INSTALLATION OF SAND DRAINS

1,242,951. Boring earth. RAYMOND INTERNATIONAL Inc. 17 Jan., 1969 [6 Feb., 1968], No. 2886/69. Heading E1F. A sand drain is formed by drilling a hole in the ground, introducing fluid into the hole, causing the fluid to move upwardly in the hole to wash spoil out from the top of the hole, and filling the hole with drain solids. In the embodiment shown the hole is drilled using a bit 16 on a hollow pipe 14 driven by motor 18. During drilling the spoil is flushed out by water pumped down pipe 14 through valve 30 in housing 22. After drilling valve 30 is moved to shut water supply from inlet 28 and to open sand inlet 26. The sand falls down pipe 14 aided by a water jet from nozzle 38 and fills the hole as the pipe is removed. In a second embodiment (Figures 6-13 not shown) there is a jet forming nozzle member positioned at the bottom of a non- rotary pipe and connected to a bi-conical valve member in housing 22. When the valve member closes the sand inlet and fully opens the water inlet, the nozzle member is in a position with respect to the pipe to form jets, while when the valve member opens the sand inlet and partially closes the water inlet the nozzle member is moved into a position to allow sand to fall out of the pipe. In a third embodiment the hole is drilled using a rotating jetting pipe having a paddle to keep the spoil in suspension. The paddle may have teeth on its outer edges to scratch the sides of the hole. After the hole has been drilled the pipe is quickly removed and a sand drain tube having a closed bottom inserted into the hole to cause the spoil in suspension to rise up the annulus .between the tube and the walls of the hole. The tube is then filled with sand and pressurized air fed to the tube to cause the bottom of the tube to be blown off. The bottom is composed of a wooden plate nailed to the tube. The tube is raised allowing sand to fill the hole.