DEVELOPMENT OF AN INSTRUMENTED SUBSOILER TO MAP SOIL HARD-PANS AND REAL-TIME CONTROL OF SUBSOILER DEPTH

Abstract

An instrumented subsoiler shank was designed and built to measure the soil resistance whilemoving through the soil and for automatic control of the depth of several standard subsoiler shanksmounted on the same frame. Three load cells measure the resultant magnitude and direction of the soilreactions on the shank. Two load cells measure forces perpendicular to the straight shank with aconstant distance between them and another load cell measures the force along the shank. The twoperpendicular load cells are cantilevers with one side mounted to the center of the shanks width andthe other side connected to wheels running inside a hollow beam. The wheels enable the shank to bemoved up and down for different depths with the aid of a hydraulic cylinder. The hydraulic cylinder isconnected to the upper edge of the shank by the lengthwise load cell. The resultant force on the shankis calculated by using the three measured forces, their directions and locations. The instrumented shankwas calibrated and tested in the field. While preliminary in nature, the results indicate that when theshank tip is above a soil hardpan, the soil force on the tip acts upward, and becomes negative when theshank tip is below the hardpan. These results indicate that it may be possible to determine the depth ofthe hardpan by observing when the vertical force on the shank tip passes through zero as the shankdepth is cycled above and below the hardpan.