Bearing Capacity Predicting Method on Mortar-Rock Interface of Compression Type Rock Anchor

To predict bearing capacity on mortar-rock interface of compression type rock anchor, the failure model of fixed anchor length is established. The maximal shear stresses on the interface in front of the bearing plate are determined based on tests. The relation of maximal shear stress and fixed anchor length is assumed. Double exponential function curves are adopted to simulate the ultimate state of the fixed anchor length. Two parameters are introduced to adjust the curve shape. According to the results of the field test, the values range of the parameters in soft rock is determined. After comparing ultimate bearing capacity measured in test with predicting value, it is shown that the empirical formula can calculate the bearing capacity of fixed anchor length reasonably. Compression type rock anchors have more capacity than ordinary tension type anchors and the capacity is convergent gradually with fixed anchor length increase.