Study On The Bond Mechanism Between Polyurethane Grouting Material And Concrete In Aqueous Environment

At present,the total length of domestic urban drainage pipeline is more than 1million kilometers.With the growth of operation years,the safety of the pipeline is affected by the subsidence of the pipeline caused by the settlement of the foundation."Polyurethane(PU)grouting material repair technology" is a new non-hydrophilic nonexcavation rapid repair process.Its principle is to inject polyols and isocyanate into the area to be repaired according to a specific ratio,and realize the rapid sealing of leakage and settlement after the material self-expansion.Polyurethane(PU)grouting repair technology has the advantages of low density,fast strength improvement,nonhydrophilic,no pollution,rapid generation of strong expansive force,etc.In recent years,more and more applications in the consolidation of loose soil,settlement infrastructure repair,fractured rock reinforcement,dam or underground building seepage prevention and other fields.However,in the process of polyurethane(PU)grouting material flow expansion,the underground concrete pipeline is in a complex groundwater environment,and the concrete surface humidity will affect the polymer curing process.When the polyurethane(PU)grouting material curing is completed,the force and deformation of the pipeline will change under the action of polyurethane.Since the compressive properties of PU grouting material and the bonding mechanism between PU grouting material and concrete binary body interface are not clear,the bearing capacity and deformation of the reinforced structure cannot be accurately evaluated.Therefore,on the basis of experiments,theoretical research is carried out in this thesis to analyze and study the compression process and compressive characteristics of polyurethane(PU)grouting material,the bond failure type and failure process between polyurethane(PU)grouting material and concrete binary body.At the same time,the uniaxial compression simulation of PU grouting material and the simulation model of shear failure between PU grouting material and concrete interface are completed.The following is the specific research content:(1)The microstructure of polyurethane(PU)grout material was amplified by scanning electron microscopy,uniaxial compression experiment of PU grouting material was carried out,and the compression process and compressive characteristics of the polymer were analyzed from multiple dimensions by combining acoustic emission technology and digital image technology(DIC),and the compressive strength-strain damage constitutive relationship before yield was proposed.(2)ABAQUS finite element software was used to simulate the uniaxial compression process of polyurethane(PU),and the experimental results were compared and analyzed.(3)The interfacial meso-structure of polyurethane(PU)grout material-concrete binary was amplified by scanning electron microscopy,and the direct shear experiment combined with digital image technology(DIC)was carried out from the macroscopic and microscopic perspectives to determine the main factors affecting its bond strength.(4)ABAQUS finite element software was used to simulate the direct shear failure process of PU-concrete binary interface,and the experimental results were compared and analyzed.