Analytical model of frost heave force evolution in fractured rock mass and analysis of subcritical crack propagation
The frost heave force is an important cause of rock mass failure in the cold region.The traditional analytical model cannot calculate the frost heave force after crack propagation.Considering the influence of crack propagation,it is of great significance to establish an analytical model of frost heave force in fractured rock mass.In this paper,an analytical model of frost heave force evolution in fractured rock mass is derived based on the theory of elastic mechanics,complex variable function and elastic-plastic fracture mechanics.The effects of crack size,freezing rate,water mobility and other factors on the evolution of frost heave force before fracture instability were analyzed.Combined with the estimation of frost heave force after fracture instability,the evolution mechanism and the whole process characteristics of frost heave force were studied.The analytical calculation results were compared with the experimental results.The results show that:(1)The analytical model of frost heave force proposed in this paper can calculate the frost heave force after crack propagation,rationally explain the mechanism of frost heave force fluctuation,and provide a basis for the evaluation of frost resistance of cracks to a certain extent.(2)Before fracture instability,the maximum frost heave force decreases with the increase of fracture length,and the time required to reach the maximum frost heave force increases with the increase of crack width.The maximum frost heave force may decrease with the increase of freezing rate.With the increase of water mobility,the maximum frost heaving force before fracture instability increases,and the time required to reach the maximum frost heave force also increases.(3)The variation of frost heave force can be caused by subcritical crack propagation and instability fracture,and the evolution of frost heave force in cracks is characterized by fluctuation.When there is no instability fracture in the freezing process,the frost heave force fluctuates and increases.When there is instability fracture in the freezing process,the frost heave force first increases and then decreases.
rock mechanicsfractured rock massfrost heaving forceanalytical modelsubcritical propagationfluctuation change
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