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EXCAVATION SAFETY
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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OVERALL GOAL
• employees who work in or around excavations
• the general public who work or travel in the vicinity of excavations.
ASSURE THE SAFETY OF:
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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TOPIC OBJECTIVE
• Look back on the principle of soil mechanics in applying excavation safety;
• Analyze case and assess the proper orientation of backhoe during operation;
• Become aware of the OHS requirements on excavation work.
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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INTRODUCTION
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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EXCAVATION SAFETY
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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SOIL MECHANICS
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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DEFINITIONS
SOIL MECHANICSSOIL MECHANICS
In trenching and excavation practices, SOIL is defined as any materials removed from the ground to form a hole, trench or cavity for the purpose of working below the earth’s surface.
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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EXCAVATION - a man-made cavity or depression in the earth’s surface.
OPEN EXCAVATION (Bulk Excavation) - an excavation where the width is equal to or greater than the depth.
TRENCH EXCAVATION - an excavation having a depth which exceeds its width (max. 15 ft. for US, 12 ft. in UK measured at the bottom.
DEFINITIONS
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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SOIL MECHANICS
Overburden PressureOverburden PressureSoil Mechanics point of view:
1 foot 1 foot
500 psf250 psf
250 psf 250 psf
250 psf
100#
100#
100#
100#
100#
1 foot
Figure 1. Forces exerted by a column of
soil.
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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Figure 2. Mechanics of Trench Failure.
(2a) (2b)
TRENCH FAILURESTRENCH FAILURES
(2c) (2d) (2e)
SOIL MECHANICS
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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SOIL MECHANICS
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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SOIL CLASSIFICATIONSOIL CLASSIFICATION• Stable Rock - natural solid mineral matter that
can be excavated with vertical sides and remain intact while exposed.
• Type A - cohesive soil with unconfinedcompressive strength of 144 kPa or
greater. Examples;
clay, silty clay, clay loam, sandy clay, clay loam
and silty clay loam and sandy
clay loam.
SOIL MECHANICS
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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SOIL CLASSIFICATIONSOIL CLASSIFICATION• Type B - cohesive soil with unconfined
compressive strength greater than 48 kPa but less than 144 kPa.
Examples;angular gravel, silt, silt loamsandy loam
• Type C - cohesive soil with unconfinedcompressive strength of 48 kPa or
less. Examples; gravel, sand, loamy sand submerged soil
SOIL MECHANICS
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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TYPES OF SOIL COLLAPSETYPES OF SOIL COLLAPSE
• General zone of exposure (fracture point)The area where workersare exposed to masssoil/rock movement.
• Spoil pile slide Poor excavatingprocedures where thethe excavated material isnot placed far enough awayfrom the edge of the excavation.
SOIL MECHANICS
1/2-3/4 of depth or 1:1
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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TYPES OF SOIL COLLAPSETYPES OF SOIL COLLAPSE
• Side wall Shear Common to clay type soilswhich are exposed to drying.
• Slough-in (Cave-in) Common to previously excavatedmaterial, sand and gravel.
• Rotation Clay-type soils when saturated with water.
SOIL MECHANICS
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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Six Factors for Soil InstabilitySix Factors for Soil Instability
SOIL MECHANICS
• Increase in depth• Saturation• Hydrostatic Pressure (water table)• Weight of excavated soil materials or equipment near excavation• Shock or vibration• Frost faction
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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OSH REQUIREMENTS
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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OSH REQUIREMENTS
GENERAL REQUIREMENTSGENERAL REQUIREMENTS
• TRAIN WORKERS
Employees who work in or around excavations must be provided training according to their work.
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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OSH REQUIREMENTS
GENERAL REQUIREMENTSGENERAL REQUIREMENTS
• PERSONAL PROTECTIVE EQUIPMENT (PPE)
All workers doing excavation work must wear approved safety footwear and safety headgear. Additional PPE is required depending on the risk assessment for the work to be undertaken.
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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OSH REQUIREMENTS
GENERAL REQUIREMENTSGENERAL REQUIREMENTS
• PUBLIC PROTECTION & TRAFFIC CONTROL
Traffic around the site must be controlled, and barricaded, signs and/or flag persons used as needed to control both vehicular and pedestrian traffic.
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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OSH REQUIREMENTS
GENERAL REQUIREMENTSGENERAL REQUIREMENTS• PROTECTION SYSTEMS
The excavation or trench must either be sloped or supported as required to comply with OSHS.
Excavation over 1 m deep: a. protection/support system must
be installed except when:- There are no exposure- Cut in solid rock- With angle of repose- Workers are protected during
installation of shoringb. Kept free of water all the times
ANGLE OF REPOSE
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
Jump to first pageBy: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
Jump to first pageBy: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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Maximum Allowable Slopes
Soil Type Vertical Horizontal Remarks
for excavation less than 20 feet
A
B
C
Stable rock
1
90 deg
1
1 3/4
1/2 <12 feet @ 63 deg*
>12 feet @ 53 deg*
*short-term only
1 45 deg
1 1.5 34 deg
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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OSH REQUIREMENTS
1/3 depth
GENERAL REQUIREMENTSGENERAL REQUIREMENTS• LOCATION OF EXCAVATED
MATERIALS AND EQUIPMENT
Tools and excavated materials must be piled in a manner that it cannot rollback into the excavation. It must never be closer than 1 meter from edge of excavation.
Equipment and heavy machinery shall not be place near the edge of excavation at least 1/3 of its depth.
1/3 depth, 1 m
. min.
1/3 depth, 1 m
. min.
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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Near the edge of excavation?
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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OSH REQUIREMENTS
GENERAL REQUIREMENTSGENERAL REQUIREMENTS
• PROVISION FOR ACCESS/ EGRESS
A suitable means of access/egress (ladders,stairways,etc) must be provided for workers entering an excavation.
A ladder must be located within 25 ft or 8m of a worker’s working position.
d>1 m
0.83 m
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
SAFE ACCESS/EGRESS?
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
A SAFE ACCESS/EGRESS
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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OSH REQUIREMENTS
GENERAL REQUIREMENTSGENERAL REQUIREMENTS
d>2 m
1.0 m
• PROVISION FOR BARRICADES
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
BARRICADES?
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
BARRICADES?
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
ANY HAZARDS?
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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OSH REQUIREMENTS
GENERAL REQUIREMENTSGENERAL REQUIREMENTS
• EXPERIENCED SUPERVISOR
An experienced and trained worker is designated to directly supervise each excavation project.
- sloping and benching- shoring requirements- emergency rescue procedures.
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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OSH REQUIREMENTS
GENERAL REQUIREMENTSGENERAL REQUIREMENTS• SITE INSPECTION
Every part of an excavation over 2 m deep where workers work shall be inspected.
A competent person shall conduct daily inspections of excavations, adjacent areas, and protective systems for evidence of a situation that could result to an accident.
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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EXCAVATION SAFETY
What’swrongwiththis
excavation situation?
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.
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THE END
By: Engr. Joji C. Valenciano, C.E., M.C.M., S.C.