Page 376 - Trenchless Technology Piping Installation and Inspection

326 Cha pte r Ei g h t

Monitor

LED target Pilot head
Theodolite

FIGURE 8.13 Line and grade control system. (Source: Bohrtec, 2008.)

FIGURE 8.14 Jacking frame. (Source: Bohrtec, 2008.)

3. Pilot tubes: The pilot tubes as shown in Fig. 8.15 are particu-
larly made of small sections so that they can be accommo-
dated in the shafts. The tubes shall rigidly connect to each
other, the steering tip, and the enlargement casing, and have
a clear inside diameter large enough to adequately view the
lighted target. The tubes shall withstand the torque encoun-
tered in the steering process.
4. Enlargement casing: The enlargement casing used must be
strong enough and must have a diameter slightly larger than
the product pipe. The casing may match the product pipe but
by use of the newest powered reaming heads and powered
cutterheads only one casing is used for many larger product
pipe size. It must connect properly with the pilot tubes.
5. Soil-transportation system: The soil is transported through the
auger-system train, which is inside the casing.