| The problem of slope instability and failure widely exists in nature and all kinds of engineering,among which landslide is the most common failure form and causes the most harm.Cantilever anti-slide pile is one of the main treatment measures in all kinds of slope protection and landslide treatment engineering.At present,in its application process,there are more experience components of design theory,pile bearing characteristics are not clear.Secondly,because the cantilever anti-slide pile structure is in the underground environment with corrosive medium for a long time,so in its service period will inevitably produce damage accumulation and performance degradation.Therefore,it is one of the important and urgent research topics to carry out in-depth research on the long-term performance of cantilever antislide pile.Based on the key project of Chongqing Natural Science Foundation "Long-term Performance Research on concrete deterioration and anti-slide pile under the action of thrust coupling",this thesis adopts the research method of physical model test and numerical simulation.The main work is as follows:(1)Carrying capacity test of cantilever anti-slide pile was carried out,and the law of internal force deformation and crack propagation was obtained.According to load-top displacement curve,the loading process of cantilever anti-slide pile is divided into three stages: uncracked stage,working stage with cracks and failure stage.When the pile is damaged,the cracks are distributed between 110 mm above the sliding surface and 150 mm below the sliding surface.The cracks are transverse tension cracks and cable-stayed cracks,extending "radially" from the tension zone to the compression zone in the two layers of the pile.The bending moment of cantilever anti-sliding pile is nonlinear in the long direction of the pile.There is a peak moment at the sliding surface,and the bending moment curve shows an obvious unipeak phenomenon with the increase of load.(2)A cantilever anti-slip pile model considering the bond and slip effect of reinforced concrete is established,and the crack development law of anti-slip pile and the stress and displacement distribution law of the bond layer of reinforced concrete are obtained.The error of bearing capacity calculated by cohesion model is reduced by11.4% compared with embedded model,and the distribution pattern of fracture damage zone is in good agreement with the test.It is found that the strain coordination of reinforced concrete in anti-slide pile is the weakest at the sliding surface and increases with the increase of load section height.Secondly,the bond stress in the anti-slide pile is positively correlated with the load,and reaches the maximum value at the sliding surface.When the tension reinforcement enters the yield state,the free section will produce obvious bond slip phenomenon.(3)The degradation law of bearing property of anti-slide pile under acid rain erosion environment is revealed.The bearing capacity of anti-slide pile under acid rain erosion is positively correlated with the compressive strength of concrete.When the acid rain erosion period reaches 120 days,the bearing capacity of anti-slide pile decreases by 1.53%.Considering the uniform corrosion of steel reinforcement,five numerical models with different corrosion degrees of anti-slide pile are established.When the corrosion rate of steel reinforcement reaches 6.79%,the bearing capacity of anti-slide pile decreases by 8.01%.When the bond strength decreases by 10%,the bearing capacity of anti-slide pile decreases by 4.48%.The influence degree on the bearing capacity of anti-sliding pile is as follows: mechanical property of reinforcement > bond strength > concrete strength.The results show that the bond stress in the anti-sliding pile decreases with the increase of corrosion rate,the axial displacement increases with the increase of corrosion rate,and the strain coordination between reinforced concrete on the sliding surface weakens with the increase of corrosion rate.Finally,based on the calculation results of the cohesion model,the formulas for calculating the stiffness and bearing capacity of the corroded steel anti-slide pile are fitted.The calculated results are in good agreement with the existing experimental data. |
