| As a significant part of the modern geotechnical anchoring system,the performance of the anchor supporting structure is directly related to the safety of the support engineering.Due to the complicated working environment of the anchor structure and the influence of external environmental factors,corrosion of steel bars in the anchor structure is common in practical engineering.Meanwhile,the anchoring performance of the rusted mortar anchor structure is also subjected to various dynamic loads.The bonding performance of the anchor structure under the situation of rust and dynamic load is different from that under the situation of no rust and static load.Therefore,it is important to study the dynamic bond performance of corroded mortar anchors and analyze the dynamic response,which is of significant reference for designing the anchor support structure and evaluating the anchoring performance of the anchors in service.This paper is funded by Liaoning BaiQianWan Talents Program candidate selection projects(2014921061)and Dalian Innovation Supporting Plan for Advanced Talents(2015R073).The experimental study on dynamic bond performance of rust mortar anchors under different loading frequency was carried out.The main contents of the research are as follows.(1)An indoor test for studying the dynamic bonding performance of corroded mortar anchors was designed.The model composed of annular cylinder of concrete,mortar body and deformed steel bar was a composite structure to simulate the tensile-type anchor in practical engineering.Electrochemical corrosion was adopted for the rapid corrosion of the steel bar inside the specimens in order to simulate the corrosion state of the anchor steel bar.With the steel bars wire-electrode cutted and the strain gauges attached inside,the steel strain at each point of the anchorage section was dynamically collected during the loading procedure.High-precision displacement sensors were arranged on both ends of specimens for recording the real-time displacement data.With the input of different frequency,MTS cyclic loading equipment was used to simulate the dynamic load process applied to mortar anchors.(2)The dynamic bonding properties of corroded mortar anchors were studied by dynamic pull-out test.Based on the measured data of specimens,the bonding stress of the steel bars-mortar interface was fitted by solving the matrix equation.The stress-strain curve and load-slip curve were also plotted.The dynamic response of the bonding performance during loading procedure was analyzed.The influence of the loading frequency,corrosion degree and anchor length on the bonding performance of mortar anchors was investigated.(3)The dynamic bond-slip constitutive relation of corroded mortar anchors was established.Based on the average bond stress and relative slip,the basic bond-slip constitutive relation of corroded mortar anchor was established.The bond stresses under different loading frequency were fitted,and the dynamic influence coefficient of mortar anchor was obtained.Based on the bond stress-slip relationship of each point in anchorage section with different corrosion degrees,the formula of the position function was derived.Finally,according to the basic bond-slip relationship,the dynamic influence coefficient and the anchorage position function,the dynamic bond-slip constitutive relation of the corroded mortar anchor regarding to anchorage position was established. |
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