Thermal spallation drilling [1] is a new technology that aims to increase the drilling efficiency. This new strategy has implications in the nonlinear coupled axial-torsional vibrations of the drill string [2]. In this paper, a 2-DOF model that considers axial and torsional dynamics is analyzed. For the first time, the effects of thermal spallation, which decreases the rock resistance, is considered in the nonlinear bit-rock interaction that couples axial and torsional vibrations. The cutting parameter is modeled as a random process, that is, perturbations are considered over time. The system of random ordinary nonlinear differential equations is analyzed for different operational scenarios. A stochastic map shows the increase of the safe zone’s size when thermal spallation is active. REFERENCES [1] E. Rossi, S. Jamali, M.O. Saar, M.O. and P. Rudolf von Rohr. Field test of a Com- bined Thermo-Mechanical Drilling technology. ModeI: Thermal spallation drilling. Journal of Petroleum Science and Engineering, Vol. 190, 107005, 2020. [2] D.M. Lobo, T.G. Ritto, D.A. Castello, M.L.M. Souza. On the calibration of drill- string models based on hysteresis cycles data. International Journal of Mechanical Sciences, Vol. 177, 105578, 2020