Study On Stress Mechanism And Design Optimization Of Anti-floating Bolt Of Underground Engineering

Anti-floating anchor is a kind of anti-floating measure of underground structure of building engineering.Currently,the research direction of anti-floating anchor mainly focuses on mechanical properties,construction design,bearing capacity and so on.The study on the overall stress mechanism of anti-floating anchor and the optimization of anti-floating bolt for large underground engineering is rare,the long term monitoring data of the internal force of anti-floating bolt are very few.In view of the above problems,through numerical simulation,field anchor drawing test and long term monitoring method of anchor internal force,To understand the stress state and change law of the anti-floating anchor,and to provide the basis for the optimum design of the anti-floating anchor.The main research methods and contents include:①Numerical simulation of anti-floating anchor:Numerical simulation of anti-floating anchor:combining with practical engineering,studying and selecting the appropriate parameters,setting up a standard model,satisfying the purpose of auxiliary optimization design.②Drawing test of anti-floating bolt:Through the Q-S curve,analyzing the deformation characteristics of the anti-floating bolt,studying on the force mechanism of anti-floating anchor.③Internal force monitoring of anti-floating anchor:Installing internal force monitoring device on anti-floating anchor in practical engineering,and solving the problem of data reliability and transmission methods in the long term monitoring of internal forces.Through the analysis of the internal force-time curve,analyzing the influence of the construction schedule on the internal force of the anti-floating bolt.④Study on the force mechanism of anti-floating anchor:By analyzing the results of numerical simulation,the results of the field drawing test and the monitoring results of the internal force of the bolt,studying on the stress state of anti-floating anchor in underground engineering,force deformation and the change law of internal force with time,analyzing the stress and deformation characteristics of anti-floating bolt and its influencing factors.⑤Optimum design method of anti-floating bolt:using the method of numerical simulation as auxiliary,field test and anchor internal force monitoring as a verification method,the design optimization method of anti一floating bolt is presented.Through the above research,the force mechanism of anti-floating bolt is analyzed and verified,the method of optimizing design is summarized,the measured data of internal force change of anti-floating anchor bolt are obtained,.The main conclusions are:Because of the difference of load between the main building and the podium,the anti-floating anchor bolts in different positions will be different in force,so the anti-floating anchor bolts should be considered in design and construction;It is suggested that the optimum design method of anti-floating anchor is mainly based on the code,with the aid of numerical calculation method,the calculation accuracy can be improved,and the force difference of anti-floating anchor can be considered;Because of the variation of the upper load and groundwater level with the construction progress,the axial force of the anti-floating anchor will undergo three stages:the stage of axial force weakening,the stage of axial force strengthening and the stage of stability.