GB1444014A - Soil sampling method and apparatus - Google Patents

Abstract

1444014 Earth drilling and sampling G PERCY TRENTHAM Ltd 29 March 1974 [23 May 1973] 24616/73 Heading E1F In a soil sampling technique, a hammer mechanism imparts blows to a lower anvil to drive a sample tube into the ground until contact of a pressure plate with the soil raises the mechanism clear of the anvil, the mechanism then being raised to contact an upper anvil and loosen the tube for withdrawal. The mobile drilling and core sampling rig disclosed includes a mast movable by rams from a horizontal transport position to an upright operative position in which an auger carried by a telescopic kelly extending through a rotary table can be used to drill a hole, the kelly extending automatically during drilling and each of the ten concentric sections of the kelly having thrust-transmitting teeth engageable with the teeth on the adjacent outer section upon extension. After the hole has been drilled to a required depth, the kelly is retracted and moved laterally by a ram so that a sampler 50 (Fig. 2) is aligned with the hole, the sampler then being run into the hole using a cable engaging a frame composed of crossbars 60 and rods 58 carrying a rotary hydraulic motor 74 with hammers 86 which, as the tension in the cable is relaxed and the frame 58, 60 is depressed by springs 84, engage a bar 88 on a lower anvil 56 carried by a cylinder 54, the lower anvil carrying a connector 64 secured by a clamp 68 to a stainless steel tube 70 in which is located a sample tube 72, the hammers serving to drive the tubes into the bottom of the borehole until the sample contacts a plate 62 and lifts the motor so that hammers no longer engage bar 88. As the cable is tensioned to retrieve the sampler, the motor is raised so that its hammers engage an upper anvil 56 on cylinder 54 to facilitate, withdrawal of the tubes, the springs 84 ensuring that the motor is depressed to disengage its hammers from the upper anvil once the tubes are withdrawn from the sample hole. Following its retrieval, the sampler is positioned with the lower end of tube 70 in a location collar (94) on the rig, and the clamp 68 is then released and the assembly including the cylinder 54, frame 58, 60 and motor 74 is removed from the tubes to allow the outer tube 70 to be clamped to the chassis of the rig while a sample extraction ram is passed up through the location collar to remove the sample and the tube 72 from the tube 70. The rig also includes a linkage supporting a casing clamp 98 (Fig. 4) and including rams for forcing casing sections into the ground before the soil is removed by the auger, the clamp comprising arms 100 which are pivotally interconnected at 102 and which are controlled by rams 104 via toggle linkages 106, the rams 104 being controlled by pilot valves which can be moved alternately to operative positions to cause angular oscillation of the casing held between the arms, the rams being free to float when the pilot valves are in their neutral positions An expandable clamp is engageable in successive casing sections to allow application of an upward force thereto when the casing is to be retrieved. Beneath the rotary table the rig includes a kelly pull-down unit unit incorporating wedges 110 secured via bearings 118 to plates 114, 116 which are movable towards each other by short-stroke rams 112 to cause the wedges to grip the kelly, the upper plate being carried by longer-stroke rams 120 used to apply the pull-down force.