Slope engineering geology characteristics and stability evaluation of a grand bridge to Chengdu bank on the Sichuan-Tibet Railway

The planned grand bridge is an important control bridge along the Sichuan-Tibet Railway. A large- scale bedding rock collapse occurred on the slope of the Baqu river side of Chengdu bank, with the protruding ridge, high elevation difference, complex and changeable lithology, poor rock mass structure and integrity, highly weathering and unloading and potential unstable rock mass on the surface of the slope. This paper investigates the topography and geomorphology, stratum lithology, discontinuities development and the characteristics of deformation and failure of the bank slope to Chengdu by remote sensing interpretation, profile measurement and stability calculation. The stability of bedding rock slope of the Baqu river side of Chengdu bank under natural and rainstorm conditions are analyzed and evaluated. The results show that the safety factor of slope stability is greater than 1.1; under the strong earthquake (PGA>0.3 g) conditions, the safety factor of slope stability is less than 1.0, and local or overall instability may occur. Based on removing the dangerous rock mass on the surface of the slope, it is suggested that the possible failure range and degree of the bedding rock slope on the Baqu river side should be further studied and the engineering prevention measures should be put forward.