GB1492325A - Vane test probe primarily for underwater use - Google Patents

Abstract

1492325 Measuring shear strength of soils SOIL INSTRUMENTS Ltd and GOLDER HOEK & ASSOCIATES Ltd 9 July 1976 [14 July 1975] 29467/75 Heading G1S A probe for measuring the shear strength of soils, particularly that of underwater sediments, comprises a casing 1 with one end defining a cylinder 3 having an open end and housing a piston 4, a coupling 9 for connection to a test vane 30, Fig.2, a drive housed in the casing for applying a torque through the coupling to the vane and means to move the piston 4 away from the open end of the casing whereby the vane and case are drawn into the soil by the suction created. Piston 4 is connected to piston 5 within a cylinder 8, the cylinder 8 being connected to hydraulic lines 6, 7 connected to supply lines A, B. A non-return valve 20 is included in line 7, and a bleed valve 21 is connected to the lower part of cylinder 8. The drive comprises a piston 15 slidable but non rotatable in cylinder 16, hydraulic lines 17, 18 coupling the cylinder 16 to lines A, B, a rotatable but axially immovable shaft 10 connected to coupling 9, a member 12 rigidly connected to shaft 10 and having a helical channel 13, and rollers (not shown) at 14 carried by piston 15 and engaging channel 13. Shaft 10 carries a strain gauge 19 for measuring the torque applied. In use, with pistons 4, 5 in their lower positions and piston 15 in its upper position, the probe is lowered down a borehole and the vane 30 penetrates the soil on impact. Hydraulic pressure applied to line A causes piston 5 and hence piston 4 to move to their upper positions, the suction induced in cylinder 3 causing the vane and casing to penetrate further into the soils. Hydraulic pressure is then applied to line B to cause piston 15 to move downwardly to apply torque to the vane, movement of pistons 4, 5 being prevented by non-return valve 20. In the detailed construction shown in Fig.2, shaft 10 is hollow and carries wires 31 from strain gauge 19. The shaft 10 acts as the supply line A and includes ports 32, 33 for applying pressure to pistons 5 and 15. Supply line B applies pressure to piston 15 via coupling 34 and line 17, and conduit 6 extends through shaft 10 to a port 35. Piston 15 is restrained from rotation by pins 36A engaging a slot 36. Thrust bearings 37, 38 locate shaft 10 longitudinally.