In excavation & trenching, hydraulic shoring is a prefabricated strut and/or wale system manufactured of aluminum or steel. Hydraulic shoring provides a critical safety advantage over timber shoring because workers do not have to enter the trench to install or remove hydraulic shoring. Other advantages of most hydraulic systems are that they: All shoring should […]
What is a Plasticity or Wet Thread Test?
In excavation & trenching, a plasticity or wet thread test is conducted by molding a moist sample of the soil into a ball and attempting to roll it into a thin thread approximately 1/8 inch (3 mm) in diameter (thick) by 2 inches (50 mm) in length. The soil sample is held by one end. […]
What is Unit Weight of Soil?
The Unit Weight of Soil refers to the weight of one unit of a particular soil. The weight of soil varies with type and moisture content. One cubic foot of soil can weigh from 110 pounds to 140 pounds or more, and one cubic meter (35.3 cubic feet) of soil can weigh more than 3,000 […]
What is Toppling in Excavation & Trenching?
In addition to sliding, tension cracks can cause toppling. Toppling occurs when the trench’s vertical face shears along the tension crack line and topples into the excavation. For additional information, see OSHA Technical Manual (OTM) Section III: Overview: Soil Mechanics. At Ron Meyer & Associate Excavating, Inc, we’ve been providing underground and commercial construction to private […]
Subsidence and Bulging in Excavation & Trenching
An unsupported excavation can create an unbalanced stress in the soil, which, in turn, causes subsidence at the surface and bulging of the vertical face of the trench. If uncorrected, this condition can cause face failure and entrapment of workers in the trench. For additional information, see OSHA Technical Manual (OTM) Section III: Overview: Soil Mechanics. […]
Testing the Unconfined Compressive Strength of Soil with a Shearvane (Torvane)
To determine the unconfined compressive strength of the soil with a shearvane, the blades of the vane are pressed into a level section of undisturbed soil, and the torsional knob is slowly turned until soil failure occurs. The direct instrument reading must be multiplied by 2 to provide results in tons per square foot (tsf) […]
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