Tension model test research on grouted bolts foundation in jointed rock masses for transmission lines

According to the character of grouted bolts foundation in jointed rock masses for transmission lines, the model tests are designed based on the similarity theory. The model tests are carried out with focus on the following five factors: elasticity modulus of rock, elasticity modulus of mortar, trace lengths and joint inclination angle in rock mass, embedding depth of the bolt in the rock mass on four different levels of every factor. The experimental results reveal that the elasticity modulus of rock is the most important and sensitive factor influencing the pullout strength of grouted bolt foundation, and the factors next are embedding depth of the bolt in the rock mass, joint inclination angle in rock mass, elasticity modulus of mortar and trace lengths in rock mass. The destruction forms in the model tests are mainly shear failure and split failure. The force transferring mechanism of the bolt is also analyzed. It is concluded that the bond strength between the mortar and the rock, the mortar and the bolt are the main factors controlling test results and affecting the pullout strength of the bolt and failure status. It should be paid more attention to control the quality in the procedure of construction.