What Are The Main Causes of Foundation Failure?

Few outcomes are more catastrophic for a structure than foundation failure. Depending on the reason, remediation measures can be highly expensive and, in extreme cases, the structure may have to be relocated. Below is an overview of the main causes of foundation failure and how they may be anticipated and/or avoided.

Masonry Settles Unequally

Mortar joints can shrink and compress, causing unequal settlement of the masonry. These measures are recommended to reduce this risk:

  • The masonry mortar should have the required stiffness
  • The masonry work should be watered properly
  • The masonry should be raised evenly- height will depend on whether lime or cement mortar is used

Uneven Settlement Of The Subsoil

This phenomenon occurs due to issues like unequal load distribution and inconsistent bearing power of the subsoil. When this happens, cracks appear in the foundation and can develop into major defects. The measures below can be adopted to prevent this type of failure:

  • Ensuring that foundations always rest on hard moorum or rock
  • Matching the foundation design to the subsoil type
  • Making sure that sustainable bearing pressure on the soil is not exceeded
  • Checking for any load and modifying the design accordingly

Moisture Withdraws From the Subsoil

This issue occurs in areas where water table heights vary considerably. As the water table drops, the soil particles lose their cohesion, resulting in soil shrinkage and building cracks. In order to prevent such failure, piles must be driven into the hard rock.

Superstructure Experiences Lateral Pressure

Lateral pressure can be created by strong wind action or the thrust of a pitched roof, causing a wall to overturn. To prevent this type of failure, design the structure with a sufficiently-wide base and take worst-case scenarios into account when designing the foundation.

Horizontal Earth Movement

Very soft soil can collapse under load action, especially on sloping ground, river banks, etc. In places like these, it may be necessary to build retaining walls or driving sheet pilings to prevent the soil from moving.

Tree and Shrub Transpiration

Tree roots planted near buildings can extend to the foundation level and absorb moisture. First a depression on the ground will appear, followed by cracks in foundation. To prevent this outcome, take the following steps:

  • Ensure that the foundation is sufficiently deep
  • Keep rapidly-growing trees at least 25 to 30 feet from the building

Environmental Challenges

Foundations may be damaged by heavy rains, a sudden temperature change, or frost. Rain water may form pockets along walls, and as it descends, it may carry certain chemicals and salts derived from sewage and other sources. These substances can react with the foundation materials and turn them into powder. The following remedial measures should be taken:

  • Add underground drains
  • After masonry work is complete, fill the trenches along the foundation wall with tightly-packed soil
  • Construct a subtle slope to keep rain water away from the wall

Advance Planning in Design Can Improve Project Integrity

Anticipating common causes of foundation failure can ensure that your project structure is built to last. The team at DDA Engineers, P.A. has the professional skills and experience to take the best approach for building longevity, so if you’re planning a project in or around Miami, call us at (305) 666-0711 today.

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