The term 'Mixed-In-Place' describes the process of mixing soil in-situ with binder. During this process, the existing pores within the soil structure are filled with the binder slurry. The result of this process is a strengthened body of soil the shape of which is defined by the geometry of the augers.
Construction of an MIP trench is carried out by drilling a triple continuous flight auger to the required depth. During drilling and withdrawal of the augers, the soil structure is destroyed, the soil is thoroughly mixed and binder slurry is introduced through the hollow stems of the augers.
In order to achieve complete homogenisation of the soil during mixing, the rig operator is able to vary the direction of rotation for each individualauger and at the same time raise or lower the sledge mounted augers.
When constructing Retaining Walls:
MIP cut-off wall with inserted sheet pile wall
MIP retaining wall with inserted H-beams at the exposed face; with – or without tie-tacks
MIP retaining wall with secant/contiguous piles
MIP retaining wall wire mesh reinforced, with soil nailing
Shaving of the exposed wall face
Optionally, the MIP body at the exposed wall face can be smoothened by a chisel or by milling.
Cut-off walls have no structural function. In conjunction with natural or artificial barriers, they provide watertight troughs (generally Kf ≤ 1 x 10-8 m/s). They are also used in connection with the restoration and remediation of river embankments and dykes.
MIP Process for In-situ Immobilisation
The MIP process can also be used for treating contaminated soil or landfill by introducing binder slurry to immobilise the contaminants.
Application of the process is in particular economically viable whenever extensive specialist foundation construction works would be required in order to carry out traditional excavation and removal of the contaminated materials. This is generally the case in inner-city areas.
Single MIP elements or MIP-wall sections can be used as foundation elements for permanent load transfer, or as permanent ground improvement.