Why Soil Types Matter When Using Shoring

All construction operations carry inherent risks, but excavations are widely recognized as being among the most dangerous. Cave-ins and trench collapses pose a grave threat to worker safety, as they cause fatalities and injuries every year. The erection of the proper shoring keeps workers safe. Engineers must assess the type of soil in the area before they can determine the proper method for building shoring.

Identifying Stable Rock

The Occupational Safety and Health Administration (OSHA) recognizes four categories of soil and rock deposits. The first is stable rock, such as granite or sandstone. Solid rock can be safely excavated with vertical sides, as it will remain intact. However, before classifying a deposit as solid rock, the engineer must determine whether the rock contains cracks.

Identifying Type A Soil

Type A soils are typically clay, clay loam, and silty clay. These are cohesive soils that feature an unconfined compressive strength of 1.5 tons per square foot or greater. Note that no soil may be classified as type A if any of the following are applicable:

  • It’s part of a sloped, layered system
  • It’s been previously disturbed
  • It’s fissured
  • It’s been subjected to vibrations
  • It has seeping water

Identifying Type B Soil

Type B soils are also cohesive soils. Typical examples include angular gravel, silt loam, silt, and dry, unstable rock. Type B soils have an unconfined compressive strength between 0.5 and 1.5 tons per square foot. It’s also possible for a soil to be classified as type B if it’s been subjected to vibrations or fissures, but would otherwise be classified as type A soil.

Identifying Type C Soil

Some examples of type C soils are gravel, sand, submerged soil, loamy sand, soil with seeping water, and unstable, submerged rock. On construction sites, it’s most common for deposits to be classified as type C. These cohesive soils have an unconfined compressive strength of less than 0.5 tons per square foot.

If your company is planning excavation work, you can count on the expertly trained team at Scaffold Resource to provide safe, compliant shoring erection services. Call us at (301) 924-7223. We also offer scaffolding rentals near Washington, D.C.

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