10
shown in Figure 16(c). High-definition monitoring showed
that the roof slipped to the support area below the tilt, the
twin system showed that the support fell 4.2° to the tilt
direction, and the average load of the sensor increased to
1.64 kN (0.84 MPa) after the initial support was restored.
At this time, the support base is slightly deflected, and there
is a greater possibility of tipping instability.
At 65° inclination Angle, when no load is applied to
the hydraulic support, the average load of the sensor on
the top beam of the support is 1.21 kN (0.62 MPa), and
the total load is 10.89 kN (5.56 MPa). During the load-
ing process, the average load of the support sensor gradu-
ally increased to 4.3 kN (2.19 MPa), the total load reached
38.7 kN (19.74 MPa), and then the total load of the top
beam dropped to 36.4 kN (18.57 MPa). The twin system
showed that the height of the hydraulic support column
yielded 13.6 cm, and the pressure continued. When the
total load reached 38.7 kN (19.74 MPa), the roof broke,
as shown in Figure 16(d). High-definition monitoring
showed that the roof slipped to the support area under the
tilt, and the twin system showed that the support fell 7.1°
to the tilt direction, and the support did not recover the
initial support.
During the twin system extraction experiment, the
inclination of the hydraulic support along the inclined
direction is shown in Figure 17, where the horizontal axis
represents the time to start loading and the vertical axis rep-
resents the inclination magnitude. Under the conditions of
35° and 45° working face inclination Angle, the support
becomes unstable after the roof is broken, because the sup-
port adopts the constant pressure support mode, and then
the support has lifting operation, and the support returns
to the original inclination Angle. Under the condition of
55° and 65° working Angle, after the instability of the sup-
port, the lifting operation can not restore the support to
the original working state. It can be found in the figure that
with the increase of working face inclination, the time of
support instability appears earlier and earlier. The support
from the beginning of instability (Angle begins to decrease)
to the automatic adjustment of the balance (Angle begins
to increase) time is increasingly longer, at 35° about 0.5s,
at 65° about 0.8s. The Angle variation of the bracket also
increases with the increase of the Angle. When the Angle
varies from 35° to 65°, the Angle variation is 3.4°, 4.2°, 4.2°
and 7.1°, respectively. With the increase of the Angle, it is
more and more difficult for the bracket to recover to the
original Angle after instability.
Under the four inclined angles, the broken state of the
roof is different. As shown in Figure 18 (a), under the con-
dition of 35°, the roof breaks under load, impacting the
shield beam and then sliding to the goaf, resulting in a large
broken rock mass of the roof. As shown in Figure 18 (b),
under the condition of 45° inclination Angle, the fracture
degree of the roof strata is greater than that of 35°, but
there are still large rock strata at this time. As shown in
Figure 18(c), when the inclination is 55°, the roof strata are
seriously broken, and large rock strata are relatively rare. As
shown in Figure 18 (d), when the inclination reaches 65°, it
is difficult to see large broken rock layers and the roof is seri-
ously broken. It shows that with the increase of inclination
Angle, the degree of fracture of roof strata increases, and the
Figure 17. Changes of bracket Angle under different
inclination angles
Figure 18. Broken state of roof under different
shown in Figure 16(c). High-definition monitoring showed
that the roof slipped to the support area below the tilt, the
twin system showed that the support fell 4.2° to the tilt
direction, and the average load of the sensor increased to
1.64 kN (0.84 MPa) after the initial support was restored.
At this time, the support base is slightly deflected, and there
is a greater possibility of tipping instability.
At 65° inclination Angle, when no load is applied to
the hydraulic support, the average load of the sensor on
the top beam of the support is 1.21 kN (0.62 MPa), and
the total load is 10.89 kN (5.56 MPa). During the load-
ing process, the average load of the support sensor gradu-
ally increased to 4.3 kN (2.19 MPa), the total load reached
38.7 kN (19.74 MPa), and then the total load of the top
beam dropped to 36.4 kN (18.57 MPa). The twin system
showed that the height of the hydraulic support column
yielded 13.6 cm, and the pressure continued. When the
total load reached 38.7 kN (19.74 MPa), the roof broke,
as shown in Figure 16(d). High-definition monitoring
showed that the roof slipped to the support area under the
tilt, and the twin system showed that the support fell 7.1°
to the tilt direction, and the support did not recover the
initial support.
During the twin system extraction experiment, the
inclination of the hydraulic support along the inclined
direction is shown in Figure 17, where the horizontal axis
represents the time to start loading and the vertical axis rep-
resents the inclination magnitude. Under the conditions of
35° and 45° working face inclination Angle, the support
becomes unstable after the roof is broken, because the sup-
port adopts the constant pressure support mode, and then
the support has lifting operation, and the support returns
to the original inclination Angle. Under the condition of
55° and 65° working Angle, after the instability of the sup-
port, the lifting operation can not restore the support to
the original working state. It can be found in the figure that
with the increase of working face inclination, the time of
support instability appears earlier and earlier. The support
from the beginning of instability (Angle begins to decrease)
to the automatic adjustment of the balance (Angle begins
to increase) time is increasingly longer, at 35° about 0.5s,
at 65° about 0.8s. The Angle variation of the bracket also
increases with the increase of the Angle. When the Angle
varies from 35° to 65°, the Angle variation is 3.4°, 4.2°, 4.2°
and 7.1°, respectively. With the increase of the Angle, it is
more and more difficult for the bracket to recover to the
original Angle after instability.
Under the four inclined angles, the broken state of the
roof is different. As shown in Figure 18 (a), under the con-
dition of 35°, the roof breaks under load, impacting the
shield beam and then sliding to the goaf, resulting in a large
broken rock mass of the roof. As shown in Figure 18 (b),
under the condition of 45° inclination Angle, the fracture
degree of the roof strata is greater than that of 35°, but
there are still large rock strata at this time. As shown in
Figure 18(c), when the inclination is 55°, the roof strata are
seriously broken, and large rock strata are relatively rare. As
shown in Figure 18 (d), when the inclination reaches 65°, it
is difficult to see large broken rock layers and the roof is seri-
ously broken. It shows that with the increase of inclination
Angle, the degree of fracture of roof strata increases, and the
Figure 17. Changes of bracket Angle under different
inclination angles
Figure 18. Broken state of roof under different