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Different types of hazards are associated with excavation of soil. for instance, failure of soils at sides of trenches and pits, movement of buildings due excavations at its vicinity, falling workers into pits, buried workers due to collapse of earth, cave-in which may cause suffocations of labors and etc. These hazards should be identified and preventive measures should be taken to avoid any accident at construction sites.

Excavation Hazards- Affects and Prevention Measures

1. Pit Excavation up to 3m

Pits up to three meters may be excavated for testing subsurface soil, monitoring water table, foundation construction etc. There are number of hazards which may be encountered in excavations of pits up to 3m depths. These hazards, their effects, and preventions measures are summarized in Table 1.

Table 1 types of hazards related to pit excavation with a depth of up to 3m plus their influences and prevention measures

Type of hazard Effects of hazard Preventive measures
Falling into pit Personal injury Provide guard rails / barricade with warning signal, provide minimum two entries / exits, Install escape ladders
Earth collapse Suffocation /breathlessness, Buried Employ suitable size of shoring and strutting if required, keep soil heaps away from the edge equivalent to 1.5m or depth of pit whichever is greater. Do not allow vehicles to operate too close to excavated areas. Maintain at least 2m distance from the edge of cut. Maintain sufficient angle of repose. Provide slope not less than 1:1 and suitable depth of excavation in all soils except hard rock. Battering / benching sides.
Contact with buried electric cable, Gas / Oil Pipelines Electrocution, and Explosion Obtain permission from competent authorities prior to excavation if needed. Locate the position of buried utilities Start digging manually to locate the exact position of buried utilities and thereafter use mechanical means.
Excavation of Pits up to 3m
Fig. 1: Excavation of Pits up to 3m

2. Pit Excavation Beyond 3m

This type of pit with such depth might be employed for the construction of foundations of multi-storey buildings in which basements and located, it may also be employed for other applications as well. Hazards associated with pits deeper than 3m meters along with their influences and prevention strategies are presented in Table 2.

Table 2 hazards related to excavation of pits deeper than 3m, their effects and prevention strategies

Type of hazard Effects of hazard Preventive measures
Hazards related to pits up to 3m plus flooding due to excessive rain / underground water cause drowning situation Prevent ingress of water, Identify and provide suitable size dewatering pump or well point system
Digging in the vicinity of existing building / structure Building / structure may collapse, Loss of health and wealth Obtain prior approval of excavation method from local authorities. Use under-pinning method. Construct retaining wall side by side.
Movement of vehicles / equipment close to the edge of cut. cause cave-in or slides, workers may get buried. Barricade the excavated area with proper lighting arrangements. Maintain atleast 2m distance from edge of cut and use stop blocks to prevent over-run. Strengthen shoring and strutting
Pit Excavations
Fig. 2: Pit Excavations
Sliding Failure of Excavations
Fig. 3: Sliding Failure of Excavations

3. Narrow and Deep Excavations

This particular type of excavation is commonly used for pipelines and it may be use for other applications as well. Table 3 provides different hazards, effects, and prevention measures related to narrow and deep excavations.

Table 3 hazards related to narrow and deep excavations along with their influences and preventive measures

Type of hazard Effects of hazard Preventive measures
Pits related hazards plus frequent cave-in or slides Cause severe injuries or prove fatal. Battering / benching of sides. Provide escape ladders.
Flooding due to hydro-static testing Arise drowning situation Battering / benching of sides. Provide escape ladders. Bail out accumulated water. Maintain adequate ventilation.
Narrow and Deep Excavations
Fig. 4: Narrow and Deep Excavations

4. Rock Excavation by Blasting

Hazards and risks caused by rock excavation by blasting is presented in Table 4.

Table 4 hazards associated with rock excavation by blasting and their influences plus preventive measures

Type of hazard Effects of hazard Preventive measures
Improper handling of explosives May prove fatal Ensure proper storage, handling and carrying of explosives by trained personnel. Comply with the applicable explosive acts and rules.
Uncontrolled explosion Can cause severe injuries or prove fatal. Allow only authorized persons to perform blasting operations. Smoking and open flames are to be strictly prohibited.
Scattering of stone pieces to atmosphere Can hurt people Use PPEs like goggles, face mask, helmets etc.
Entrapping of persons / animals May cause severe injuries or prove fatal Barricade the area with red flags and blow siren before blasting.
Misfire May explode suddenly Do not return to site for at least 20min or unless announced safe by designated person.

5. Excavations and Pile Works

Hazards that may be caused by excavations and installations of pile are provided in Table 5.

Table 5 hazards due to excavations and installation of piles

Type of hazard Effects of hazard Preventive measures
Failure of pile-driving equipment Can hurt people Inspect piling rigs and pulley blocks before the beginning of each shift/
Noise pollution Can cause deafness and psychological imbalance. Use personal protective equipment like ear plugs, muffs etc.
Extruding rods/casing Can hurt people Barricade the area and install sign boards Provide first aid
Working in the vicinity of live-electricity Can cause electrocution / asphyxiation Keep sufficient distance from live electricity as per relevant standard codes. Shut off the supply if possible. Provide artificial / rescue breathing to the injured.

About Madeh Izat HamakareemVerified

Madeh is a Structural Engineer who works as Assistant Lecturer in Koya University. He is the author, editor and partner at theconstructor.org.