Abstract: A piezocone for measuring the soil's resistance to penetration and pore water pressure while being advanced into the ground by a twenty ton hydraulic cone penetrometer rig. The low pressure piezocone includes a friction sleeve and a conical tip attached to the lower end of friction sleeve. The conical tip develops the cone resistance. The friction sleeve is an isolated cylindrical sleeve which measures the resistance of the soil as the sleeve passes through the soil. The pore water pressure is measured by a porous element mounted in the conical tip of the piezocone and a pressure transducer mounted in the cylindrical friction sleeve of the piezocone. The measurements including pore water pressure, cone resistance and the soil resistance are supplied to a computer which includes a Piezocone Dissipation Analysis program for processing the piezocone measurements to generate dissipation curves for each depth at which the piezocone provides hydrogeologic site characterization data.

Abstract: A driver circuit having logic circuitry which controls the coil and assoced contacts of a four pole double throw relay. The four pole double throw relay is toggled such that a large latching current flows through a first of a pair of solenoid coils of the magnetic-latching solenoid, while a relatively small current flows in the second solenoid coil of the magnetic latching solenoid in an opposite direction. Toggling the relay's coil causes the latching current to now flow through the second solenoid coil of the valve, while the relatively small current flows in the first solenoid coil of the magnetic latching solenoid again in the opposite direction.