Abstract:The reverse-pull method is currently the most widely used method for detecting the effective prestress under the anchor. The inflection point of the test curve is used to determine the effective prestress under the anchor. In recent years, many scholars have found that there is a sudden load drop at the inflection point of the test curve. Therefore, the causes of the sudden change segment in the test curve of the reverse-pull method are discussed. The viewpoint is proposed that the reverse pull load needs to overcome the anchorage grip force during the clamping piece pulling-out process, which leads to the generation of the sudden change segment. The gripping force of anchorage is mainly composed of the friction resistance of the anchor ring and the clamping piece and the mechanical bite force of the anchor ring and the clamping piece. At the same time, in order to obtain the influencing factors of the gripping force, a finite element model is established to analyze the gripping force of the single-cone-hole wedge-type anchorage. The method for extracting the gripping force of the finite element model is designed and expounded. Through the finite element model, three factors of control tension force, friction coefficient and tapered-hole amount are obtain to affect the gripping force of anchorage are obtained. And the correlation curve of the control tension force and friction coefficient with the gripping force is fitted. It is concluded that the control tension force and friction coefficient are positively correlated with the gripping force.
