We have already discussed many posts about problems and necessary solutions for foundation problems associated with black cotton soils and expansive soils as well. Many of these posts are about drainage control. In this post we will discuss another method of drainage control in black cotton soils.
Drainage control is the only cheapest way to rehabilitate an existing foundation. Depending on the various methods of drainage control the cost involvement are different. Here application of cut-off wall as drainage control will be discussed. The phrase ‘multiple solutions’ is used as it is also a means of underpinning for a foundation to be rehabilitated.
The cut-off wall is a barrier that prevents moisture to penetrate horizontally to a foundation system. These are a vertical walls to restrict movement of moisture from either side of it - both from foundation outer perimeter ground and outer to foundation sides. He who deals with expansive soil like black cotton soil, knows the importance of moisture barrier in controlling both swelling and shrinkage properties of soils. By preventing moisture gaining and releasing, a black cotton soil may behave as inert material.
Now we will learn about cut-off wall. Cut-off walls can be made of concrete which is attached or abuts to perimeter of existing foundation to be repaired. With the purpose of drainage control, they may provide a provision to transfer the loads that are arrived from structure through foundation to deeper stratum of soils. Thus they may be used as an option of underpinning which is required to perform a further rehabilitation purposes.