Stability evaluation and potential failure process of rock slopes characterized by non-persistent fractures

Slope failure, which causes destructive damage and fatalities, is extremely common in mountainous areas. Therefore, the stability and potential failure of slopes must be analysed accurately. For most fractured rock slopes, the complexity and random distribution of structural fractures make the aforementioned analyses considerably challenging for engineers and geologists worldwide. This study aims to solve this problem by proposing a comprehensive approach that combines the discrete fracture network (DFN) modelling technique, the synthetic rock mass (SRM) approach, and statistical analysis. Specifically, a real fractured rock slope in Laohuding Quarry in Jixian County, China, is studied to show this comprehensive approach. DFN simulation is performed to generate non-persistent fractures in the cross section of the slope. Subsequently, the SRM approach is applied to simulate the slope model using 2D particle flow code software (PFC2D). A stability analysis is carried out based on the improved gravity increase method, emphasizing the effect of stress concentration throughout the formation of the critical slip surface. The collapse, rotation, and fragmentation of blocks and the accumulation distances are evaluated in the potential failure process of the rock slope. A total of 100 slope models generated with different DFN models are used to repeat the aforementioned analyses as a result of a high degree of variability in DFN simulation. The critical slip surface, factor of safety, and accumulation distance are selected by statistical analysis for safety assurance in slope analysis and support.

Stability evaluation and potential failure process of rock slopes characterized by non-persistent fractures

Slope failure, which causes destructive damage and fatalities, is extremely common in mountainous areas. Therefore, the stability and potential failure of slopes must be analyzed accurately. For most fractured rock slopes, the complexity and random distribution of structural fractures make the aforementioned analyses considerably challenging for engineers and geologists worldwide. This study aims to solve this problem by proposing a comprehensive approach that combines the discrete fracture network (DFN) modeling technique, synthetic rock mass (SRM) approach, and statistical analysis. Specifically, a real fractured rock slope in Laohuding Quarry in Jixian County is studied to show this comprehensive approach. DFN simulation is performed to generate non-persistent fractures in the cross section of the slope. Subsequently, SRM approach is applied to simulate the slope model using 2D particle flow code software (PFC2D). A stability analysis is carried out based on the improved gravity increase method, emphasizing the effect of stress concentration throughout the formation of the critical slip surface. The collapse, rotation, and fragmentation of blocks and the accumulation distances are evaluated in the potential failure process of the rock slope. 100 slope models generated with different DFN models are used to repeat the aforementioned analyses as the result of a high degree of variability in DFN simulation. The critical slip surface, factor of safety, and accumulation distance are selected by statistical analysis for safety assurance in slope analysis and support.

Stability analysis of strain-softening slopes based on the gravity increase method

With traditional slope stability analysis methods, it is difficult to accurately describe the progressive failure process and dynamic variation law of slope stability. The strain-softening constitutive model was therefore used to simulate the progressive failure process of a strain-softening slope based on the gravity increase method (GIM), with the displacement interface employed to determine the sliding surface. A sensitive analysis of the characteristic parameters within the softening stage was then conducted. The results are as follows: There are similar space-time evolution laws of residual strength factor and shear strain increment, with failure starting from the slope toe and extending gradually. The sliding surface of strain-softening slopes is located between that of the slope with peak strength and the sliding surface of the slope with residual strength. The stability coefficient shows an exponential growth trend with the increase of residual cohesion and residual plastic shear strain threshold, with a positive linear correlation between the residual friction angle and stability factor. The residual friction angle is the most sensitive factor in slope stability, followed by the residualcohesion, with the residual plastic shear strain threshold being the least sensitive.

On the Application of Finite Element Method (FEM) to the Slope Stability Analyses

The finite element method (FEM) is widely adopted in the geotechnical engineering, but there exist some problems in practical applications, such as the lack of unified standard to determine parameters and the limitation of the calculation method. This article determines the reasonable value of Poisson ratio, by comparing different Poisson ratios selected in the strength reduction of FEM calculations, and improves the gravity increase method in order to enhance its accuracy in the gentle slope stability analyses.