of the shallow tectonic hierarchy of the crust，and also have an important influence in engineering stability analysis．Using the Ansys numerical modeling platform and referring to the granite burst test，the authors simulate the

characteristics of unloading joints in granitic plutons during the uplifting process to the surface at a rate of 0. 025 s /MPa，0. 05 s /MPa，0. 1 s /MPa，and 20 s /MPa，respectively． The modeling results show that the formation of unloading joints in granitic plutons is mainly related to the unloading rate of confining pressure． When unloading at 0. 025 s /MPa，the granite has an obvious stratification． When unloading more than 0. 025 s /MPa，the granite

cracks violently，showing the characteristics of fragmented shape and weak stratification． The starting point of horizontal unloading joints appears at 550 m underground，while vertical unloading joints appear at 700 m underground．

The unloading of the overlying plutons is the main factor for the appearance of unloading joints of granitic rocks that are exposed underground． When the granites approached and are exposed to the surface，the horizontal unloading joints in granitic plutons are significantly affected by weathering and denudation． In addition to weathering，the vertical unloading joints are also affected by the weight of the granitic plutons．