Overview Diaphragm Wall Techniques

Diaphragm walls have evolved as a standard technique in specialist foundation engineering, by which a continuous wall is constructed from a series of rectangular overlapping panels. During the excavation, the open trench is stabilized and supported by a thixotropic slurry. Individual panels are excavated by duty-cycle cranes using a diaphragm wall grab or trench cutter. Due to the different construction techniques available, diaphragm walls can now be constructed in all kinds of soils, even in very hard soil formations and also in rock.

Key advantages of the technique:

  • Application in difficult and hard soil conditions as well as rock
  • Vibration-free technique
  • Extensive depths are possible (>100m)

The main areas of application are retaining and cut-off walls as well as vertical foundation elements.

Cutter Diaphragm Wall

Since its introduction in 1984, the cutter diaphragm walling technique using the BAUER Cutter (BC) has developed rapidly. As a result of the wealth of experience accumulated over the following decades, the challenge being faced today is cutting trenches into extremely hard rock and achieving ever-increasing depths. Through project-specific adaptations of the cutter wheels, high excavation outputs can frequently be achieved. The open trench which is stabilized and supported by a thixotropic slurry is excavated in a continuous operation.

The slurry charged with spoil material is conveyed to the surface by a mud pump, which is mounted inside the cutter frame. The charged slurry then passes through a desanding plant. Here, the solid particles are separated out from the support slurry. The cleaned slurry is then pumped back into the slurry circulation system for reuse as support slurry in the trench. With the cutter technique depths of more than 100 m can be achieved.

Grabbed Diaphragm Wall

Drilling with Cased Continuous Flight Auger is one of the single-pass drilling techniques. During the drilling process, a continuous flight auger protected by a counter-rotating casing string conveys the drill spoil to the surface. Concrete is subsequently poured through the hollow stem of the auger. With drilling diameters of up to 600 mm, FOW counts as one of the CCFA drilling techniques.