Our geotechnical systems stabilize the ground and support infrastructure worldwide
DYWIDAG is a specialist manufacturer and supplier of geotechnical systems with over 50 years of experience—and sector expertise.
Strength and stability
DYWIDAG geotechnical systems provide slope stabilization, support of retained structures, enable deep excavations and piled foundations.
Stressing and testing services
DYWIDAG is able to provide a range of stressing and testing services for ground anchors, soil nails and tension piles as well as a large equipment fleet which is available for hire on specialist projects.
Options for monitoring systems
Our engineers can configure smart geotechnical systems—providing asset data and infrastructure intelligence to inform timely and crucial decision-making. We have the experience to interpret the scope of your project and ensure we meet your requirements with an appropriate and cost-effective response.
With production facilities in strategic locations worldwide, and mobile production lines for major projects, we have the global coverage to service local demands.
Fields of Application
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.
Slope Stabilization and Sidehill Cuts
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.
Foundations and Underpinning
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 wherever 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 foundations can be anchored or founded without any problems.
Hydraulic, Power Plant and Embankment Construction
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.
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
Tie Rods and Braces
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 stabilized by driven sheet piles are stabilized by tiebacks at the head. Stabilizing cross ties with remarkable tensile force capacity can also be realized. Drifting horizontal forces in individual or strip foundations can also be transferred using tie rods.
Anchoring of Tensile Loads
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.
Stability against Overturning
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.).