In soft rocks or soil, the fiction force of self drilling bolt’s hole wall is less than the bond stress of slurry, so the ultimate load of self drilling bolt depends on the biggest fiction force of anchorage section’s stratum.
Besides the properties of stratum, it also concerns with construction method and grouting quality. If technology is good, the friction force of self drilling bolt’s hole wall depends on the shear strength of surrounding soil.
When calculating the anchorage length, the shear strength of self drilling bolt’s hole wall plays a quite important role, but the calculated value is only assessment, which will be a reliable basis only after testing on the spot. Safety factor needs to be considered when the ultimate load is depending on self drilling bolt’s bearing force.
In conclusion, choosing self drilling bolt with appropriate ultimate load should base on different geological conditions, which finally aims to support project and reach stable effect.