Characteristics of in-situ stresses and engineering stability analysis on the south section of the Bohai Strait Cross-Sea Corridor project

Objective The Bohai Strait Cross-Sea Corridor is an important maritime traffic project which joins the Liaodong and the Shandong peninsulas. The state of geostress is an important reference for engineering design and construction decision-making. Method In order to better understand the present characteristics of the geostress and the distribution of the tectonic stress field in the southern section of the project, hydraulic fracturing tests were conducted for stress measurements at 0～300 m depth at Beigou Town, southwest Penglai District, Yantai City. Results The analysis of the measured data indicates that the in-situ stress field is controlled by horizontal tectonic stress in the study area, and the horizontal stress values are at an intermediate level compared with those obtained elsewhere in the Northeast−North China Stress Zone; SH (the maximum horizontal principal stress), Sh (the minimum horizontal principal stress), and Sv (the vertical principal stress) change linearly with the depth of the BGZ borehole; in the depth range of the measurements, the shallow surface stress of the crust is mainly reverse fault type, that is, the relationship of the three principal stresses is SH>Sh>Sv. The measured SH average azimuth angle in the borehole, N75.3°E, is in good agreement with the direction of the tectonic stress field of the North China Stress Zone to which the study area belongs; and, it is basically consistent with the direction of the regional tectonic stress field revealed by the focal source mechanism solution and GPS measurement. The Coulomb friction sliding criterion and the measured data are used to preliminarily evaluate the current level of geostress accumulation in the study area and its impact on the engineering stability. It is believed that the overall level of stress accumulation in the region is relatively low, and the crust in the engineering area is currently relatively stable. In addition, based on the comprehensive discrimination criterion of rock burst danger, \begin{document}$\sigma_{{\text{θ}}_{\max}} $\end{document}/Rc, the possibility of rock burst in the underground tunnel of the Bohai Strait Cross-Sea Corridor is discussed. Conclusion It is primarily concluded that there is currently no possibility of rock burst in the underground tunnel of the Bohai Strait Cross-Sea Corridor, and the rock surrounding the tunnel is stable. Significance The findings in this paper provide a scientific basis for the optimization of the design and the construction of the Bohai Strait Cross-Sea Corridor. The study also provides basic data for research on active faults, seismogeology, regional dynamics in the survey area, and others.