Patent GB-1176595-A (GB)
Title: Method and means for determining soil resistance of subsurface layers.
Inventor: GEETER PETER JAN DE
IPC: E02D1/02
Filed: 1968-09-16
Abstract: 1,176,595. Testing soil in situ. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. Sept.16, 1968, No.43862/68. Heading G1S. A sounding pin 1 penetrates a soil layer under the weight of its suspended housing body 2, 6, and the force of penetration is transmitted through a spring 14. The pin is provided with a valve 4 which may contact a seat 9 in a part 10, the part defining a central hydraulic nozzle 13 and a circular row of nozzles 12 fed from a cavity 11 and a conduit 15. An electrical cable 19 is earthed to the body 2 and a cable 20, 23 is connected to a strain gauge 24. Cable 25 is also connected to earth and therefore to the cable 19. In operation, water under pressure is passed through the cavity and 11 along the distance pieces 8 to the nozzles 12 in the direction of arrows 28, thereby washing away the soil below the lowering body 2 and providing a bore hole for the body to allow the pin 1 to penetrate. The compression of the pin is measured by the strain gauge 24 and recorded and amplified via the electric cables. When the soil resistance is such that the weight of the body can drive the pin no further, say at 105 kg/cm<SP>2</SP>, then the valve 4 is opened by relative upward movement of the pin, and a jet of water passes through the nozzle 13 - see arrows 29- which jet washes away the soil beneath the pin. During the passage of the pin through a soil layer having a bearing capacity or resistance of over 105 kg/cm<SP>2</SP> no exact indication of this resistance can be measured. In Figs. 2 and 3 a frame 40 supports gimbal rings 43, 46 providing bearings for a free running guide wheel 41 connected to a rev counter 56 and a motor-driven guide wheel 42. Normally the conduit 17 passes over the wheels as long as the body 2 can descend. However, when the body 2 does not move down e.g. when the jet 29 is operating to break through a high resistance layer, then the conduit will slip with respect to the wheels. A second set of nozzles may be provided to erode the soil to a level just below the pin 1, their operation being automatically started when say an electric signal is received from the recorder or relative displacement between the pin 1 and the body 2 takes place. In Figs. 4-6 (not shown) the nozzles are controlled by valves (67, 68, 70, 72) biased by hydraulic pressure instead of by a spring 14, the flow being controlled by the valves which are switched by the position of the pin from the outer to the inner nozzles. In Figs. 7-12 (not shown) the jets may be angled to the body and the pin 1 provided with a pin and slot connection with its body. If the pin reaches a hard layer, as in Fig. 8 (not shown), then the jets wash away the softer layer just below the housing until the hard layer is reached, then the pin retracts into the housing and allows the jets to come close to the hard layer to wash it away to a level just below the pin, Fig. 10 (not shown). Thereafter the pin descends into the layer once again, Fig. 11 (not shown) and jet washing action continues normally to provide a passage for the body whilst the pin re-commences penetrating.