Safety in Excavations : Safety in Excavations A guided study of understanding the risks and dangers in excavation work


Topics to be Discussed : Topics to be Discussed Soil Types Shear Strength Collapse Types Strength Factors Protective Measures


Safety in Excavations: Safety in Excavations In General: An employer is required to provide safe means of access to and egress from a work area above or below ground level by means of stair, ladder, runway or ramp. The access way must be well maintained well-lit, clear of obstructions, and be suitable abrasive to ensure firm footing for workers.


Safety in Excavations: Safety in Excavations Excavation work cannot commence until the Labour Division has been notified and the employer has received a registration number and has notified public utilities. If the employer does not perform the excavation in accordance with the Construction Industry Safety Regulation of the Workplace Safety and Health Act, the registration may be revoked and the excavation shut down.


Safety in Excavations : Safety in Excavations Soil Types


Soil Types: Soil Types Stable Rock Type A Soil Type B Soil Type C Soil Layered Geological Strata


Safety in Excavations : Safety in Excavations Shear Strength


Shear Strength: Shear Strength “ The capacity of a material to resist the internal and external forces which slide past each other “


Shear Strength: Shear Strength Cohesion The stickiness of the soil; a greater amount of clay than sand. Internal Friction A result of particle shape.


Safety in Excavations : Safety in Excavations Strength Factors


Strength Factors: Strength Factors Water Vibrations Erosion and Weathering Excavation Depth Slope Steepness Degree of Soil Compaction


Safety in Excavations : Safety in Excavations Collapse Types


Collapse Types: Collapse Types Zone of Exposure


Collapse Types: Collapse Types Zone of Exposure Spoil Pile Slide


Collapse Types: Collapse Types Zone of Exposure Spoil Pile Slide Side Wall Shear


Collapse Types: Collapse Types Zone of Exposure Spoil Pile Slide Side Wall Shear Slough – in


Collapse Types: Collapse Types Zone of Exposure Spoil Pile Slide Side Wall Shear Slough – in Rotation


Safety in Excavations : Safety in Excavations Shoring Techniques


Shoring Techniques: Shoring Techniques Engineers are often required to design shoring, which is a construction procedure used specifically to maintain the stability of the walls of an excavation and provide protection to workers who may enter the excavation


Shoring Techniques: Shoring Techniques Accidental Falling Entry Excavation sites cannot be crowed with anything such as piles of excavated material or excavation equipment which might accidentally fall into the excavation. All work areas adjacent to public walkways must be adequately guarded or barricaded by fences, guardrails or a covering sufficient to prevent persons from falling into the excavation.


Shoring Techniques: Shoring Techniques Shafts and Tunnels Due to the specific nature and hazards of the work, a professional engineer may be required to design a support structure for a shaft or tunnel prior to commencement. At least one worker in each work crew must be experienced in the type of work being performed in shaft and tunnel excavations, and at least one worker is required to be trained in first aid.


Shoring Techniques: Shoring Techniques Access Way Employers must surround the opening to an underground excavation with a firm, level area and a protective barrier (at least 1 meter in height) surrounding it. The access way must be secured with a cover to prevent unauthorised entry. Access landings, the bottom of shafts and tunnels, and other similar work areas must be kept free of loose mud and other accumulations of debris.


Shoring Techniques: Shoring Techniques Atmosphere Every employer must provide a suitable ventilation system in a shaft or tunnel excavation to ensure that there is no lack of oxygen and that concentrations of toxins in the atmosphere are minimised. No employer shall allow internal combustion engines to be used in underground work areas unless the engines are properly engineered to do so.


Shoring Techniques: Shoring Techniques Illumination Every employer must provide electrical illumination for the full length of the tunnel and at the face of the excavation where inadequate natural light is present. Where electrical illumination is used in an underground excavation, employers are required to provide an emergency lighting system.


Shoring Techniques: Shoring Techniques First Aid in Shafts and Tunnels Employers must ensure that: At least one worker holding a valid first aid certificate must be present during each shift. A first aid kit is provided in the immediate vicinity of the entrance to a shaft or tunnel. A basket stretcher and blankets are provided at each worksite. Workers are instructed in proper underground rescue procedures.


Shoring Techniques: Shoring Techniques Flammable and Combustible Hazards Flammable and combustible liquids shall not be used underground unless they are stored in accordance with the Manitoba Fire Code. Effective means for extinguishing a fire in an underground excavation must be provided where combustible or flammable materials may be present.


Shoring Techniques: Shoring Techniques Wood Support


Shoring Techniques: Shoring Techniques Wood Support Screw Jacks


Shoring Techniques: Shoring Techniques Wood Support Screw Jacks Hydraulic Shores


Shoring Techniques: Shoring Techniques Wood Support Screw Jacks Hydraulic Shores Spacing


Shoring Techniques: Shoring Techniques Wood Support Screw Jacks Hydraulic Shores Spacing Trench Cages


Concluding Remarks: Concluding Remarks Excavation Work is a highly dangerous industry. Safety standards need to be implemented and stringently maintained