Objective Regarding the widespread issues of deformation, failure, and stability during reinforcement of rock slopes under excavation disturbance along the Leshan−Xichang Expressway, this study takes the left bedding rock slope at section ZK9+610~ZK9+755 as the research object. It analyzes the potential deformation and failure mechanisms and the stability during dynamic construction, providing support for the optimization of slope support schemes and construction management.

Methods Through field geological surveys and geotechnical physical−mechanical data, a three−dimensional numerical model of a bedding rock slope was established using FLAC3D software. The Mohr−Coulomb elastoplastic criterion was adopted to simulate several typical working conditions, including excavation without support, excavation without support under rainstorm conditions, step−by−step excavation with support, and post−excavation support under rainstorm conditions. The reliability of the model was verified by combining with on−site GNSS surface displacement monitoring data.

Results The results show that local small−scale instability failure occurs in the middle of the slope under the multi−step excavation without support, and large−scale instability failure will occur under the excavation without support and heavy rainfall condition when the distribution range of slope deformation and the value of deformation increase rapidly; The potential deformation and failure mechanism of slope is a sliding tensile fracture mode in which the rock and soil mass on the surface of the slope are subjected to multiple influences such as human engineering disturbance, rainfall, gravity, and the lower muddy weak surface, and are pulled by the leading edge unloading force, sliding along the muddy weak layer in the sandy mudstone; During the slope excavation and support process and under the rainstorm working condition after the completion of the support structure, the displacement of the whole slope and the support structure is small, the safety coefficient is always about 1.2, and the stability is good.

Conclusions The research reveals the failure modes of bedding rock slopes along expressways, which can provide references for predicting similar disasters in analogous slopes. The support system combining anchor cable frame beams and anti−slide pile−sheet walls effectively ensures slope stability during construction and under rainstorm conditions. The findings offer important guidance for the dynamic construction and protective design of similar slopes in the Leshan−Xichang Expressway and the western Sichuan plateau transition zone