GB962850A - - Google Patents

Abstract

962,850. Ramming soil. JERSEY PRODUCTION RESEARCH CO. Aug. 8, 1962 [Aug. 10, 1961; May 10, 1962], No. 30344/62. Heading E1G. [Also in Division H4] A device for generating seismic impulses in the ground comprises a cylinder housing a piston so connected to an impact member as to allow limited universal movement thereof the impact member striking the ground to produce the impulses. Two main embodiments are described; in the first (Fig. 1) a fuel ignition system generates the force to operate the piston, while in the second (Fig. 2 not shown) a large pressure differential is provided between the top and bottom of the piston to operate it. Fig. 1. The spherical end 54 of piston shaft 42 fits into a recess in a pivot plate 58 secured to the impact member 52, bolts 66, springs 68 and collar 64 also serving to secure member 52 to shaft 42 while allowing a limited amount of universal movement between them. Piston 34 is housed in the lower port of housing 10 while a free reaction mass 38 is housed in the upper, the two parts being separated by a combustion chamber 87. Operation. The "set" position is as shown, piston 34 being maintained in position by low pressure gas from source 78. Combustion chamber exhaust valve 102 is closed. The combustible mixture is fed from carburetter 106 to chamber 96, the low pressure air supply 78 is cut off and the mixture ignited. Piston 34 is driven downwards the gas escaping through port 74, and the reaction thrust forces mass 38 upwards, the air in chamber 85 escaping through port 84. The movement of piston 34 is damped towards the end of its travel since ports 74, 84 are not quite at the ends of their respective chambers. The reaction mass 38 is returned to its position against stops 30 by opening valve 102 to reduce the differential pressure and mass 38 will move downwards at a rate depending on the size of an orifice 91, since mass 38 will have moved past orifice 84. Alternatively (Fig. 2 not shown) rods secured to the reaction mass may move in dash-ports. In the embodiment of Fig. 4, the combustion chamber and reaction mass are omitted. The shaft 246 of piston 244 is secured to impact member 268 as before. The device is shown in the "set" position when only the small area of piston 244 bounded by seal 226 is in contact with the high pressure chamber 218. Exhaust valves 252A to 252n in the low pressure chamber below the piston are now opened and the high pressure gas forces piston 244 downwards. As soon as the seal between the top of the piston and 226 is broken, the gas acts on the whole top area of the piston which is driven rapidly downwards. The device may be anchored against upward movement or extra weight may be added. Movement of the piston 244 is damped when it has moved below ports 250. Manual and automation control systems are described (Fig. 6, not shown).