About Pipe Umbrella in Tunnel, You Need to Know These
In recent years, in the construction of tunnel engineering and mining engineering in my country, the pipe umbrella system has been widely used, and it has become one of the most effective advanced support methods when passing through loose and broken strata in underground engineering construction. The application of this technology not only simplifies the tunnel construction process, and accelerates the construction speed, but also greatly improves the construction safety and economic benefits.
However, in the current tunnel construction, it is also found that there
are still unreasonable and inappropriate applications in the pipe umbrella
support, which not only affects the supporting effect, but also often buries
quality and safety hazards to tunnel construction, and even causes accidents.
Although scholars have carried out many studies on the theoretical basis,
numerical simulation, design calculation, etc. of the pipe umbrella system
technology, and there have been many successful application examples, it has
played a positive role in promoting the wide and effective application of the pipe
umbrella system technology. , but it should also be noted that it is still
urgent and meaningful to improve the advanced support technology of the tube
shed to make its performance more effective.
There are various methods of advanced support. The pipe umbrella system
has been widely used in tunnel engineering due to its simplicity of
construction and timeliness of support effect.
Stress Variation of Pipe Shed in Advance Support
When the tunnel passes through the loose and broken rock layers, the goal
of implementing the advanced support of the pipe shed is to limit the large
deformation and displacement of the surrounding rock of the tunnel due to the
tunnel excavation, to maintain the original state of the surrounding rock as
much as possible, to maintain the stability of the tunnel, and to ensure
construction safety. , to create good conditions for the excavation
construction; at the same time to avoid excessive subsidence of the tunnel roof
in the later stage, to ensure the long-term stability of the tunnel. Therefore,
in the design and construction of the advanced support of the pipe shed, special
attention should be paid to the force of the pipe shed at each construction
stage to ensure that the pipe shed is stable at each stage without obvious
deformation and displacement.
Pipe Shed Spacing
The advanced support of pipe sheds is mostly used in loose and broken
rock formations. If the spacing is too large, it will not only easily cause
large rocks to fall, but also the load on the shed pipes is too large, which is
not conducive to the stability and safety of the pipe umbrella system. At the same
time, large-diameter shed pipes will be used to improve the bearing capacity of
the system, which will increase the difficulty of construction; however, if the
spacing is too small, it will inevitably increase the workload of pipe shed
installation and affect the construction progress. The spacing between the tube
sheds can generally be selected between 400 and 800 mm; when the rock is broken
and easy to flow, the smaller value is selected.
Inclination
In the pipe shed advanced support system, the shed pipe mainly bears the
bending load; therefore, the pipe shed should be laid horizontally. However,
due to construction reasons, the horizontal tube shed cannot ensure that the
tunneling section remains unchanged when the tunnel is advanced. Therefore, in
actual construction, the tube shed is inclined outward at a certain angle.
It should be pointed out that the bottoms of all pipe sheds should be
placed on the curve parallel to the tunnel excavation contour line, so as to
ensure that each shed pipe in the pipe shed is uniformly loaded at each stage
and to avoid large local displacements.
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