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Pipe Ramming |
Because the pipe is not fitted with a steering head, the line and grade are dictated by the initial set up of the pipe and the response of the pipe to native soil conditions. Deviations from line and grade may result from impacts with obstructions or crossing geologic contacts which preferentially “pull” the pipe in one direction by offering less resistance during hammering.
Pipe ramming consists of ramming a steel pipe through the soil using repeated percussive blows from a pneumatic hammer powered by an air compressor. The general process of construction begins with the alignment of the product pipe to the specified line and grade of installation. Once the pipe is properly braced and supported on line and grade, the pipe is fitted with a hammer adaptor, followed by pneumatic hammer.
Spoils enter the open end of the pipe throughout the ramming process, forming a soil plug which provides face support by counterbalancing soil overburden and groundwater pressures. Establishment of an adequate soil plug is therefore essential when unstable soils or groundwater are expected along the alignment. After the pipe is in place, spoils can be removed using an auger flight, compressed air, or water jetting.
