A deep earth cutting is always required when roads, railway lines and under-earth projects are built as per the level of the soil surface. This is necessary to keep soil from falling at the soil-cut parts. Here, there are basically two requirements – to complete the basement works in the first phase of construction and during when construction takes place above or below the soil-cut areas. Some safety norms are to be followed in order to prevent the soil from eroding.
For a building constructed upon a hill or dam, it is necessary to save the surface area. These structures are called earth-retaining structures. The most common earth-retaining structures are walls built of stone or cement concrete, cantilevers made of steel bars and concrete, counter forts retaining walls, sheet piles using steel plates etc. The main problem to be addressed at the time of these constructions is that these walls should support the inner pressure of the cutting face. And if it is a public construction, a speedy finishing of the work is needed as well.
At this time, soil nailing, an earth stabilizing technique by digging soil can be used. Iron bars are fixed into the soil depth in order to prevent it from falling off. Along with this, there is a fitting of vertical bars also to keep it strong. Connecting these iron bars by steel wire mesh and filling it with concrete skin will ensure that the cutting face of the soil remains strong.
Considering the sheer strength of the soil, a study on the soil including its pressure and depth using computer software can be done before soil nailing. Normally, 25 mm to 50 mm solid bars, pipes and nails are used for this. The important point to be taken into account is that soil nailing is not suitable for all kinds of soil. For eg, it does not work well with wet soil or loose soil.