The Research On Roller Compacted Concrete Layer Crack Destructive Process Under The Action Of Water Pressure

Roller compacted concrete dam is layered constructed by RCC concrete, the damconstruction plane is the weak link, it may become the seepage concentration channel andinstable weak surface, and impacts strength and stability of the dam body, so to carry outthe research on RCC layer crack and fracture characteristics under the water pressure withthe coupled action of the complex stress field has important theoretical significance andreference value. Due to the concrete fracture test under the action of water pressure isdifficult and complex, so numerical simulation has become another method to researchroller compacted concrete fracture mechanism under the action of water pressure. Byestablishing the mathematical or physical model, adopting all kinds of finite elementsoftware to numerical analysis to draw the breaking characteristic of roller compactedconcrete under the action of water pressure, which can make up the barriers caused by testdifficulty in this study.The software RFPA is adopted to develop the numerical simulation on RCC under theaction of tension, tension and shear in this paper, the mainly work is done as follows:(1) The tension numerical simulation on three kinds of roller compacted concretelevel models under the action of pure water pressure, water pressure and mechanical loadis developed. Loading methods are divided into two main classes: one class loading way ispure water pressure effect, initial value of water pressure are0MPa,0.1MPa,0.2MPa,0.3MPa, and water pressure increment is0.02MPa; Another type of loading way is waterpressure and mechanical load joint action, initial value of water pressure are0MPa,0.1MPa,0.2MPa,0.3MPa, water pressure increment is0MPa, mechanical load is appliedwith the form of displacement load, and the initial value is0mm, increment is0.002mm.(2) Through analyzing the tension numerical simulation results, it is concluded thatthe water pressure, tension stress and elastic modulus distribution in the process of thecrack propagation, the changes of tensile stress and water pressure on the crack point and instability point along the crack propagation direction, and the water pressure distributionin the crack tip. The cracking load, ultimate load, critical crack length, the crack steps andinstability steps number of all kinds working conditions are obtained. The crack toughness,instability toughness and cohesive toughness of all kinds conditions are calculated. Thecrack propagation softening curve and the formula of all kinds working conditions areobtained.(3) The tension and shear numerical simulation on three kinds of roller compactedconcrete level models under the joint action of water pressure and mechanical load isdeveloped. Loading methods are as follows: initial value of water pressure are0MPa,0.1MPa,0.2MPa,0.3MPa, and water pressure increment is0.05MPa; mechanical load isapplied with the form of displacement load, and the initial value is0mm, increment is0.002mm. the distance of mechanical load loading point and precast crack are0mm,20mm,40mm.(4) Through analyzing the tension and shear numerical simulation results, it isconcluded that the water pressure, shear stress and elastic modulus distribution in theprocess of the crack propagation, the changes of shear stress and water pressure on thecrack point and instability point along the crack propagation direction, and the waterpressure distribution in the crack tip. The cracking load, ultimate load, critical crack length,the crack steps and instability steps number of all kinds working conditions are obtained.The crack toughness, instability toughness and cohesive toughness of all kinds conditionsare calculated.