The jet grouting method is the perfect solution for underpinning existing foundations. Underpinning is often necessary when new structures with a deeper foundation level are erected next to existing buildings. The difference in height can be securely bridged with jet grouted elements. The underpinning body is usually shaped like a triangle. The individual jet grout sections are constructed using the back-step method in order to avoid overloading the existing foundations and to minimise subsidence. When working with greater underpinning heights, additional retaining elements such as grouted anchors or micropiles can increase stability. Jet grouting can also be used to stabilise machine foundations that are sensitive to subsidence.
Lowering the groundwater level for producing deep construction pits in inner-city areas is problematic. In order to circumvent this problem, watertight construction pit enclosures consisting of diaphragm walls or sheet pile walls with sealing floor slabs are frequently the solution of choice. Jet grout columns of up to 5m in diameter can be realised in suitable soils. Combining these slabs with an anti-buoyancy protection system made of micropiles allows for the implementation of very economical design variants.
Rigorous quality control coupled with dynamic adjustment of the design is required for the successful implementation of deep jet grout slabs. Our in-house, highly qualified construction site teams have extensive experience in the implementation of these complex construction tasks. This helps us to ensure safe execution.
Tried and tested in tunnelling
Moving tunnel boring machines in and out of the approach and entry pits is always a challenge, especially when the tunnel is below groundwater level. Sealing blocks made from jet grout are a reliable and economical solution.
These sealing blocks can also be used for inserting and removing tunnel boring machines if the entry pit has not yet been constructed.
Improving the subsoil in soft soils and soils with low load-bearing capacity
In addition to their structural function, jet grout elements can also be used for soil improvement. A grid of jet grouted columns can be used to significantly improve the subsoil, especially in soft soils with low load-bearing capacity. A targeted subsoil survey must be carried out to locate the unsuitable soil areas. The next step is to define which measures are to be taken in order to achieve the desired soil properties.
Jet grouted piles
For aggressive substrate conditions
The jet grouting method is also used to construct micropiles. Jet grouted elements can improve the durability of the grout body, especially in aggressive subsoil conditions. After drilling, the pile borehole, the area where the force is to be applied, is widened using the jet grouting method and the load-bearing element is then incorporated into the newly constructed body.