When operating a subsoiler or deep chisel tine to shatter a dense subsurface hardpan, if the working depth is increased beyond the 'critical depth':
Options:
(A) Soil is no longer lifted upward in a crescent failure pattern, but is instead pushed sideways in a compacted two-dimensional plastic flow, drastically increasing specific draft without increasing surface soil shattering
(B) Draft force becomes completely independent of working depth
(C) Specific draft drops to zero due to spontaneous soil liquefaction
(D) The vertical force shifts from downward suction to an uncontrollable upward thrust
Answer Key:
A
Step-by-Step Solution & Explanation
Beyond the critical depth, soil confining pressure prevents upward crescent shear failure. The tine creates subterranean compaction grooves via lateral plastic flow, sharply increasing specific draft ($N/cm^2$) with negligible shatter benefit.