GB713256A - Improvements relating to apparatus and methods for constructing underground concretepipes or land drains in situ - Google Patents

Abstract

713,256. Land drains. NATIONAL RESEARCH DEVELOPMENT CORPORATION. April 9, 1952 [April 9, 1951], No. 8193/51. Classes 6 (1) and 33. [Also in Group X] To form land drains in situ, there is mounted on a mobile frame 11, to be moved vertically and about a transverse axis by jacks 36 and 50, an apparatus comprising a mole plough, an extruder carried or towed at the rear of the plough, and means for forcing concrete under pressure through the extruder and around the vibrated core thereof to form an extruded concrete pipe lining the tunnel made by the plough. Concrete is raised by a screw conveyer from a hopper 62 into a hopper 13 from which it is gravity-fed down through the hollow coulter 12 supporting the plough to a helical screw positioned behind the plough. The concrete is urged rearwards by the screw 17 and is extruded through the annular space 23 between the enlarged end 22 of the tubular body 15 of the plough and a longitudinal vibrating core 21 to form a continuous pipe. To prevent clogging of the concrete as it passes down the coulter, a vibrator unit is connected to the walls of the coulter or to an elongated plate extending down the inside thereof. The core is hollow and contains a mechanically, electrically or fluid-operated vibrator. Continuous or discontinous openings in the concrete lining are formed by various forms of perforating tool mounted on or in the core 21, and a helix of reinforcing steel wire can be incorporated in the lining, the wire emerging from an aperture in the core 21. The wire is automatically paid out at a rate depending upon the rate of advancement of the machine by feed means within the core which may tow a second core behind it. The depth of the mole can be altered to meet any variation of ground contour by a control cam mounted on a wheel of the vehicle frame. When one drain crosses the bore of another drain its bore is reduced by a temporary increase in the rate of extrusion of the concrete with which may be combined a wetting agent, a cement dispersing agent, a gas-forming material or compressed air.