Jinchuan mine has complex geological conditions, structural development. The exploitation is of great difficulty because of the broken orebody, high geostress, and poor rock mass stability. Line 14 ventilation shaft is located in the footwall, whose depth is 718m, the diameter of borehole excavation is 7.1m, and the net diameter is 6.5m. On March 9, 2005, the well happened the rock falling. The massive collapse appeared until March 21, and falling risk area is about 11000m³. All falling rubble blocked the 500-meter borehole within a few days.

Self drilling anchor bolt system is mainly used for slope stabilization, foundation with micropiles and tunneling, and it’s also widely used in the railway system, metro project, etc. It can be installed in sites with weak rocks, loose soil, weathered layer, sand with stone layer and so difficult to create a hole in complex formation. The unconsolidated ground condition favor the self drilling anchor bolt technique for fast and simple method of installed compared to the traditional method.

Drill the R38N self drilling anchor bolt to the designed length with YT-28 type wind-driven rock drill in design position of the wall. The self drilling anchor bolts and the drill bits should be checked whether they are smooth before drilling. The drills should open wind, water, and then drilling. When the self drilling anchor bolts were drilled to the designed position, they should be cleaned with high pressure air and high pressure water, and checked again. Self-drilling anchors should be exposed 300mm ~ 350mm.

Type	Length(m)	Spacing(m)	Sodium Silicate Concentration	Cement Mark
R38N	8	2*2	1:1~1:0.6	P.O.32.5R