12
NUMERICAL SIMULATION
CALCULATION VERIFICATION
Taking two supports (interaction between analysis frames)
at 45° inclination Angle as the research object, the dynamic
load numerical simulation of hydraulic support was carried
out by using FLAC 3D finite difference method under the
same load environment. A 1:1 three-dimensional numerical
calculation model of ZZ6500/22/48 four-column hydrau-
lic support was established by Rhino, and the support was
inclined to be arranged along the working face. As shown
in Figure 21. When modeling, the top beam, shield beam,
front connecting rod and back connecting rod are treated
as elastomer, and the base is regarded as rigid body. The
grid is divided by Rhino, and then imported into FLAC3D
through Kubrix. The model contains 166,128 units and
614,201 grids.
In the hydraulic support model with large dip Angle
and high mining height, the top beam, tail beam and cover
beam of the support are all 16Mn steel with an elastic
modulus of 208Gpa, Poisson ratio of 0.31, and density of
7850kg/m3 the elastic modulus of the column is 980 MPa,
Poisson ratio of 0.3, and density of 7850kg/m3. The power
medium of the hydraulic cylinder is emulsion, and the bulk
elastic modulus is 0.5GPa.
The positive impact load shown in formula (6) is
applied to the top beams of the two supports at the same
time to simulate the positive pressure impact. Under the
positive pressure impact, the support is subjected to the
strongest dynamic load, and the support is prone to insta-
bility such as compression and tipping under this type of
impact. The numerical simulation results of the load on
the top beam of the support group are shown in Figure 22
(a). At 20 ms, when the excitation load reaches the maxi-
mum value, it can be seen that the stress is concentrated at
the side of the top beam, and the maximum stress reaches
1500 MPa. The interaction between the support frames
is obvious, and even the phenomenon of biting the frame
may occur. Need to do key protection. The stress of most
parts of the top beam is about 250 MPa, and the stress
concentration of the two supports mainly occurs at the 2/3
position of the top beam (that is, between the front and
rear columns) during 40-60 ms, and extends to the side
of the top beam. At 100 ms, the load on the top beam of
the support tends to balance, the dynamic load is released,
and the stress distribution of the two supports is basically
symmetrical. According to the stress distribution character-
istics of different time periods, it is inferred that when the
top beam is impacted, the impact will be transmitted from
the four columns to the base, and absorbed by the bottom
plate, and the “support surrounding rock” system reaches a
new balance.
For the push-back effect of the shield beam (according
to Formula 6), P0=383 kN (that is, the impact effect on the
support after direct push-off within the range of a single
support is taken as 27000N/m3×2.32 m×1.75 m×3.5 m),
and the load increase amplitude Pr is taken as 60 kN to
simulate the push-back impact. As shown in Figure 22 (b),
tensile stress concentration occurs at 1/3 of the shield beam,
reaching a maximum of 7 MPa, and extends from this posi-
tion to both sides, showing a decreasing trend, indicating
that when the shield beam is impacted, the load spreads
around along the impact center, but when it is transmitted
to the angular part, the dynamic load cannot be transmit-
ted quickly and effectively, resulting in local stress con-
centration. The stress at the upper end of the shield beam
of the two supports is greater than that at the lower end,
and the stress on the lower support is greater than that on
the upper support. This is because when the two supports
are impacted at the same time, the upper support will be
deflected and unstable, and the load will be transferred to
the lower support, thus affecting the stability of the lower
support. At 100 ms, except for the stress concentration at
the hinged joint with the top beam, the stress of the rest
parts of the shield beam is basically 0. Based on the stress
distribution at different times, it can be inferred that when
the shield beam is impacted, the dynamic load will spread
around along the impact position, transfer to the top beam
or base, and then transfer to the base and surrounding rock
by the column.
