Study On The Influence Of Fiber Mortar Onthe Anchoring Performance Of Prestressed Anchor Cable

Prestressed anchor cable is widely used in slope engineering,tunnel engineering,mining engineering and foundation pit engineering due to its ability to give full play to the characteristics of rock and soil strength,small space occupied,deep active support,low cost and simple operation.However,due to the poor anti-tensile performance of the cement mortar used in practical engineering,the cement mortar in prestressed anchor cable is prone to crack under the action of load,which leads to the corrosion of steel strand and ultimately affects the durability of the prestressed anchor cable and greatly limiting the development prospect of the prestressed anchor cable.Therefore,it is urgent to study the properties of new grouting materials.Polypropylene fiber mortar is a new grouting material by incorporating a certain amount of polypropylene fiber into a certain proportion of mortar.The polypropylene fiber mortar not only has high self-strength but also enhance the anti-cracking ability of the cement mortar,improve the bonding ability between the mortar and the hole wall and improve the stress characteristics of the anchorage section,so as to improve the anchoring effect and long-term performance of the cable.In this paper,theoretical analysis,physical model test and numerical simulation were combined to study the anchoring performance of tensile anchor cables under the conditions of polypropylene fiber mortar and ordinary mortar.The following conclusions are as follows:1.The anchorage mechanism of tension-type cable was summarized by referring to the literature.With Kelvin displacement solution as the foundation,the load transfer law and the shear stress distribution of the anchorage section of tension-type anchor cable were obtained.On the basis of that,the elastic modulus of rock mass and diameter of anchor pole on the influence of the anchoring force were analyzed,and then focus on common failure forms of anchor cable and the fracture surface.2.The influence of polypropylene fiber on the mechanical properties of cement mortar was summarized,and the influence of fiber mortar on the shear strength and the distribution of shear stress in the anchorage section was further discussed.Fiber incorporation can strengthen the crack resistance and fracture toughness of the grouting material,which is of great significance to the durability improvement of the anchoring system.3.Typical high slope protection engineering in guizhou mountain area as the prototype,and select the appropriate similarity ratio,carried out tensile-type anchor cable anchorage performance of physical model experiment with the ordinary mortar and polypropylene fiber mortar,then analyzed and got the influence of polypropylene fiber mortar to shear strength and shear stress distribution curve of the tensile-type anchor cable anchorage segment.The experimental results showed that the incorporation of fiber can alleviate the stress concentration of anchorage section,improve the anchoring ability and the durability of cable in high stress state.4.Using FLAC3 D to carry out numerical simulation of prestressed anchor cable anchorage performance with fiber mortar,axial force and shear stress distribution law of grouting materials were obtained.the calculation results are consistent with the experimental data of the fourth chapter,which further verify the reliability of the results obtained in this paper.