Three-dimensional geological modelling and long-term stability analysis of high-steep dangerous rock masses based on multisource data integration

Abstract

Extensive high, steep and perilous rocky slopes are present on both sides of the Three Gorges Reservoir area, with numerous such slopes interspersed. The rock mass structure of this type of dangerous rock slope is complex, strongly affecting the stability of the rock masses in this region. Hence, it is necessary to establish a detailed 3D geological model in combination with the internal structural characteristics of the rock mass. Taking the Jianchuandong 3# dangerous rock mass (JDRM 3#) in the Three Gorges Reservoir area as an example, this study integrated UAV photogrammetry technology and 3D laser scanning technology to establish models of the surface of the dangerous rock mass, internal dissolution cavities and random fissures. A 3D geological model of JDRM 3# was constructed by integrating these models. Based on the constructed model, the evolution process of the deformation of JDRM 3# under the influence of long-term water-level fluctuation was simulated. The simulation results showed that long-term water-level fluctuation can lead to a deterioration in the strength of the base of the rock mass, with deformation and failure of the dangerous rock mass initially occurring around the internal dissolution cavities. A change in the internal structure of the rock mass played a vital role in the failure process of JDRM 3#, which aggravated the eccentric compression state of the base of the rock mass. It will eventually lead to a collapse failure of JDRM 3#. When the compressive strength of the base of the rock mass decreased by approximately 70.3%, the factor of safety (FOS) for JDRM 3# was <1. By combining different geological investigation methods to establish a 3D geological model and using it for numerical calculations, this study provides a novel method to assess the stability of high-steep bank slopes in reservoir areas.