Resisting and Driving Forces

Slope stability depends on the balance between resisting forces (from soil shear strength) and driving forces (gravity forces). Changes in these forces can disrupt equilibrium and cause slope failure. Driving forces increase due to geometry changes, seepage pressure, additional loads, and more. Resisting forces decrease when pore water pressure rises from soil saturation.

Factors influencing soil resisting forces include:

  • Soil type: Cohesive granular soils provide the highest shear strength, making excavation easier.

  • Soil moisture content: Higher moisture reduces shear strength and resisting forces, increasing instability risk.

  • Groundwater origin and level: Poor groundwater control and drainage can cause irregular settlements due to soil liquefaction.

  • Slope height and angle: Greater height and steeper slopes raise driving forces, necessitating stronger stabilization methods.

For proper retaining structure design, consider:

  • Design approach, safety factors, service life, and project importance.

  • Temporary vs. permanent stabilization: Temporary focuses on short-term stability during construction, while permanent requires higher safety factors and seismic considerations.

  • Monitoring slope displacement and safety factors against sliding based on project importance and adjacent structures.

  • Site constraints such as allowable displacement, neighboring excavation permits, and available working space affect system choice.

  • Time and cost management to select the safest, most economical, and timely stabilization method.