Abstract: In order to determine the vulnerable position and the limit water head value of the artificial dam body of the underground reservoir in the coal mine,the mechanical model of the artificial dam body was established,and the stress distribution function of the dam body was derived based on the thin plate theory of elastic mechanics.Lijiahao underground reservoir was a reference,the theoretical formula was verified and compared by FLAC3D numerical simulation software,and the dam body plastic was compared by using Mohr Coulomb model and DP model respectively.The results show that the first failure position of the dam body is the center of both sides of the front,followed by the center of the bottom of the front,the center of the top of the front and the center of the back.The use of the Mohr Coulomb model in FLAC3D is consistent with the damage analysis of the dam body,which more accurately reflects the damage characteristics of the dam.For the failure prediction of the dam body,the safety factor of the Moor Coulomb model is higher than that of the DP model.Taking the damage of the Moor Coulomb model as a reference,the limit water head value of the artificial dam of Lijiatun is determined to be 24 m.

Key words: groundwater reservoir,artificial dam,thin plate,software FLAC3D