SOIL MECHANICS

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SOIL MECHANICS

Before a determination if foundation repair is necessary, it is important to have a basic understanding of the geological content of the existing soils.

Soil composition can radically vary from one lot to another for a number of reasons. If foundation repair is necessary, the solution could be a different pier system, drainage solution, or something else.

Often times simple corrections to grading, water mitigation, a redirected A/C drip line, or even a repaired plumbing leak can prevent potential foundation repairs in the future.

Having a basic understanding of both physics and applied mechanics is of paramount importance when assessing potential foundation repair. A direct correlation between the foundation movement, and the cause movement in the soil must be identified to determine the correct foundation repair.

Depending on the plasticity index of the clay soils, the amount of shrinking or swelling will vary.

For these reasons, this information is essential in identifying the right solution for long term stability.

Plasticity index is known as Atterberg limits, and is the basic measure of the critical water contents of soil.

“Because water serves as the catalyst to the expansion of the clay or silty soil, if an equilibrium does not exist around a foundation that has a PI above 24, structural failure is highly probable.”

Soil injection, drainage, and a complete underpinning of a foundation lifted beyond the total potential vertical rise, can be used to mitigate further movement. This is often misinterpreted as settlement, or soil consolidation, where no problem exists at all.

Consolidation is a process by which soils decrease in volume. It occurs when stress is applied to a soil that causes the soil particles to pack together more tightly, therefore reducing volume. Once saturated soil that had the water squeezed out, can create a need for foundation repair.

“When stress is removed from a consolidated soil, the soil will rebound, drawing water back into the pores and regaining some of the volume it had lost in the consolidation process. ”