As supporting engineering product, rock bolt plays an important role in the safety of the project, at the beginning of the project design, the selection of rock bolt is especially important, according to the actual geological conditions and the number of years of engineering, select the appropriate safety factor is to find the balance between security and investment, following the selection of rock bolt safety principles and standards of each country making a simple comparison.
The safety factor of anti-pull rock bolt is the ratio of ultimate pullout force and tensile bolt design value (work load).The rock bolt pull-out of safety coefficient depends on the lifespan of rock bolt, conditions of use, unstable factors in the design of structure and risk; When the work stress level of anchor rod body is greater than the tensile strength of the rod body 60%, there will be a larger stress relaxation, also in the presence of high tensile strength of muscle mass caused by stress corrosion.
The pull-out safety factor of rock bolt
|Country name||Specification name||Minimum safety facto|
|Temporary anchorage||Permanent anchorage|
Specification for design and construction of soil anchors
|1.4, 1.6, 1.8||2.0|
|1.4, 1.5, 1.8||2.0|
Ground anchor development recommendations
|1.4, 1.6, 2.0||2.0|
|America||PT1 Recommendations of the prestressed soil anchor||–||2.0|
|The international association of prestressed concrete||FIP Prestressed grouting anchor design and construction specifications||–||2.0|
Design and construction of soil anchor