Document ID: chunk:federal_register_of_legislation:F2016L00416:reg:4:p16
Version: federal_register_of_legislation:F2016L00416
Segment Type: reg
Provision Reference: reg 4 (pt 16/21)
Character Range: 72094–74879

ground support system must be designed to resist the expected ground pressures and potential for collapse.

Hydraulic support systems may become unreliable if not properly maintained and properly used. Frequent inspections of pressure hoses and rams are necessary to detect abrasion, fatigue or damage such as bent or notched rams.

When a trench has been fully supported the hydraulic support systems should be dismantled
to prevent costly damage. The hydraulic supports should be inspected, repaired if necessary
and carefully stored prior to re-use.

Further information on hydraulic shoring is available in AS 5047: Hydraulic shoring and trench lining equipment.

Figure 12 Hydraulic shoring (soldier set style)

Steel sheet piling
Steel sheet piling is generally used on major excavations such as large building foundations
or where large embankments are to be held back and can be installed prior to excavation work commencing. It is also used where an excavation is in close proximity to adjoining buildings
(see Figure 13).
Sheet piling may be used when the ground is so unstable that side wall collapse is likely to occur during excavation, for example in loose and running sand. In such cases, sheet piling should be installed before excavation commences.

Figure 13 Steel sheet piling

Steel trench sheeting
Other methods of excavation may require the use of steel trench sheeting or shoring.
It is positioned and pneumatically driven in to final depth. Toms and walings are placed
into position as the soil is excavated. Although timber can be used it is more efficient to
use adjustable jacks or struts (see Figure 14).
Steel trench sheeting is lighter weight than normal sheet piling and in some circumstances
may be driven by hand-held pneumatic hammers or electrical operated vibrating hammers.
The potential for manual handling injuries to occur in this operation is very high, as is the risk
of lacerations due to sharp metal protrusions. These risks should be addressed prior to commencement of driving the steel sheet. Any projections on the underside of the anvil
of jack hammers should be removed to prevent damage to the driving cap and potential injury
to the operator.

During driving operations, if it is likely that workers may be exposed to noise levels in excess
of the exposure standard, a method of controlling the noise exposure is required.

Steel shoring and trench lining equipment should be designed by a competent person. Further information on steel shoring can be found in AS 4744.1: Steel shoring and trench lining – Design.

Figure 14 Steel trench sheeting and jacks

Timber soldier sets
The soldier set is a simple form of trench support set which can be formed with steel or timber. This system is mostly used in rock, stiff clays and