Abstract: The rock mass in the drilling tunnel foot wall in Baluba copper Mine (CNMC Luanshya Copper Mines Pls.) is broken, its feature of weathering making the rock easily collapsed, and it is susceptible to argillitizated and disintegrated contacted with water.The traditional grouting bolt can not satisfy the requirement of tunnel stability, so the pre-stressed bolt-provide active support was adopted.The excavation and support process was stimulated by FLAC^3D, and analyzing and comparing the different mechanical principles between full-length pre-stressed anchored grouting bolt and general grouting bolt in controlling the tunnel deformation.The numerical result shows that pre-stressed bolt can reduce subsidence of the roof more than 10 mm, which is about 2 times as long as general grouting bolts.Therefore, it is necessary and effective to use the pre-stressed grouting bolt in area of broken rock.Finally, to achieve better supportive effect, shotcrete must be injected to roof and side walls, which is called the combined support.

Key words: Broken rock mass, FLAC3D, Pre-stressed grouting bolt, General grouting bolt, Subsidence of tunnel roof