ever see a human safety grave

8/8/2019 Ever See a Human Safety Grave

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Ever see a Human Safety Grave

Well if you don't follow the training

during excavation sites you will see itup close and personal

P bar Y Safety Consultants Alberta Canada


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To provide staff with an appreciation of the hazards associated with groundworks onconstruction sites and best practice of groundwork systems.

Aim ofTalk



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Design & Planning

Following items must be taken into account;

Nature of soil.

Size & depth of excavation. Method of excavation.

Proximity of other structures, services, or sources of

vibration.

Duration of work.

Well point dewatering systems.

Weather & moisture conditions.

Land contamination.P bar Y Safety Consultants Alberta Canada


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Excavation Support

After taking into account design & planning the appropriate method of

support can be made;

Battering back sides of excavation to suitable angle.

Timber framing.

Trench box.

Drag box.

Slide Rail System.

Vertical Shore. Waler Frames.

Light Duty Bracing.

Heavy Duty Bracing.

Hydraulic / Mechanical Struts.P bar Y Safety Consultants Alberta Canada


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In very stable ground,

poling boards and struts

may be sufficient.

Moderately firm groundmay require open

boarding with walings

only.

Timber Framing



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Timber Framing

In loose ground the

whole face of the

excavation may need

close boarding.

Further walings and

struts are installed as the

depth increases.



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Timber Framing



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Trench and manhole boxes are generally

the first choice for the rapid shoring of

trench runs in non urban

Trench Box System



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Trench Box System

Used in multiples to

continuously support a length of

trench.

Variety of sizes, usually base box

(typically 2.5m) and up to 2 top

extension boxes.

Generally a 360 excavator is

required particularly as large

pulling forces are required to

extract boxes in cohesive soils.P bar Y Safety Consultants Alberta Canada


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Trench Box System

Used for linear shoring generally

up to 4m wide x 6m deep in

reasonable ground conditions.

Not recommended inwaterlogged ground.



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Larger 4m high boxes can weigh over 4 tonnes.

Trench Box System



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Drag Box System

Used for short-term protection

of the workforce in non-urban

environments typically for

pipeline installation.

Generally a single unit to

support trenches up to 4m wide

x 4m deep in good stable ground

conditions.

Available up to 7.5m long and

can weigh in excess of 6 tonnes.



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Drag Box System

Designed to be pulled or

dragged through the trench by

the excavator as work proceeds.

Intended to provide a secure

working area for operatives

rather than an effective means

of preventing ground

movement.

Operatives should ensure they

enter the area within the area

protected ie. Not from rear or

front.



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Slide Rail Systems

A specialist linear shoring system

where positive ground support

is required.

Comprises posts, sliding panels

& struts.

Forms a continuous line of

support, typically up to 7m wide

x 7m deep.

Advantages is much greater

depths & widths with greater

strut clearance for pipe

installation.



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Vertical Shores

Vertical shores can be rapidly

installed to provide short term

intermittent support of

relatively shallow trenches in

good ground conditions.

A hydraulically operated

intermittent system comprising

of vertical aluminium rails

strutted apart by two hydraulicrams.

Used for narrow / shallow

trenches, typically 2m wide x 2m

deep.P bar Y Safety Consultants Alberta Canada


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Waler Frames

Waler frames and sheeting

provide a very versatile means

of supporting medium sized

trenches, giving very positive

ground support, particularly inurban environments.

Support trenches up to 4m wide

x 6m deep in all types of ground.

Need to drive trench sheets can

result in a longer installation

period.



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Very positive support to the surrounding ground is provided by the hydraulic

installation forces exerted by the pressurised Waler frames.

In poor conditions it is advisable to have the system designed by a qualified

engineer to determine the strength and spacing requirement.

Waler Frames



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Light Duty Bracing Frames

For smaller excavations where

support is required on all 4

sides, manhole braces and

trench sheeting provide the

safest, quickest and mosteconomical solution for positive

earth support.

Comprises of 4 hydraulically

operated individual telescopiclegs, either single or double

acting rams.

Light duty frames used in

excavations up to 6m square xP bar Y Safety Consultants Alberta Canada


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Light Duty Bracing Frames

In excavations greater than 3.5m deep, or poor ground conditions, it is

advisable to have the system designed by a qualified engineer.

A series of brace frames are used in conjunction with trench sheeting to

support the depth of the excavation.P bar Y Safety Consultants Alberta Canada


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Heavy Duty Bracing Frames

Heavy-duty bracing frames and

struts can be combined to

provide support for larger

excavations and cofferdams.

Available in lengths exceeding

20m. Each leg incorporates a

hydraulic double acting ram.

It is essential that a qualified

engineer designs the supporting

system.

Due to length and weight,

installation is usually carried out

leg by leg at reduced levels.P bar Y Safety Consultants Alberta Canada


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Hydraulic or Mechanical Struts

Hydraulic or mechanical struts are

generally used for high axial load

propping applications such as

cross strutting to supporting

frames or horizontal or rakingsupport to pile caps.

Available up to 250 tonnes load

capacity. Each strut assembly

incorporates hydraulicadjustment.



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Hydraulic or Mechanical Struts

Usually modular incorporating fixed length extension sections.

It is essential that a qualified engineer design these supporting systems.P bar Y Safety Consultants Alberta Canada


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Method Dependant on risks (as section 7.21 code of construction safety practise

Dubai)

Cross over points 600 mm wide with barrier protection

Lighting / warning signs

Access & Egress; People Protection



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Excavation may be classed as a

confined space

Regular atmospheric monitoring

is required so as to ensure the

atmosphere remains fit to

breathe.

Exhaust gases from excavators or

other combustion engines, and

other heavier gases (LPG) candescend into excavations. Vent

or mechanical ventilation to

prevent the atmosphere

becoming contaminated.

Ventilation



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Suitable and sufficient edge protection must be provided at working places with

exposed edges, holes or shafts where persons or material could fall.

Edge Protection



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Supervision & Inspections

All excavations must be inspected by a competent person:

At the start of any shift.

After any event likely to have affected the strength or stability of

the excavation.

After any accident fall of rock, earth or similar material.

Regardless of above, all excavations must be inspected at a

maximum interval of 7 days, and a written report produced within

24 hours of that inspection.P bar Y Safety Consultants Alberta Canada


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Excavators

Mechanical excavators pose several problems when working

adjacent to excavations.

Vibration can induce instability to the surrounding area.

Exhaust gases can descend into excavations.

Where they are used as cranes;

Check Valves should be fitted to hydraulics.

If no restriction fitted, ASL

Imust be fitted.

SWL must be marked on machine and not exceeded.

Designated lift eye must be used to attach any lifting

attachment.

Bucket must be removed from machine.P bar Y Safety Consultants Alberta Canada


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Always consider the hazards

and PLAN the work.

Use the company

procedures and local

guidance to help plan and

control your excavationwork.

Conclusion


ever see a human safety grave

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