Introduction:
HOBAS pipe trenchless installations include
sliplining rehabilitation, pipe bursting, direct jacking,
microtunneling and secondary tunnel lining (water-way carrier)
applications. HOBAS pipes provide many cost saving benefits to the
user and installer, regardless of the installation method;
however, several unique attributes are ideally and inherently
suited to trenchless installation methods. In fact, HOBAS pipes
have been so successful in these applications that they have
earned the label of "Premier Trenchless Pipe."
Installations
Definitions:
Sliplining Rehabilitation:
A process whereby a deteriorated pipeline is
lined (or relined) with a new pipe of a smaller diameter to
refurbish the original pipe for continued service.
Direct
Jacking:
A tunneling process whereby a single new pipe
is installed in one pass. A bore head begins the tunnel excavation
from an access shaft and is pushed along by hydraulic jacks that
remain in the shaft. The link to the boring head is maintained by
adding jacking pipe between the jacks and the head. By this
procedure, the pipe is laid as the tunnel is bored.
Microtunneling:
Microtunneling is defined as a trenchless construction method for
installing pipelines. The North American definition of
microtunneling describes a method and does not impose size
limitations on such method; therefore, a tunnel may be considered
a microtunnel if all of the following features apply to
construction:
- Remote Controlled: The microtunneling boring machine
(MTBM) is operated from a control panel, normally located on
the surface. The system simultaneously installs pipe as
spoil is excavated and removed. Personnel entry is not
required for routine operations.
- Guided: The guidance system usually references a
laser beam projected onto a target in the MTBM, capable of
installing gravity sewers or other types of pipelines to the
required tolerances, for line and grade.
- Pipe Jacked: The pipeline is constructed by
consecutively pushing pipes and the MTBM through the ground
using a jacking system for thrust.
- Continuously supported: Continuous pressure is
provided to the face of the excavation to balance groundwater
and earth pressures.
Tunnel Waterway Carrier:
The second lining (waterway carrier) in a two
pass tunnel construction method.
Pipe
Characteristics:
Description:
HOBAS pipes for trenchless installations are a
corrosion resistant, centrifugally cast, glass-fiber reinforced
polymer mortar, tubular product connected with push-together,
rubber ring-sealed joints. The pipes and joints may be pressure or
non-pressure rated depending on the required service.
Diameters/Dimensions:
The nominal diameter range is 12" to
102". Maximum section length is 20 ft. with standard shorts
in even divisions available.
Design:
In all installations, HOBAS pipes are designed
as semi-rigid, flexible conduits to withstand all loads without
structural aid from old pipes (sliplining) or primary tunnel
liners.
Benefits:
HOBAS fiberglass pipes provide many important,
cost saving benefits to the user and installer. Some benefits are
universal (apply regardless of installation method), while others
are specific to trenchless applications.
Benefits Specific to Trenchless
Installations:
- Due to the segmented pipes, the sewer may be lined while in
service (live), avoiding costly and risky by-pass pumping.
- Lower pushing or jacking insertion loads due to the smooth,
constant O.D. and lightweight straight pipe wall.
- Fewer access pits needed due to the long pushes possible
with high strength, smooth wall pipes.
- Small access pits required.
- Radius curves easily negotiated with the gasket-sealed
joints.
- Smaller primary tunnel (10 to 15%) and less excavation (20
to 30%) on two pass tunnels.
- Fast liner insertion due to push-together joints and
lightweight 20 ft. sections.
- Easy to grout liners' annular space due to high stiffness,
low creep design.
- High reliability and lower risk installations due to the
composite material resiliency and the consistent, high quality
generated by the computer controlled pipe manufacturing
process.
Conclusion:
HOBAS pipes' many unique attributes provide
installation and operation benefits unavailable with other
materials. Use of HOBAS pipes in trenchless installations results
in improved reliability, reduced risk, and lower costs. HOBAS
pipes have truly earned the title of "Premier Trenchless
Pipe." Copies of an article, "Success of Centrifugally
Cast Fiberglass Pipes in Trenchless Installations," that
covers the topic in greater detail are available upon request.
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