Slope Stability Evaluation Processes

Attention geotechnical and structural engineers looking at slope stabilization: When excavating a roadway on an existing slope, it is essential to consider both undrained and drained conditions if clays are encountered. Clays on a slope are often an indication of past instability. Here are a few things that can you do: a) Get good quality geotechnical data beyond SPT values b) Examine complex slope stability surfaces c) Sometimes, the most critical slope stability might not be in the normal direction of your shoring. Look for the most critical slope that might not be normal to the shoring. d) Run both LEM slope stability and c-PHI strength reductions e) Check your wall forces with both LEM and FEM f) Establish a proper instrumentation program In this real-life case, a slope experienced many of these issues. The undrained slope stability safety factor was very small, which led to much larger displacements. In DeepEX, everything that is required is in one place; no need to use different packages to get all answers. Follow Deep Excavation LLC for more tips!

Rock Bridging in Slope Stability Analysis:   Rock bridging occurs when failure propagates partly through joints and partly through intact rock, with the intact rock bridges resisting movement and enhancing stability. This interaction between joints and rock bridges significantly influences slope behavior and the evaluated factor of safety.   RS2, with FEM, Joints Network capabilities, and Shear Strength Reduction (SSR), is ideal for modeling problems of any complexity, including complex geology and discrete fracture networks (DFNs). It efficiently captures stress redistribution and failure mechanisms involving both joints and intact rock.   Slide2, using LEM, can address rock bridging by incorporating Weak Layer entities. The “Particle Swarm Search” combined with “Heuristic Weak Layer Handling” is an efficient method for this problem. However, the complexity of problems it can handle is limited compared to RS2's capabilities.   The choice between RS2 and Slide2 depends on the complexity of the slope and the required level of simulation precision.    Rocscience #GeotechnicalEngineering #Mining #MiningEngineering #SlopeStability #FiniteElementAnalysis #LimitEquilibrium

A student asked me to help him understand the Shear Strength Reduction (SSR) in Slope Stability Analysis. You may also find this helpful. The shear strength reduction (SSR) method is a numerical method used to assess slope stability. It calculates the Factor of Safety (FS) by systematically reducing the soil or rock shear strength parameters by a factor called the Strength Reduction Factor (SRF) until slope failure occurs. The reduced shear strength parameters are used in the numerical model to assess slope stability. The software runs the model and checks for convergence. The process is repeated, iterating the SRF each time, until the slope fails (the model can no longer achieve equilibrium, or the numerical solution diverges). The value of SRF at this point is interpreted as the slope’s factor of safety. Unlike LEM, SSR (FEM) provides information not just on stability (FoS) but also on deformations, strains, and progressive failure mechanisms. ▶️ Illustration To illustrate this, I used Slide2 (Limit Equilibrium Method—LEM) and RS2 (Finite Element Method—FEM) to analyse the stability of slopes in weak rock masses with an overall slope angle of 37°. The slope stability was first analyzed using Slide2 (Figure 1), employing conventional LEM techniques. The model was then imported into RS2 (Figure 2), where the Shear Strength Reduction (SSR) method was applied to assess the same slope’s stability under FEM. ▶️Results 1. Both Slide2 and RS2 (FEM) yielded a factor of safety of 1.07 (Figures 3 & 4) 2. The maximum shear strain zone obtained from RS2 closely matched the slip surface predicted by Slide2 (Figure 4). 3. Unlike Slide2, RS2 was also able to show the displacement and deformation at critical factor of safety (Figure 6). #RS2 #Slide2 #GeotechnicalEngineering #SlopeStability #ShearStrengthReduction #NumericalModelling #FiniteElementMethod #RockMechanics #SoilMechanics #EngineeringGeology #FEMvsLEM #Geomechanics #SlopeDesign #MiningEngineering #CivilEngineering I will be sharing similar posts tailored for students, so stay tuned.