A new method for assessing excavation damaged zone based on point safety factor.

Excavation of a rock slope will form an excavation disturbance/damage zone (EDZ) near the excavation boundary. This paper proposes an EDZ analysis method based on point safety factor. The ratio of the shear stress to shear strength of each point in the slope is defined as the point safety factor, and the expression of the point safety factor under the Mohr–Coulomb and Hoek–Brown criteria is derived. The point safety factor before and after the excavation of a highway rock slope is calculated, and the influence of the Hoek–Brown parameters on the point safety factor is studied. The change rate of the point safety factor before and after slope excavation is used as a quantitative index to study the scope of EDZ, and the influence of excavation angle on EDZ is discussed. The results show that the point safety factor first increases and then decreases from the slope surface to the slope interior. After the slope is excavated, the point safety factor at the toe of the excavation face is significantly reduced, and its change is related to the stress adjustment of the rock mass in the slope. The point safety factor increases with the increase of the geological strength index GSI and uniaxial compressive strength σci of the rock mass, and decreases with the increase of the material constant m_i and the disturbance factor D. As the excavation angle increases, the range of EDZ becomes smaller. The maximum point safety factor change rate occurs on the excavation boundary with a height of 1.8 ~ 2.0 m, which first increases and then decreases with the increase of the excavation angle. [ABSTRACT FROM AUTHOR]