Analysis of Stress and Conical Body Characteristics of Anchorage Body Under the Action of Pretensioned Bolt

In the support of prestressed anchor in coal mine roadway, the formation of cone body in anchorage body is an important reason for prestressed anchor to play a role. In order to investigate the formation laws of the conical body in the anchorage body, ANSYS was used to build anchorage body model containing a single anchor bolt. Then, pre-tightening force and surrounding rock pressure were applied on the anchor bolt and conical body respectively. The stress state inside the anchorage body and the formation of the conical body were studied. The results show that the horizontal stress inside the anchorage body shows a concave shape, i.e., the horizontal stress is higher in both end surfaces of the anchorage while that is smaller in the middle of the anchorage body. The conical body shows a “fist” shape. In some areas near the end of the anchor bolt, the anchorage body is subjected to tensile stress. The angle between the contour line of the conical body and the anchor decreases with the increase of the surrounding stress while that increases with the increase of the pre-stress. However, the height of the surface of the conical body increases and decreases with the increase of the surrounding press and pre-stress separately.