Page 375 - Trenchless Technology Piping Installation and Inspection

Inspection and QA/QC for Trenchless Installation and Replacement Methods 325

Verify the back-thrust block is structurally adequate, jacking force is within the range
of calculated jacking force, and that the jacking force is recalculated whenever the
operation is stopped.

Verify sufficient lubrication fluid quantity is used, and a lubrication system properly
injects lubricant on the inside and outside of the pipe, and the volume or pressure of
slurry flow in the supply and return side of the slurry loop is equal and steady.
Verify any unsuccessful tunnel is back-filled immediately.
Verify each end of the pipe is enclosed, restoration is completed, and attach
Inspector’s Daily Report (IDR), form 2228.
Permit No. ___________________________
Inspector: ___________________________
Date: _______________________________

FIGURE 8.12 Sample checklist for inspection of microtunneling operations.
(Continued)

pipe is fixed the next step is the selection of jacking frame.
The jacking frames are chosen on the basis of specifications
and actual site conditions and design requirements.

8.3.3 Construction Considerations
Every effort must be made to estimate soil conditions as accurately as
possible. To design a PTMT project, step-wise planning is necessary.
Following are the different aspects that must be considered while
planning and designing a PTMT project.
Equipment

1. Line and grade control system: The line and grade control sys-
tem includes, but not limited to, a theodolite, lighted target,
camera, and monitor screen as shown in Fig. 8.13.
2. Jacking frame: The jacking frame must generate enough force
to push the pipe from the drive shaft to receiving shaft. The
design must be such that force is transferred to the pipes uni-
formly. It is very important to select a correct jacking frame
for a given set of conditions. There are various factors to be
considered while selecting a jacking frame, like pipe diame-
ter, subsurface conditions, jacking force required, size of shaft,
and the like. If a wrong jacking frame is selected, the project
may prove to be very costly to the contractor. Therefore, a
thorough investigation of the jacking frame specifications
and project conditions is very essential. Figure 8.14 presents
the jacking frame for the pilot-tube microtunneling.