🕑 Reading time: 1 minuteExcavation support or earth retaining structures are required where excavation is deep and required slope cannot be provided. Types of excavation supports are discussed.
What Are Excavation Supports?In general, to construct a structure either above the ground or below the ground, excavation of soil is necessary in the ground. The excavation may be shallow or deep based on our requirement. But when deep cuts are made in soil, the soil from the sides of excavated area may collapse due to low stability. To prevent this and to make the cut accurate vertical we need some temporary earth retaining structures called excavation supports. The failure of soil cut arises when the limit of excavation exceeds its safe height limit and it depends upon unconfined compressive strength of soil and cohesion. Following table provides the safe height limit for different soil types based on their unconfined compressive strength and cohesion limits.
|Soil type||Unconfined compressive strength (psf)||Cohesion (psf)||Safe height (ft)|
|Very soft||Less than 500||<250||<5|
Types of Excavation SupportsGenerally, there are two most commonly adopted methods of providing excavation supports:
- Soldier pile and lagging
- Soil nailing