Tie rod systems are used in all cases in which two or more points of a structure must be stabilized relative to one another. Earth filled dams that are laterally stabilixed by driven sheet piles are stabilizing cross ties with remarkable tensile force capacity can also be transferred using tie rods.

Uplift occurs in a large variety of

foundation structures independent of

the existing water level or by

variable superimposed loads. The

bottom slab of construction

excavations (underwater concrete or

high-pressure injection slabs) must

be secured temporarily during the

period of construction. This also

applies to trough structures such as

descending tunnel entrances for

subway construction. Tensile piles

are increasingly used as an economic

alternative to mass concrete. If

position accuracy is particularly

important – for instance, during the

construction of dry docks –

tensioned anchors can be used. The

principle advantage of this system

construction method results from

shortened construction times due to

less excavation work and a reduction

of bottom slab thicknesses.

However, alternating loads can result

from pile uplift control such as

inspection work in settling basins.

In cases like these, loads can be

economically changed from

compression to tension without any

problems.

Tensile loads in soil can be

economically tied back using ground

anchors or tensile piles. Large, heavy

and noticeable counter balances or

retaining structures can be

eliminated because tensile loads are

directly transferred into the soil so

that only unobtrusive transition

structures and connections remain at

the surface.

Depending on the characteristics of

the load-bearing soil strata, and the

method of excavation, different

varieties of civil engineering systems

can be chosen. The characteristics of

the ground used for anchorage are

also irrelevant - whether rock, non-

cohesive soils such as sand or gravel,

cohesive soils such as clay or silt,

organic soils with and without

groundwater or even permafrost and

Antarctic ice - DYWIDAG Systems

have permanently proven their

aptitude in terms of function and

economy.

Structures that are at risk of tipping

such as masts, towers or wind

generators can be permanently

stabilized using micropiles. As a

fully grouted, passive system,

micropiles can accomodate tensile,

compression and alternating loads.

To minimize settlements,

deformations and movements,

actively tensioned ground anchors

can also be used to transfer tensile

forces. Anticipated compression

forces are absorbed via a stiff

shallow foundation or via additional

compression piles. Thus, a build-up

of forces and movements can be

minimized or prevented. The

structures can even be further

reinforced at a later stage if the

foundation shows early stages of

overload or if exterior impact is

more severe (wind, earthquakes,

snow, etc.).

Large and deep excavations are

becoming more and more important

especially in intra-urban areas, and

ground anchors have proven

themselves particularly useful in this

extremely challenging civil

engineering application. Very often,

they are the only way to support

excavations. Furthermore, anchors

are often the most economical

solution in comparison to steel or

concrete cross braces: Unrestricted

access to the excavation,

uninterrupted and obstruction-free

crane operation, no risk of buckling

and almost limitless options in terms

of anchor forces.

If required, ground anchors can be

removed from the soil after

completing civil engineering work in

order not to interfere with

subsequent site activities. Due to

their being an active system, ground

anchors are tensioned so that

deformations of the excavation

confinement are actively managed.

Controlled load application is

ensured before excavation is begun

so that construction work is safe for

all parties involved as well as for

adjacent buildings. In excavations

where deformations are irrelevant,

passive systems such as soil nails or

tension piles can be used.

The development and expansion of

infrastructure – and, more

specifically, the construction of high-

speed corridors – poses significant

requirements in terms of route

planning. The expansion of

motorways by adding more lanes

often requires comprehensive earth

work and results in high, steep

embankments in the cut slopes and

hills. The faces of slope stabilization

structures – e.g. shotcrete

construction or walls consisting of

prefabricated concrete segments –

are often anchored in the soil using

soil nails. Rock fall protection mesh

can also be fixed to the rock using

this technique. Soil nailing stabilizes

and consolidates the complete soil.

The entire soil wedge including the

slip circle is nailed and secured

against tilting, sliding, gliding, shear

failure and loss of position. Passive

Systems are usually used in this case

because deformations of the

supporting system are irrelevant in

most cases – the soil nails are only

loaded when movements in the slope

or at the face start. At full load, the

earth pressure is completely

absorbed and transferred by the solid

nails. If deformations are important

in slope stabilization projects, an

active system such as ground

anchors can be chosen.

Individual foundations, strip

foundations and foundation slabs are

increasingly stabilized by micropiles

that transfer loads safely and

sustainably into the load-bearing

soil. The fact that they can be

installed by very small space saving

drilling equipment is one of the

decisive reasons for using micropiles

in such structures. Micropile

foundations can be used herever

access is difficult; this includes

narrow basements, the space

underneath bridge decks or where

installation from pontoons is

necessary. The light weight and the

ensuing required ground level also

play a part. A posterior

reinforcement and strengthening of

foundations or load redistribution

can thus be carried out quickly and

easily. This is achieved by the

excellent relation between the

borehole diameter and the

transferred force. When used as skin

friction piles, micropiles with their

unmatched high steel ratio can

transfer forces in boreholes up to

300mm in diameter and in depths of

80m and more into the subsoil.

Additionally, GEWl® and GEWl®

Plus Piles can transfer tensile,

compressive and alternating loads.

Thus, construction stages or crane

undations can be anchored or

founded without any problems.

New criteria for assessment and

higher maximum water levels pose

higher requirements for retaining

walls and dams. Existing structures

must comply with completely new

requirements for stability caused by

higher freezing pressures, updated

earthquake load zones and new

requirements in terms of

impermeability and position stability

or stability against overturning.

For reinforcing and simultaneous

rehabilitation, this challenging

increase in load bearing capacity can

often be reached by a massive

anchoring of the dam structure. In

this case, boreholes are drilled

vertically from the dam crest, and

the dam wall is anchored at the

bottom using ground anchors. Lift-

off suction power can also be

overcome by anchoring overflow

structures and stilling basins

permanently into the soil using

anchors or tensile piles. Depending

on water levels, different load

conditions can also be safely

absorbed by anchors (in case of

tensile load only) or micropiles

(even for alternating loads) at

retaining dams. Caissons consisting

of driven sheet piles are built for

cofferdams or new quays. They are

assembled at the head using tie rod

systems and thus stabilized against

uplift during sand filling and against

subsequent loads resulting from dead

weight and traffic.