Clay Pipe Engineering Manual

Chapter 7, Microtunneling

A Technology for Clay Pipe

Microtunneling is the method of installing sewer pipe without the need of excavating trenches.

The system works this way: A launch shaft is excavated at the location of a future manhole. A thrust wall is installed to resist the jacking force. An articulated cutting head and shield is jacked into the ground at the proper horizontal and vertical alignment and pipe after pipe are jacked through from behind. The excavated soil is conveyed through the pipe by slurry or auger and removed at the launch shaft. An equipment operator maintains close control of the line and grade through the articulated action of the cutting head and laser guided steering system. The operation continues until the cutting head, shield and pipe emerge into a receiving shaft which is normally the location of a future manhole.

Clay pipe has the high compressive strength to resist the considerable jacking force and possesses the needed abrasion resistance to prevent external damage as the pipe is pushed through the surrounding ground. Additionally, clay pipe has the chemical resistance for longevity and tight joints to prevent leakage. Special low-profile joints have been designed to facilitate jacking. ASTM C 1208 and C 1208 M(metric) Vitrified Clay Pipe and Joints for Use in Jacking, Sliplining and Tunnels is the first standard specification explicitly developed for microtunneling pipe.

Municipalities, engineers and contrac-tors have the option to use microtunneling for the installation of sewers in congested and confined areas, deep trenches, unstable soils and in those places where conventional excavation would be economically prohibitive, socially disruptive or unsafe.

NCPI Engineering Manual

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