Rockexperimentresultsindicatethattheload/unloadresponseratio(LURR)ofrocksexpressedviastrainenergymayhavesingularornegativevalueafterthestressintherockreachesitsmaximumbeforerockfailureorwhentherockgoesintothestrain-weakeningphase.Theuniversalityofthisphenomenonisdiscussed.ExpressedviastrainorstrainenergyandthetraveltimeofPwave,thevariationformofthereciprocalofLURRduringtheprocessofrockfailurepreparationisderived.TheresultsshowthatafterasharpdecreasethereciprocalofLURRreachesitsminimumwhenthemainfractureoftherockisabouttoappear.Thisfeaturecanbetakenasanindicationthattherockmainfractureisimpending.