Abstract:
In order to study the dynamic and static shear properties of the freeze-thaw deteriorated concrete, the compressive-shear strength tests on concrete are carried out under different normal stresses (0, 3, 6, 9 and 12 MPa) after different freeze-thaw cycles (0, 10, 25, 35 and 50 times), and the concrete strength grade is C30. The impacts of the freeze-thaw cycles and normal stress on the shear strength, peak strain, cohesion and friction coefficients of concrete are studied. The analysis results show that:① With the increase of the freeze-thaw cycles, the shear strength of concrete decreases gradually under the same normal stress status. The greater the normal stress is, the smaller the shear strength of concrete decrease degree with the increase of the freeze-thaw cycles. When the number of the freeze-thaw cycles is the same and the normal stress is less than 50%of the uniaxial compressive strength, the shear strength increases with the increase of the normal stress, and the deterioration of freezing and thawing will affect the results of this increase. ② When the normal stress is the same, the shear peak deformation increases linearly with the increase of the freeze-thaw cycles. For a certain freeze-thaw cycle, the existence of the normal stress increases the shear peak deformation of concrete. ③ The coefficients of friction and cohesion decrease with the deepening of the deterioration degree of freeze-thaw, and the significant decrease of cohesion is due to the dominant role of freezing and thawing deterioration. ④ On the basis of the above experimental analysis and the compression-shear failure criterion of octahedron stress space in the form of quadratic parabola, a compression-shear failure criterion of concrete considering the number of freeze-thaw cycles in plane stress state is established.