Abstract:
Strong earthquakes can cause fractures and damage to rock masses, leading to the occurrence of geological hazards. Earthquakes, being unpredictable, coupled with the inherent discontinuity and complexity of rock masses, result in insufficient quantitative studies on coseismic rock mass damage. Particularly, there is a lack of comparison of actual damage characteristics before and after earthquakes. Therefore, this article takes the Luding
MS6.8 earthquake in 2022 as an example and conducts qualitative and quantitative research on its damage to rock masses. The adopted methods and main findings are as follows: (1)According to differences in the type and grade of damage, the research area is separated into high and low damage zones. The forms of damage manifest as macroscopic ruptures and fissures strongly opened or regenerated in the high damage zone, while collapses and tension cracks in the rear of the rock mass are discovered in the low damage zone. (2)The degree of rock mass damage can reach an extreme value near the seismogenic fault. The linear density of structural planes increased by 3.44% relative to pre-earthquake levels, and the numerical density of structural planes increased by an average of 6.46%. Additionally, this research introduced an indicator to correct the surveyed damage degree. (3)By using the analytic hierarchy process method, this research established a coseismic rock mass damage evaluation and prediction model. The model considered eight influencing factors, including lithology, epicentral distance, Geological Strength Index(
GSI), slope structure, distance from fault, shear wave velocity(
VS30), peak ground acceleration(
PGA), and peak seismic velocity(
PGV). The results show that the assessment is similar to the actual coseismic damage degree. Hence, this study can provide new scientific evidence for understanding the formation mechanism of seismic secondary disasters.