Estimation of the height of caved and fractured zones above a longwall panel along with the stability onditions of the goaf area are very crucial to determine the abutment stresses, ground subsidence, and face upport as well as designing the urrounding gates and intervening pillars. In this work, the height of cavingfracturing zone above the mined panel is onsidered as the height of destressed zone (HDZ). The long-term stimation of this height plays a key role in the accurate determination of maximum ground surface ubsidence and the amount of transferred loads towards the neighbouring solid sections. This paper presents new stability analysis model of caved material system in the goaf area. For this aim, a heoretical energybased model of HDZ determination in long-term condition is developed. Then the stability condition of the aved material system is investigated using the principle of minimum potential energy. On the basis of the ctual data athered from the literature, the unstable time period of the caved material system is also alculated. Moreover, the effects of time- and temperature-related parameters and constant coefficients as ell as their inherent relations with HDZ are valuated. Furthermore, sensitivity analysis shows that the two emperature-related constants material constant and time are the most effective variables in HDZ, and the lope of material hardening is the least effective one. The estimated HDZ and the stability time of the caved aterials can be successfully applied to determine the induced stress and the maximum surface subsidence, espectively, due to longwall mining.
