###### Abstract
[PERSON] studied the effect of thermal-mechanical coupling on the movement and damage of gasifier surrounding rock under elastic-plastic models of different coal and found that the linear elastic model with stress rebalancing can predict rock deformation accurately [14]. [PERSON] concluded that the thermal fracture of rock caused by the high temperature is an important reason for surrounding rock instability, and the larger the temperature difference inside the gasifier, the more severe the thermal fracture of rock [21]. [PERSON] studied the deformation damage of overburdened strata under different gasifier sizes and temperature field expansion characteristics and found that the temperature field can change the mobile damage characteristics of rock strata over a wide range [22]. In terms of surface subsidence prediction, various prediction methods have been developed from the continuous medium theory and the random medium theory through long-term research. Some scholars considered rock formations as elastomers and studied the mining subsidence problem from the perspective of elastic mechanics [23; 24]. However, determining the mechanical parameters is difficult due to the complicated geological mining conditions, affecting the popularization and application of continuum theory [25]. The random medium theory regards the transfer of settlement from underground to the surface as a random process and develops the probability integral method of settlement prediction using the statistics principle. However, this method is mainly aimed at mining subsidence prediction under the condition of full roof collapse. Its prediction effect is not ideal when the roof is relatively stable [26; 27]. In the process of UCG, the gasification space must be relatively stable, and extreme conditions such as the large-scale collapse of the gasifier and instability of isolated coal pillar cannot occur. In addition, true mining thickness cannot be used for subsidence prediction, which brings specific difficulties to the prediction of surface subsidence. [PERSON] used the probability integral method to compare the differences between UCG and strip mining and believed that the surface subsidence caused by UCG could be predicted by adjusting the subsidence coefficient [28]. [PERSON] studied the law of surface subsidence caused by UCG through field measurements [29]. Then, [PERSON] studied the law of surface subsidence caused by UCG by setting up a surface subsidence observation station on the surface [30]. However, effective means to predict surface subsidence under UCG conditions are still lacking. There are two main reasons for the stalemate in predicting surface subsidence under UCG and the lack of an effective method to predict surface subsidence under stable roof conditions in thermally coupled conditions. First, how the high-temperature environment affects the surface subsidence law of UCG is uncertain. Second, effective methods for predicting surface subsidence under the condition of a stable roof in thermally coupled conditions are lacking. Based on these two problems, this study takes the Ulanqab UCG experiment in Inner Mongolia as an example. The study initially examines the main controlling factors that change the rock strata movement and surface subsidence characteristics of UCG using the numerical simulation method. Then, a method for predicting the surface subsidence of UCG based on the continuous-discrete medium theory is established. The predicted results are close to the actual monitoring results, and good results are obtained in the case verification. This study can provide an important reference for rock movement control, an important means for assessing the environmental impact, and theoretical and technical support for the industrialization development of UCG.