Pipejacking is a method to install pipelines under the ground. Heavy duty hydraulic cylinders are used for pushing special pipes into the ground together with tunnel boring machine (TBM) attached to the first pipe..

Nguồn: indstt.com   

     There are no limits to the length of jacked pipeline, however practical engineering and economic issues raise some disadvantages.

     Pipelines can be jacked in straight line or in curved line with different radiuses.

     With pipejacking method, soil can be supported and soil displacement possibility is reduced.

Source: mymetroworld.org

  • Construction of sewers by pipejacking method is implemeted in accordance with the following steps:

1.    Investigating of conditions of soil before construction and surveying and locating of site.
2.    Construction of launching shaft and receiving shaft.
Currently in Vietnam, launching shaft and receiving shaft for construction of sewers can be implemented in 02 ways 
-    Sinking of caissons
-    Driving of Larsen sheet piles
Launching shaft and receiving shaft are calculated and designed based on results of prior geology investigation.
3.    Accurately positioning of softeyes at entry point of launching shaft and at exit point of receiving shaft.
Positioning of softeyes is based on design invert of pipe.
4.    Transporting of construction equipment, jacking pipes to site.
Structure of Jacking pipes are different from that of pipes for opencut method to suit pipejacking work. 03 types of jacking pipes:
-    Standard pipe: pipe with lifting anchors for being handled and lowered in jacking position.
-    Bentonite pipe (Grouting pipe): similar to standard pipe except for 03 holes evenly located on pipe wall circumferentially (120o interval) for injection of Bentonite as lubricant around the outer surface of pipe .

-    Intermediate pipe: this is a set of pipes consisting of male pipe and female pipe. Interjack stations are installed between these sets of pipes. When pipeline completely installed, interjack stations are removed and the gaps left are closed by some pushing.
5.    Setting up of supporting equipment on the ground: mobile crane, settling tank, suction truck, generator, Bentonite pumping station

Bentonite pumping station will pumps Bentonite suspension onto pipe outer surface to reduce friction between soil and pipe outer surface.

6.    Setting up of supporting equipment in shaft: Slurry pump system, ventilation system, control system, hydraulic system, electrical system, Bentonite system, laser guiding system, launching seal, thrust wall.
7.    Installation of jacking frame, connection of jacking frame with supporting equipment: Hydraulic cylinders, push ring, spacer, TBM, intejack stations (if required)
8.    Operation of jacking system to push TBM into the ground as commencement of the pipejacking work. Connecting of pipes to TBM and interjack stations (if any) until the first pipe and TBM enter receiving shaft. 
During pipejacking progress, main jacking force is monitored. If the jacking force is too high, pipes can break. Then interjack stations should be installed to reduce main jacking force. 
Positions of interjacking stations are determined based on calculation.
9.    At receiving shaft, receving seal and receiving frame for TBM are installed.
10.  TBM and supporting equipment are removed from receiving shaft. Cleaning of construction site is done then as regulated.

Applications:

  • Pipejacking method is mostly applied in installation of pipelines for new drainage & sewerage, water mains, gases, oil, electric cables, telecommunication cables, or to replace old sewers.        
  • Special applications include jacking of pipes with round or rectangular cross section for pedestrians subway, road tunnel.
  • Applied for crossing of obtacles such as high ways, rail roads, rivers, channels, canals, buildings, airports, which are in the way of pipelines to be installed.

Advantages:

a.    Engineering:

  • Possible at high depths. Normally optimal depth for pipejacking method is equal to or greater than 6m. At lower depths, pipejacking method is considered in the relation of several factors such as finance, environment,…
  • Able to stop ground water ingress by seals. 
  • Low risk of subsidence.
  • Minimum disturbance on the ground.
  • Minimum excavation and reinstatement.
  • Little impact to other infrastructure works.

b.    Environment:

  • Environmental advantages are gained by applying pipejacking method against conventional open cut methods. Normally, the trenchless method reduces quantity of materials ‘”in” and “out” leading to reduction of work of soil disposal and surface reinstatement.
  • Comparision table of Environmental aspects between open cut method and pipejacking method.
  • In many cases, application of pipejacking method instead of open cut method brings about positive impact to safety at work, to lives of the people living around and closed to construction site, to local environment.

 

 


Support - Consultancy

Contact for drainage failures

(028)3 823 4444

Head Office

4 Nguyễn Thiện Thuật, phường 24, quận Bình Thạnh, TP.HCM

Tel: (028) 38.230.800 - (028) 730.555.33

Fax: 028.38.230.688

Email: thoatnuoc@udc.com.vn

Web links