatively stable state 
at this stage. When the advance working face is 30 m, it 
gradually tends to be stable. The advance abutment pressure 
changes little in the range of 30 ~ 60 m, and then decreases to 
60 m in front of the working face, which is similar to the 
change trend of the original rock stress. Considering the site 
construction conditions and the maximization of economic 
benefits, grouting reinforcement should be carried out within 
the range of 10 ~ 30 m ahead of the original support to 
improve the bearing capacity of the surrounding rock of the 
roof. 

3.3. Supporting parameters of grouting anchor 
cable 

(1) Grouting time 
The advance grouting anchor cable construction should be 

completed within 30 m of the advance working face, and the 
grouting reinforcement should be completed within 10-30 m 
of the advance working face. 

(2) Density of grouting anchor cable 
According to the previous analysis, the support strength (Pc) 

of the reinforced grouting anchor cable in the mining roadway 
of the advanced dynamic pressure zone of the 24100 working 
face is not less than 50.6 kN/m2. Firstly, the support 
parameters of the reinforced grouting anchor cable are 
determined by theoretical calculation. 

Combined with the actual situation of No.11 Coal Mine, 
the diameter of hollow grouting anchor cable is Φ22 mm, the 
anchoring force is 300 kN, and the breaking load is 420 kN. 
The number of grouting anchor cables at least constructed 

within 30 m ahead is: 
 

 𝑛               (6) 

 
In the formula: n is the number of grouting anchor cables, 

root; Pc reinforcement support strength, 50.6kN/m2; s is the 
area of roadway roof ahead of 30 m, 160 m2; k1 is the effective 
coefficient, take 0.8; F is the anchoring force of grouting 
anchor cable, 300 kN. 

After calculation, n = 34, that is, in the range of 30 m ahead, 
at least 34 grouting anchor cables are used in the roof, and the 
support density is 0.21/m2. 

(3) Anchor cable row spacing 
In the range of 30 m ahead, at least 34 grouting anchor 

cables are constructed in the roof, and 2 grouting anchor 
cables are constructed in each row. There are at least 17 rows 
of anchor cables in the roof of the leading section, and the row 
spacing i is: 

 

𝑖 1.875              (7) 

 
Therefore, the row spacing of the anchor cable is not more 

than 1.875 m. 
(4) Length of grouting anchor cable 
In order to meet the requirements of support strength, it 

should meet: 
 
 𝐿 𝐿 𝐿 𝐿 𝐿              (8) 

 
In the formula: L is the total length of the anchor cable, m; 

La is the anchorage length in stable rock strata. 
 

  𝐿 𝐾 1.16            (9) 

 
In the formula: K1 safety factor, take 1.2; the diameter of d1 

is 0.022 m; the tensile strength of fa is 1760MPa; the bonding 
strength of fc anchor cable and anchoring agent, 10MPa; Lb 
needs the thickness of the suspended unstable rock layer, 
which is 5.6 m. The thickness of Lc plate and anchorage is 
0.15 m. The exposed tension length of Ld is 0.25 m. 

The theoretical length of grouting anchor cable is 
calculated to be L = 7.16 m. Therefore, the length of grouting 

-5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70
20

25

30

35

40

45

50

20

25

30

35

40

45

50

 Advancing 15m
 Advancing 30m
 Advancing 300m

A
d
v
a
n
c
e
 
a
b
u
t
m
e
n
t
 
p
r
e
s
s
u
r
e
 
(
 
M
P
a
 
)

Distance from working face ( m )

Original rock stress is 25 MPa



 

209 

anchor cable should not be less than 7.16 m. Combined with 
the actual situation on site and considering a certain safety 
factor, the length of grouting anchor cable is determined to be 
7.3 m. Strengthen the support of the mining roadway in the 
advanced dynamic pressure area of the 24100 air roadway. 
Combined with the existing roadway support, the 
specifications of the grouting anchor cable are Φ22 mm × 
7300 mm, and the support density is 0.21 roots/m2. 

