Method and apparatus for compacting backfill in trenches

Abstract

This invention relates to a backfill compaction apparatus of a type particularly well suited to the puddling and compaction of loose soil around pipes laid in trenches, such apparatus being characterized by a self-propelled carriage adapted to straddle the pipe and advance therealong incrementally, a mast supported in upstanding relation on the front end of the carriage, a forwardly-extending boom mounted on the mast for vertical movement relative thereto, means operatively interconnecting the mast and boom for raising and lowering the latter, a tool-carrying platform suspended from the boom in overhanging relation to the trench to be backfilled, at least one pair of transversely-spaced combination puddling and vibrating subassemblies hanging from the tool-carrying platform adapted to enter the trench on opposite sides of a pipe laid therein, said subassemblies each including an elongate rigid nozzle for introducing water beneath the surface of the backfill and a vibrator connected to said nozzle for movement therewith, means for introducing water into said nozzles connectable to a remote pressurized source thereof, and a self-contained hydraulic system on board the carriage for powering the vibrators. The invention also encompasses the novel method of compacting backfill which comprises digging a hole into the backfill with a jet of water under pressure while simultaneously vibrating the surrounding loose soil until it caves into the puddle of water at the bottom of the hole thus produced.

Dependencies are inferred from the claim text.