Study On Long-term Durability Of Rock-Soil Prestressed Anchorage Structure Under Coupling Of Fatigue Load And Corrosion

Rock and soil anchorage is an important branch of geotechnical engineering.Using prestressed anchorage structure in the geotechnical engineering,can effectively control the deformation and maintain the system stability of rock and soil.Due to the good reinforcement effect,simple construction,safe and reliable,low cost,prestressed anchorage structure is widely used in slope,foundation pit,tunnel,underground cavern,mine,dam and other construction projects.However,the prestressed anchorage structure has been subjected to stress during operation,and the surrounding environment is complex,there are a lot of corrosive media and stray current,easy to make steel corrosion.So the prestressed anchorage structure will be gradually destroyeddue to load and corrosion,resulting in its durability gradually reduced,and ultimately failure.Therefore,it is necessary to study the durability of prestressed anchorage structures.In this paper,the durability of geotechnical prestressed anchorage structure under the coupling of fatigue load and corrosion was studied by means of laboratory test,theoretical analysis and numerical simulation.The effects of fatigue load and corrosion on the properties of steel bars were analyzed,and the failure and variation of internal anchors were simulated by software.The specific research contents are as follows:(1)The fatigue and corrosion tests of the steel bars were carried out for a certain period of time.The bars were divided into several groups and numbered,each group of steel were applied to the different number of fatigue stretching and placed in different acid-base environment.Then the effects of fatigue load and corrosion on the properties of the steel bars were obtained.Select the typical steel bars to do tensile fracture test.The fracture behavior of the steel bar was observed by scanning electron microscopy(SEM).The mechanical properties and fracture characteristics of rebar under the coupling of fatigue load and corrosion were analyzed.(2)The numerical model of prestressed anchorage structure under the action of fatigue load and corrosion coupling and fatigue load alone was established by PFC2 D program.The shear stress of the anchor-grouting structure,the axial stress and the displacement field of the internal anchor section under the two conditions are compared and analyzed.The mesoscopic regularity of the bond failure of the anchor section under the coupling of fatigue load and corrosion is obtained.(3)The PFC2 D program is used to establish the numerical model ofthe prestressed anchorage structure under the coupling of fatigue load and corrosion.The effects of grouting structure strength,surrounding rock mass strength and length of internal anchor section on the durability of the prestressed anchorage structure are studied respectively,and the measures to enhance the durability of the prestressed anchorage structure are put forward.