Use of plastic sheets for slope protection in a shallow excavation

E A R T H W O R K S U P P O R T S

TIMBER PLANKING

TIMBER SOLDIERS

E A R T H W O R K S U P P O R T S

STEEL SOLDIER PILES

TIMBER PLANKING

E A R T H W O R K S U P P O R T S

Excavation supports using soldier beam and lagging.

Two examples of soldier beams and lagging method used for retaining walls

Two examples of soldier beams and lagging method used for retaining walls

Examples of soldier beams and lagging method used for retaining walls

E A R T H W O R K S U P P O R T S

STEEL SHEET PILES

E A R T H W O R K S U P P O R T S

STEEL SHEET PILES

Bracing for shallow trenches (a) intermittent sheeting and bracing

Bracing for shallow trenches. (b) continuous sheeting and bracing,

Bracing for shallow trenches. (c) trench shielding

A typical trench box

Soil Nailing Examples

Soil Nailing Examples

Soil Nailing Examples

Schematic diagram of narrow excavation bracing

Internal struts

Support for Rakers

Raker bracing for wide excavations

Excavationsub-grade

Ground surface

Grout or transfer materials

Stressing unit

Sheeting

Tendon

10-200

Bond freezone

Assumed surface of sliding wedge

Tieback installed at 10 to 20° down from horizontal

Tied-back concrete wall constructed underground for excavation support

Tieback being installed

Tieback Examples

Ground freezing is a technique that has been used extensively for groundwater control and excavation support in the underground construction industry for over 100 years.

The process involves the circulation of a refrigerated coolant through a series of subsurface pipes to convert soil water to ice, creating a strong watertight material.

The material is so strong, in fact, that it is routinely used as the only method of groundwater control and soil support for the construction of shafts hundreds of feet into water-bearing soils.

Most ground freezing systems are quite similar in principal.

The single most important co mponent of a ground freezing system is the subsurface refrigeration system, consisting of a series of refrigeration pipes installed with various drilling techniques.

Depending upon the application, the coolant can be brought to temperatures well below -150 degrees celcius

Ground freezing can be achieved by using either a large portable

refrigeration plant or liquid nitrogen.

After the initial freezing has been completed and the frozen barrier is in

place, the required refrigeration capacity is significantly reduced to

maintain the frozen barrier.