Elasto-plastic solution for frost heave force considering Hoek-Brown criterion and freezing temperature gradient in cold region tunnels

Abstract

The tunnel frost heave force is a primary cause of frost damage in cold region tunnels. To guide the prevention and treatment of tunnel frost damage, an elastic–plastic solution for the frost heave force is proposed based on the nonlinear Hoek-Brown (H-B) strength criterion. The elastic–plastic calculation model for the frost heave force simultaneously considers the variation of the volumetric frost heave strain of the surrounding rock with the freezing temperature and the uneven frost heave linear strain. The elastic–plastic analysis of the tunnel frost heave force and development of plastic damage in rock masses based on the H-B criterion is performed through engineering examples in cold regions. The frost heave force of Dabanshan Tunnel obtained by the H-B criterion elastic–plastic solution is 1.14 MPa, which is basically consistent with the monitoring values. The plastic radius is 5.72 m. But the calculation using the linear strength criterion results in a smaller frost heave force and a larger plastic zone radius. And the corresponding parameters of the H-B criterion directly use the rock mass parameters in the survey report, which is convenient for engineering application. The parameter analysis reveals that the plastic zone and frost heave force gradually increase with decreasing GSI and increasing disturbance parameter D. The degree of disturbance has a significant effect on the frost heave force and the plastic zone radius, and is an influencing factor that cannot be ignored.