For the side push load between the frames, P0=615 kN
and the load increase amplitude Pr were taken to 100 kN to
simulate the back push impact. As shown in Figure 22(c), Figure 21. Numerical model diagram of support (group) for
high inclination face
NUMERICAL SIMULATION
CALCULATION VERIFICATION
Taking two supports (interaction between analysis frames)
at 45° inclination Angle as the research object, the dynamic
load numerical simulation of hydraulic support was carried
out by using FLAC 3D finite difference method under the
same load environment. A 1:1 three-dimensional numerical
calculation model of ZZ6500/22/48 four-column hydrau-
lic support was established by Rhino, and the support was
inclined to be arranged along the working face. As shown
in Figure 21. When modeling, the top beam, shield beam,
front connecting rod and back connecting rod are treated
as elastomer, and the base is regarded as rigid body. The
grid is divided by Rhino, and then imported into FLAC3D
through Kubrix. The model contains 166,128 units and
614,201 grids.
In the hydraulic support model with large dip Angle
and high mining height, the top beam, tail beam and cover
beam of the support are all 16Mn steel with an elastic
modulus of 208Gpa, Poisson ratio of 0.31, and density of
7850kg/m3 the elastic modulus of the column is 980 MPa,
Poisson ratio of 0.3, and density of 7850kg/m3. The power
medium of the hydraulic cylinder is emulsion, and the bulk
elastic modulus is 0.5GPa.
The positive impact load shown in formula (6) is
applied to the top beams of the two supports at the same
time to simulate the positive pressure impact. Under the
positive pressure impact, the support is subjected to the
strongest dynamic load, and the support is prone to insta-
bility such as compression and tipping under this type of
impact. The numerical simulation results of the load on
the top beam of the support group are shown in Figure 22
(a). At 20 ms, when the excitation load reaches the maxi-
mum value, it can be seen that the stress is concentrated at
the side of the top beam, and the maximum stress reaches
1500 MPa. The interaction between the support frames
is obvious, and even the phenomenon of biting the frame
may occur. Need to do key protection. The stress of most
parts of the top beam is about 250 MPa, and the stress
concentration of the two supports mainly occurs at the 2/3
position of the top beam (that is, between the front and
rear columns) during 40-60 ms, and extends to the side
of the top beam. At 100 ms, the load on the top beam of
the support tends to balance, the dynamic load is released,
and the stress distribution of the two supports is basically
symmetrical. According to the stress distribution character-
istics of different time periods, it is inferred that when the
top beam is impacted, the impact will be transmitted from
the four columns to the base, and absorbed by the bottom
plate, and the “support surrounding rock” system reaches a
new balance.
For the push-back effect of the shield beam (according
to Formula 6), P0=383 kN (that is, the impact effect on the
support after direct push-off within the range of a single
support is taken as 27000N/m3×2.32 m×1.75 m×3.5 m),
and the load increase amplitude Pr is taken as 60 kN to
simulate the push-back impact. As shown in Figure 22 (b),
tensile stress concentration occurs at 1/3 of the shield beam,
reaching a maximum of 7 MPa, and extends from this posi-
tion to both sides, showing a decreasing trend, indicating
that when the shield beam is impacted, the load spreads
around along the impact center, but when it is transmitted
to the angular part, the dynamic load cannot be transmit-
ted quickly and effectively, resulting in local stress con-
centration. The stress at the upper end of the shield beam
of the two supports is greater than that at the lower end,
and the stress on the lower support is greater than that on
the upper support. This is because when the two supports
are impacted at the same time, the upper support will be
deflected and unstable, and the load will be transferred to
the lower support, thus affecting the stability of the lower
support. At 100 ms, except for the stress concentration at
the hinged joint with the top beam, the stress of the rest
parts of the shield beam is basically 0. Based on the stress
distribution at different times, it can be inferred that when
the shield beam is impacted, the dynamic load will spread
around along the impact position, transfer to the top beam
or base, and then transfer to the base and surrounding rock
by the column.
For the side push load between the frames, P0=615 kN
and the load increase amplitude Pr were taken to 100 kN to
simulate the back push impact. As shown in Figure 22(c), Figure 21. Numerical model diagram of support (group) for
high inclination face