(5) Injecting paste material 
Through field experiments, cement-based grouting 

materials were selected for anchorage support. P.O 42.5 
ordinary Portland cement and water were selected to prepare 
cement slurry according to water-cement ratio of 0.8, and 4 % 
ACZ-I additive was added to improve the rheological 

properties of slurry and enhance the stability of surrounding 
rock. 

4. Simulation Verification 

4.1. Grouting anchor cable reinforcement 
support scheme  

Based on the above analysis, the reinforcing anchor cable 
support design is carried out for the advance section of 24100 
return air roadway. The specification of grouting anchor cable 
is Φ22mm × 7300mm. The supporting section is shown in 
Figure 6. 

 

 
Figure 6. Pre-support section diagram of reinforcing grouting anchor cable in 24100 return air roadway. 

 

4.2. Feasibility analysis of advanced support 
scheme 

Continue to use the above chapter model, after the model 
is assigned to the balance, the return air roadway is excavated. 
After the excavation is completed, the bolt anchor cable and 

grouting anchor cable are set. The bolt and anchor cable 
support parameters continue to use the original support 
technology scheme, and the operation is balanced. The 
working face is excavated in a square (300m), and the 
deformation of the surrounding rock of the roadway is 
analyzed, as shown in Figure 7. 

 

 
(a) Grouting anchor cable row spacing diagram. (b) The 30 m plastic zone ahead of working face. 

 
(c) The 30 m vertical displacement ahead of working face. (d) The horizontal displacement. 

Figure 7. Deformation law of roadway surrounding rock. 



 

210 

 
Through numerical simulation, it is found that when the air 

roadway is 30 m ahead of the working face, after the advanced 
strengthening support, only the shallow surrounding rock 
damage occurs in the roadway floor, which is less affected by 
the mining of the working face; after strengthening support, 
the roof subsidence is 101.8 mm, which is 31.6 % lower than 
that of the original support. The roof subsidence is 76 mm, 
which is reduced by 37.5 % compared with the original 
support. The strengthening support of the leading section of 
the air roadway can maintain the stability of the surrounding 
rock of the roadway. 

5. Conclusions 
In view of the problem that the 24100 return air roadway is 

affected by the mining of the working face, the roof cracks of 
the inclined roadway develop, break and sink, and form more 
net pockets. Through a series of studies, the following 
conclusions are obtained: 

(1) Based on the suspension theory, the original support 
strength of the roadway roof is calculated to be 238.9 kN/m2, 
and the support strength required for the roof under the 
influence of dynamic pressure is 289.5 kN/m2. It is 
determined that the support strength required for the advanced 
section of the roof of the 24100 working face should not be 
less than 50.6 kN/m2. 

(2) The stress distribution and deformation law of 
surrounding rock of roadway in advance section are analyzed 
by FLAC 3D. The numerical simulation results show that the 
influence range of roadway by advance abutment pressure is 
about 60 m, the peak value of advance abutment pressure is 
48.06 MPa, and the stress concentration coefficient is 1.92. 

(3) The slope of the abutment pressure change curve and 
the stress concentration coefficient are obviously reduced in 
the range of 10 ~ 30m, and gradually tend to be stable when 
the working face is 30 m ahead. The abutment pressure 
changes little in the range of 30 ~ 60m. The support should be 
strengthened in the range of 30 m ahead of the working face, 
the deformation of the surrounding rock of the roadway 
should be controlled, and the grouting reinforcement should 

be carried out in the range of 10 ~ 30m ahead of the working 
face. 

(4) The hollow grouting anchor cable with a specification 
of Φ22mm × 7300mm and a row spacing of 1900mm × 
1500mm can achieve better reinforcement support effect and 
ensure safe and efficient mining of the working face. The 
FLAC 3D numerical simulation is used to verify the advanced 
reinforcement support scheme. After the grouting anchor 
cable is used to strengthen the support, the roof subsidence is 
reduced by 40.3 % compared with the original support, and 
the two-side convergence is reduced by 37.5 %. The anti-
deformation ability of the surrounding rock of the roadway 
roof after the grouting anchor cable reinforcement support is 
improved. 

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