Experimental Study of Critical Anchorage Length of Tensile-type Rock Anchor

According critical anchorage length theory，and different pull out test with different length rock bolts in three different strength concretes，which include low，middle and high，experimental condition and distinguish method of tensile type rock anchor critical anchorage length in rock were studied，with other studying results，experiment condition and distinguish of critical anchorage length were studied future.The results showed that peak value stress transfer and zero value shear stress transfer appeared almost at the same time，the space distance between peak value and zero value is critical anchorage length.Critical anchorage length of tensile type rock anchor is ubiquitous，and in the same experiment situations, the same safety value of critical anchorage length could be obtained，and engineering design is reasonable based on it.