Study of bolt anchoring effect based on self-bearing characteristics of roadway surrounding rock

The current researches on bolt anchoring effect are rarely concerned with self-bearing characteristics of whole anchorage surrounding rock. For its sensitive response to mechanical changes of surrounding rock bearing structures, tangential stress σθ curve with different bolt lengths and different bolt strengths is researched, which can provide important references to research the bolt anchoring effect. The σθ curve shape of whole anchorage roadway is related to the anchorage end position in elastic and plastic surrounding rock. When bolt anchorage end is located in the plastic zone of surrounding rock, the peak value and its corresponding position of σθ curve are slightly influenced. With the increasing of bolt anchorage end depth in the elastic zone, distribution curve of σθ will have internal and external peak values from the surface to the depth of anchorage surrounding rock gradually; and its alternative elastic and plastic zones gradually appear. And bolt strength should match the self-bearing strength of surrounding rock. Accordingly, a new method to determine the bolt anchoring effect based on the double peak values of σθ curve of anchorage surrounding rock is put forward, which can well explain the problems of canceling the systematic anchor bolts in weak strata.