Stratigraphic uncertainty is widely present in nature, but it has not been well considered in the stability analysis of unsaturated soil slopes in the past. In this study, the stability of the unsaturated soil slope is evaluated based on borehole data considering stratigraphic uncertainty. Firstly, an enhanced coupled Markov chain model is used to simulate stratigraphic uncertainty. Then, a finite element algorithm for automatically calculating the safety factor (FS) and the average groundwater table (AGT) of the unsaturated soil slope is developed. At last, a hypothetical slope located in the stratum from Perth, West Australia is analyzed using the proposed algorithm under different borehole schemes. The results show that with the increase in the borehole number, the statistics of FS and AGT will not monotonically increase or decrease. But the trend is that the mean values of FS and AGT gradually approach and eventually converge to the real values, and the standard deviations of FS and AGT decrease. There is a linear relationship between the standard deviation of FS (or AGT) and the average information entropy. The FS and AGT are negatively correlated considering stratigraphic uncertainty.

On the basis of systematically sorting out the potential risk sources of underground structure construction, this paper describes the surrounding medium of underground structure as soil mass and rock mass. The main risk source of the underground structure based on soil medium comes from the construction mechanics analysis in the construction stage, and the leading factor of the underground structure loading in the construction stage is the stress-strain relationship of soil based on the unloading path. The deep underground engineering structure is faced with a series of disasters such as high-strength water escape, high-strength rock burst, large deformation of soft rock, boulder collapse and rock burst under the action of unloading. In view of the unloading paths faced by the above two different media, the corresponding physical models are developed to describe the above phenomena according to their respective disaster evolution mechanism and disaster breeding mechanism, and the corresponding indexes required for the safety of engineering structures are obtained by solving the physical equations. According to the above indicators, the engineering structure and surrounding media in the construction process are monitored accordingly, and the feedback of the monitoring data is used to obtain the risk assessment and modify the current construction sequence, so as to provide a reference for better serving the construction safety of underground engineering structures.