Abstract: In order to study the reasonable assessment method of the safety coefficient of tunnel-type anchorage, three different methods—stress integration method, displacement load curve method and plastic area-load curve method are used to solve the uplift stability coefficient of tunnel-type anchorage. And the specification value is also given to make a comparison with the values obtained from the three methods. Results show that the stability coefficient given by specification method is comparatively small because this method neglects the clamping effect of rock to anchor. The value of safety coefficient calculated by this method is only 2.60. And stress integration method takes the stress field corresponding to the design load as the calculation stress, in which case the clamping effect is out of action. Therefore, the coefficients calculated by this method are close to the value of specification method. The safety factor calculated by this method is 2.64 when the failure mode of tunnel-type anchorage is interface failure. And the value is 2.88 while the failure mode is rock failure. In addition, the safety coefficient obtained from both plastic area-load curve and displacement load curve methods are 6.50, the biggest value of all methods. Because the rock and anchor contact each other closely and the clamping effect works effectively under the maximum permitted load. Last but not least, the uplift safety coefficient of tunnel-type anchorage with the clamping effect into consideration can be calculated when the bearing force of interface can be calculated by the ultimate lateral resistance.

Key words: tunnel anchorage, uplift stability coefficient, stress integration method, plastic area-load curve, displacement load curve, clamping effect