Page 35 - Trenchless Technology Piping Installation and Inspection

10 Cha pte r O n e

FIGURE 1.6 Conventional pipe jacking operation.

the operator works behind the tunneling face, so the applicable
dimaters are for work-entry pipes (usually more than 42 in.). Pipe
jacking is also a concept used in several trenchless technology meth-
ods, including microtunneling, horizontal auger boring, and pilot
tube microtunneling (see Chap. 8).
Where prefabricated pipe sections are jacked behind the cutter-
head. Figure 1.6 illustrates a mechanical cutting method. In this the
conventional pipe jacking method, new pipe sections are jacked from
a drive or entry shaft or pit (also called jacking shaft or pit) toward
exit or receiving shaft or pit so that the complete string of pipe is
installed simultaneously with the excavation of the tunnel. Since the
pipe sections are jacked in this method, the pipes are designed and
manufactured to take both jacking and permanent loads (soil, hydro-
static, and traffic). However, usually jacking loads (while different
from permanent loads) control the pipe design. The main compo-
nents of a conventional pipe jacking operation include
• Entry and exit shafts
• Tunnel-boring machine (TBM), earth-pressure balance machine
(EPBM), open shield excavator, and so on, as described in
later sections.
• Spoil removal system (such as a conveyer belt and haul units/
moving carts over tracks)
• Jacking frame
• Hydraulic jacks