Seismic Dynamic Response Research On Steel Fiber Reinforced Concrete In Tunnel Lining Structure

Steel Fiber Reinforced Concrete(SFRC) material has good flexural tensile performance,crack resistance and after-crack toughness. Although it has already obtained a certain degree of research and application in tunnel and underground engineering,but its application in tunnel and underground structure shock absorption research is not in-depth enough. This thesis, based on a highway tunnel,Yun Shan tunnel, and a high-speed railway tunnel, Da Liang tunnel,combined with underground structure dynamic time-history analysis method, studies on the seismic dynamic response of the hole body of tunnel. This mainly for the following:1.Discusses the two main types of fiber-reinforcement theory,namely the composite material theory and the fiber-spacing theory, and compares the tensile strength calculation formulae of each theory, and results show that the two theories has some consistency in explaining fiber- reinforcement mechanism;2.As to the bearing capacity limit state analysis of Steel Fiber Reinforced Shotcrete(SFRS)and ordinary shotcrete,assuming that the after-crack tensile stress of SFRS tension zone is ftilly borne by steel fiber,the required thickness of section is compared respectively under same ultimate bending moment, and the calculation results show that the SFRS thickness is thinner;3.Carries out SFRC beam, with incision, compressing-bending toughness test,studies the stress-strain constitutive relation in the tension zone of SFRC, calculating tensile strength of two types of SFRC specimen. Results show that with the certain dosage of steel fiber and the certain strength of concrete matrix,tensile strength of the tension zone of SFRC is closely related to Steel Fiber Length-Diameter Ratio(SFLDR). Compared to SFRC specimen that SFLDR is 45.5,the SFRC specimen that SFLDR is 60 performs better. In addition, the compressing-bending toughness test specimens have adopted different geometries and sizes,the influence of size effect needs to be considerd while calculating tensile strength;4.In this thesis, numerical analysis of seismic dynamic response of the hole body of Yun Shan tunnel and Da Liang tunnel, is carried on separately in horizontal and vertical direction.Bedrock input of seismic wave needs filtering and baseline correction, and WenChuan earthquake wave is applied in horizontal direction, the Japan Kobe earthquake wave is used in vertical direction. Analysis results show that:(1) When bedrock horizontal vibrating, as to the horizontal acceleration, velocity and displacement response of measuring points, that of ordinary Reinforced Concrete(RC) lining is bigger than that of SFRC lining, and the minimum appears in free-field condition; When bedrock vertical vibrating, as to vertical response, that of RC lining is bigger than that of SFRC lining, and the maximum appears in free-field condition.(2) The bendii^ moment and axial force in RC lining section is much bigger than that of SFRC lining, has nothing to do with the vibration direction and the section size of tunnel.